Professor Roderick King

Trained as a biochemist at Bath and obtaining a doctorate in medical biochemistry at Leeds, Rod has spent over 35 years in academic life both as a lecturer and a researcher. His first research post (MRC) was with Professor Monty Lowsowsky at Jimmy's studying lipid metabolism but soon moved across the city to work with Professor John Golligher at Surgery LGI Leeds. Working with a dynamic team engaged upon surgical research proved to be too irresistible to contemplate thought of movement elsewhere or other discipline. He has extensive experience of research with human subjects as patients and also subjects in normal health in a variety of clinical contexts. Rod progressed from senior biochemist in Surgery at Leeds LGI to principal research fellow at Leeds Medical School. During this period he gained considerable ability and expertise in the design, implementation and analysis of data gained from many research investigations in the clinical area. Rod specialised on wet chemistry techniques and led the laboratory team within the academic unit at the LGI. He was fortunate to work on quantitative research with Professor Morgan in Chemical Pathology, with Dr Burkinshaw in the MRC neutron activation facility at Leeds and with Professors Johnston, Hill and McMahon in Surgical Research. A consequence of such activity is the variety of networks developed, not only academically but also with commercial organisations. Whilst working within clinical nutrition an idea was developed into a company through the help of ULIS (Innovations, Leeds University) and also LeedsMet. To achieve this necessitated comprehensive technical, industrial and commercial involvement between and with patent agents, suppliers, plant manufacturers, ingredient producers, marketing agents, product consultants, retail organisations and others on a national and international scale. He also worked with the Open University both as a tutor and consultant gaining experience with distance learning techniques and the teaching of science. Rod joined the School of Leisure and Sports Studies in 2000. He moved to the School from Leeds University where he had already worked in close collaboration with colleagues in this School. He was appointed as a Reader in 2004 and Professor in September 2004. This lecture was recorded on 9 March 2006.

Background: Our aim was to evolve a simpler, more physiological type of gastroplasty that would dispense with implanted foreign material such as bands and reservoirs. The Magenstrasse, or "street of the stomach", is a long narrow tube fashioned from the lesser curvature, which conveys food from the esophagus to the antral Mill. Normal antral grinding of solid food and antro-pyloro-duodenal regulation of gastric emptying and secretion are preserved. Methods: 100 patients with morbid obesity (83M, 17F, mean age 40 years) were treated by the Magenstrasse and Mill procedure and followed-up for 1-5 years. Mean preoperative BMI was 46.3 kg/m

2

Plasminogen activator inhibitor 1 (PAI-1), tissue plasminogen activator (t-PA), fibrinogen and insulin were measured in 43 patients 3 years after they had undergone the Magenstrasse and Mill (MM) procedure and in 43 morbidly obese (MO) patients. Mean plasma PAI-1 was 61 ng/ml in the MO group compared to 30 ng/ml in the MM group (p < 0.0001); mean plasma t-PA was 10 ng/ml in the MO group compared to 7 ng/ml in the MM group (p < 0.001). Mean fibrinogen was 3.6 g/l in the MO group compared to 3.2 g/l in the MM group (p < 0.05). Mean plasma insulin levels were 32 U/ml in the MO group compared to 15 U/ml in the MM group. These changes suggest that use of the MM procedure may reduce mortality and morbidity from coronary heart disease in these high-risk obese patients.

Summary

Background  We evaluated the effect of the Magenstrasse and Mill (M & M) operation–a new form of non‐banded vertical gastroplasty–on weight loss, plasma leptin levels and insulin resistance.

Methods  Fasting plasma glucose, leptin and insulin levels were measured in 12 normal controls, 39 morbidly obese patients and 39 patients a median 3 years after the M & M procedure. Insulin resistance was calculated by the homeostasis model insulin resistance index.

Results  Body mass index mean (s.d.) decreased significantly (p < 0.0001), from 48(7) to 33(5) kg/m 2 , after the M & M procedure. Fasting plasma leptin concentration in the morbidly obese group was 37.9(15.4) ng/ml, significantly (p < 0.0001) higher than the control group (12.2(8.4)) and the M & M group (19.1(12.7)) ng/ml. Fasting plasma insulin concentrations were also significantly (p < 0.0001) higher in the morbidly obese group compared with than in the M & M group or in the control group: 35.5(22.3) mU/l, 15.5(7.1) mU/l and 13.6(3.4) mU/l, respectively. Insulin resistance was 9.6(7.2) in the morbidly obese group and 3.5(1.9) in the M & M group (p < 0.0001).

Conclusion  This is one of the first studies to show that the decrease in insulin resistance after weight loss achieved by anti‐obesity surgery is associated with significantly lower levels of plasma leptin.

PURPOSE: To investigate the effects of daily oral L-leucine ingestion on strength, bone mineral-free lean tissue mass (LTM) and fat mass (FM) of free living humans during a 12-wk resistance-training program. METHODS: Twenty-six initially untrained men (n = 13 per group) ingested either 4 g/d of L-leucine (leucine group: age 28.5 ± 8.2 y, body mass index 24.9 ± 4.2 kg/m2) or a corresponding amount of lactose (placebo group: age 28.2 ± 7.3 y, body mass index 24.9 ± 4.2 kg/m2). All participants trained under supervision twice per week following a prescribed resistance training program using eight standard exercise machines. Testing took place at baseline and at the end of the supplementation period. Strength on each exercise was assessed by five repetition maximum (5-RM), and body composition was assessed by dual energy X-ray absorptiometry (DXA). RESULTS: The leucine group demonstrated significantly higher gains in total 5-RM strength (sum of 5-RM in eight exercises) and 5-RM strength in five out of the eight exercises (P < .05). The percentage total 5-RM strength gains were 40.8% (± 7.8) and 31.0% (± 4.6) for the leucine and placebo groups respectively. Significant differences did not exist between groups in either total percentage LTM gains or total percentage FM losses (LTM: 2.9% ± 2.5 vs 2.0% ± 2.1, FM: 1.6% ± 15.6 vs 1.1% ± 7.6). CONCLUSION: These results suggest that 4 g/d of L-leucine supplementation may be used as a nutritional supplement to enhance strength performance during a 12-week resistance training program of initially untrained male participants.

The present study evaluated whether the inclusion of protein (PRO) and amino acids (AA) within a maltodextrin (MD) and galactose (GAL) recovery drink enhanced post-exercise liver and muscle glycogen repletion. A total of seven trained male cyclists completed two trials, separated by 7 d. Each trial involved 2 h of standardised intermittent cycling, followed by 4 h recovery. During recovery, one of two isoenergetic formulations, MD-GAL (0.9 g MD/kg body mass (BM) per h and 0.3 g GAL/kg BM per h) or MD-GAL-PRO+AA (0.5 g MD/kg BM per h, 0.3 g GAL/kg BM per h, 0.4 g whey PRO hydrolysate plus l-leucine and l-phenylalanine/kg BM per h) was ingested at every 30 min. Liver and muscle glycogen were measured after depletion exercise and at the end of recovery using 1H-13C-magnetic resonance spectroscopy. Despite higher postprandial insulin concentations for MD-GAL-PRO+AA compared with MD-GAL (61.3 (se 6.2) v. 29.6 (se 3.0) mU/l, (425.8 (se 43.1) v. 205.6 (se 20.8) pmol/l) P= 0.03), there were no significant differences in post-recovery liver (195.3 (se 2.6) v. 213.8 (se 18.0) mmol/l) or muscle glycogen concentrations (49.7 (se 4.0) v. 51.1 (se 7.9) mmol/l). The rate of muscle glycogen repletion was significantly higher for MD-GAL compared with MD-GAL-PRO+AA (5.8 (se 0.7) v. 3.7 (se 0.6) mmol/l per h, P= 0.04), while there were no significant differences in the rate of liver glycogen repletion (15.0 (se 2.5) v. 13.0 (se 2.7) mmol/l per h). PRO and AA within a MD-GAL recovery drink, compared with an isoenergetic mix of MD-GAL, did not enhance but matched liver and muscle glycogen recovery. This suggests that the increased postprandial insulinaemia only compensated for the lower MD content in the MD-GAL-PRO+AA treatment.

PURPOSE: This study determined the effect of ingesting galactose and glucose 30 min before exercise on exogenous and endogenous fuel use during exercise. METHODS: Nine trained male cyclists completed three bouts of cycling at 60% W(max) for 120 min after an overnight fast. Thirty minutes before exercise, the cyclists ingested a fluid formulation containing placebo, 75 g of galactose (Gal), or 75 g of glucose (Glu) to which (13)C tracers had been added, in a double-blind randomized manner. Indirect calorimetry and isotope ratio mass spectrometry were used to calculate fat oxidation, total carbohydrate (CHO) oxidation, exogenous CHO oxidation, plasma glucose oxidation, and endogenous liver and muscle CHO oxidation rates. RESULTS: Peak exogenous CHO oxidation was significantly higher after Glu (0.68 ± 0.08 g.min(-1), P < 0.05) compared with Gal (0.44 ± 0.02 g.min(-1)); however, mean rates were not significantly different (0.40 ± 0.03 vs. 0.36 ± 0.02 g.min(-1), respectively). Glu produced significantly higher exogenous CHO oxidation rates during the initial hour of exercise (P < 0.01), whereas glucose rates derived from Gal were significantly higher during the last hour (P < 0.01). Plasma glucose and liver glucose oxidation at 60 min of exercise were significantly higher for Glu (1.07 ± 0.1 g.min(-1), P < 0.05, and 0.57 ± 0.08 g.min(-1), P < 0.01) compared with Gal (0.64 ± 0.05 and 0.29 ± 0.03 g.min(-1), respectively). There were no significant differences in total CHO, whole body endogenous CHO, muscle glycogen, or fat oxidation between conditions. CONCLUSION: The preexercise consumption of Glu provides a higher exogenous source of CHO during the initial stages of exercise, but Gal provides the predominant exogenous source of fuel during the latter stages of exercise and reduces the reliance on liver glucose.

The utilisation of carbohydrate sources under exercise conditions is of considerable importance in performance sports. Incorporation of optimal profiles of macronutrients can improve endurance performance in athletes. However, gaining an understanding of the metabolic partitioning under sustained exercise can be problematical and isotope labelling approaches can help quantify substrate utilisation. The utilisation of oral galactose was investigated using (13)C-galactose and measurement of plasma galactose and glucose enrichment by liquid chromatography/isotope ratio mass spectrometry (LC/IRMS). As little as 100 μL plasma could readily be analysed with only minimal sample processing. Fucose was used as a chemical and isotopic internal standard for the quantitation of plasma galactose and glucose concentrations, and isotopic enrichment. The close elution of galactose and glucose required a correction routine to be implemented to allow the measurement, and correction, of plasma glucose δ(13)C, even in the presence of very highly enriched galactose. A Bland-Altman plot of glucose concentration measured by LC/IRMS against glucose measured by an enzymatic method showed good agreement between the methods. Data from seven trained cyclists, undergoing galactose supplementation before exercise, demonstrate that galactose is converted into glucose and is available for subsequent energy metabolism.

OBJECTIVE: The aim of this study was to investigate changes in cardiometabolic clustering characteristics in response to highly significant weight loss. BACKGROUND: Pre-post analysis of a lifestyle intervention for the treatment of obesity and the assessment of interrelated metabolic changes were analyzed using principal component analysis (PCA). A total of n=75 clinically obese boys and girls [standardized body mass index (sBMI) 3.07±0.59] aged 8-18 years were assessed after lifestyle intervention (30±12 days). RESULTS: There were favorable improvements in BMI waist circumference, fasting insulin, triglycerides (TGs), systolic blood pressure (SBP) and diastolic blood pressure (DBP) (all P<0.001). PCA was performed using a simple conceptual model of changes in six metabolic variables: Overall and central obesity (BMI and waist circumference), dyslipidemia [TG and high-density lipoprotein cholesterol (HDL-C)], insulin resistance [fasting insulin or homeostasis model assessment of insulin resistance (HOMA-IR)], and blood pressure [SBP or mean arterial pressure (MAP)]. PCA models consistently identified two factors underlying the changes in six cardiometabolic variables. These were labeled a "metabolic" factor, typically including waist circumference, fasting triglyceride, insulin, or HOMA-IR and HDL-C (negatively) and an "obesity/blood pressure" factor, typically loading waist, BMI, SBP or MAP, and occasionally fasting insulin/HOMA-IR). The metabolic and obesity/blood pressure factors explained 26.5%-28.4% and 30.4%-31.9%, of the variance in metabolic risk factors changes, respectively. Reductions in BMI, waist circumference, and HOMA-IR (or fasting insulin) were central underlying features of cardiometabolic changes. CONCLUSION: There were significant and favorable cardiometabolic risk factor changes to short-term weight-loss. A distinct clustering of cardiometabolic responses supports the etiological importance of both overall and central obesity and insulin resistance in the modification of cardiometabolic risk in obese youths.

This study assessed the effect of incorrect calculation of power output measurement on the ergogenic properties of creatine. Fifteen males performed repeated Wingate anaerobic tests, under baseline, placebo, and creatine conditions. Statistics showed significant differences (p < 0.05) following creatine-supplemented conditions compared with placebo conditions, whereas no significant differences existed between the baseline and placebo conditions. However, the performance enhancement effect of creatine became significant only when the corrected (for the inertia of the flywheel) method was employed for measuring peak and minimum power. Mean (�SD) values across all cycle sprints for placebo versus creatine were 1033 100 W versus 1130 95 W for peak power and 385 78 W versus 427 70 W for minimum power. No significant differences were shown using the uncorrected method for peak power (756 97 W versus 786 88�W) and minimum power 440 64 W pre versus 452 65 W post). In conclusion, the present study suggests that the potentiating effect of creatine might be underestimated if the inertial effects of the flywheel are not considered in power output determination.

The purpose of the study was to examine the effect of creatine (Cr) supplementation on anaerobic performance when ingesting creatine and carbohydrates (CHO) together. Twenty male physical education students comprised the two experimental (CR and CRCHO) and one control (CON) groups of the study. All groups performed three 30 s anaerobic Wingate tests (AWTs) interspersed with 6 minutes of recovery. The CR group (n = 7) ingested 5 g of Cr 5 times per day for 4 days. Subjects in the CRCHO group (n = 6) ingested the same quantity but additionally after each 5 g dose of Cr consumed 500 ml of a commercially available energy drink containing 100 g of simple sugars. Over all three AWTs average mean power improved significantly compared to baseline for the CR group (5.51%) but not for the CRCHO group (3.06%). Mean power for the second AWT was improved following the acute loading for the CR group only (4.54%) and for the third AWT for both CR (8.49%) and CRCHO (5.75%) groups. Over all three AWTs a significant change was recorded in average peak power following the acute loading for the CR group (8.26%) but not for the CRCHO group (4.11%). Peak power was significantly improved following the loading only for the CR group during the third AWT (19.79%). No changes in AWT performance were recorded for the CON group after intervention. The findings of the present study suggest that ingesting creatine together with carbohydrates will not further improve performance compared to the ingestion of creatine only.

BACKGROUND: The metabolic triad [fasting insulin, apolipoprotein B, and low-density lipoporotein (LDL) peak particle density] is characteristic of increased intra-abdominal adipose tissue and insulin resistance and can be predicted by the simple and adoptable screening tool, the hypertriglyceridemic waist. The associations between hypertriglyceridemic waist components [fasting triglycerides (TG) and waist circumference cut-points derived from a child-specific metabolic syndrome definition] with the metabolic triad were examined in obese youth before and after weight loss. METHODS: A continuous metabolic triad score (MTS) was calculated as a cumulative and standardized residual score of fasting insulin, apolipoprotein B, and LDL peak particle density (z-scores of the metabolic triad variables regressed onto age and sex). The predictive ability of TG and waist in assessing metabolic triad change was undertaken in 75 clinically obese boys and girls, aged 8-18, body mass index (BMI) 34.2±6.4 kg/m(2) before and after weight loss. RESULTS: Fasting TG concentrations (r(2)=0.216, P<0.0001) and waist circumference (r(2)=0.049, P=0.019) were both significant independent predictors of the cumulative MTS, together accounting for 26.5% of its total variance. All cardiometabolic risk factors [except a reduction in high-density lipoprotein cholesterol (HDL-C)] were favorably modified following weight loss. Fasting TG change was the only significant predictor of the MTS change (r(2)=0.177, P<0.0001). Waist circumference was not a significant predictor of MTS change. CONCLUSION: The reduction in fasting TG concentration (but not waist circumference) was the only significant predictor of MTS change. Fasting TG may be the most important metabolic syndrome component to best characterize the metabolic heterogeneity in obese cohorts and the changes in metabolic risk in clinically obese youth.

OBJECTIVE: Small, dense low-density lipoprotein (LDL) particles are highly atherogenic and strongly associated with obesity-related dyslipidemia. The metabolic inter-relationships between weight loss induced changes in waist circumference, triglycerides, insulin sensitivity and small-dense LDL particles in clinically obese children and adolescents have not been studied. METHODS: Seventy-five clinically obese boys and girls (standardized body mass index 3.07 ± 0.59, aged 8-18 years) were recruited. Anthropometric, body composition and cardiometabolic risk factors were measured pre- and post-weight loss. RESULTS: There were highly significant reductions in anthropometric, body composition and cardiometabolic risk factors. Triglyceride change was positively correlated with LDL peak particle density and percentage LDL pattern B changes (relative abundance of small, dense LDL particles). Multiple regression analyses showed that changes in triglyceride concentration accounted for between 24 and 18% of the variance in LDL peak particle density and percentage LDL pattern B change, respectively. Changes in waist circumference and insulin sensitivity did not predict these changes in LDL characteristics. CONCLUSION: Acute and highly significant weight loss significantly decreased LDL peak particle density and percentage LDL pattern B. The change in triglycerides was a strong predictor of LDL peak particle density and percentage LDL pattern B change.

Carbohydrate (CHO) ingestion during prolonged exercise is common practice amongst athletes and improves endurance performance. Glycogen is a limited energy resource during prolonged exercise and as such sparing glycogen has been proposed as a mechanism behind the ergogenic effect of CHO. However, evidence to support such an effect is equivocal and it appears that the dose of CHO may play an important role in this regard. The aim of this thesis was to investigate a dose response to prolonged exercise CHO ingestion on exogenous CHO, liver and muscle glycogen utilisation and exercise performance.  Two multiple condition studies were conducted consisting of either a 2 or 3 hour continuous period of fixed workload cycling followed by a 30 minute time trial. During the fixed workload period, a placebo solution or various CHO solutions were ingested which had been artificially labelled with a 13Carbon (13C) stable mass isotope tracer. By analysing the appearance of the 13C tracer in expired air and plasma glucose, rates of exogenous CHO, plasma glucose and liver and muscle glycogen were calculated. Study 1 investigated 4 CHO doses (60 to 112.5 g.h-1) using both single and multiple transportable CHO designed to saturate and over saturate the intestinal transport proteins SGLT1 and GLUT5 during 2 hours of continuous cycling at 77% V̇ O2max. Study 2 examined a smaller dose range (80 to 100 g.h-1) in order to provide evidence to the effectiveness of a 90 g.h-1 dose during 3 hours of continuous cycling at 60% VO2max. ̇  In Study 1 the ingestion of multiple transportable CHO at 90 g.h-1 improved performance by 9-15% and spared muscle glycogen relative to the ingestion of glucose only. Fat oxidation was spared relative to placebo ingestion with CHO. It was also seen that increasing CHO dose with ingestion of both single CHO and multiple transportable CHO at rates exceeding intestinal saturation did not further increase exogenous CHO oxidation, and had potentially negative consequences on time trial performance and endogenous substrate (fat and glycogen) oxidation. Study 2 showed that multiple transportable CHO ingestion at 90 g.h-1 produced a small reduction (17.8%) in muscle glycogen oxidation rate and an improvement (3.6 - 7.1%) in mean power output in the time trial, relative to 80 and 100 g.h-1 .  This thesis provides novel evidence that with the right dose of CHO ingestion during prolonged exercise, muscle glycogen was spared, which coincided with improved subsequent time trial performance. Further, the effect of ‘over-dosing’ exogenous CHO intake was potentially detrimental to endogenous substrate oxidation and time trial performance.

BACKGROUND: Increasing body mass index, cholesterol and body fat are associated with a better prognosis in patients with left ventricular systolic dysfunction (LVSD). Beta-blocker usage is associated with changes in body composition and increased body fat. The present study investigated 12-month changes in body composition in patients with LVSD initiated on beta-blocker therapy. METHODS: The relation between beta-blocker use and body composition was evaluated in 91 patients (75% male) with LVSD. Body composition was assessed by bioelectrical impedance. RESULTS: Seventeen patients died during the study period. There was no statistical difference among beta-blocker usage, beta-blocker type, or changes in body fat, basal metabolic rate, impedance, fat-free mass, fat mass and total body water. There were no significant differences between any of these measures and beta-blocker usage. CONCLUSION: After 12 months, changes in body composition were not found to be influenced by initiation of beta-blocker therapy in patients with LVSD.

The aim of the study was to compare the effects of high and low concentration carbohydrate (CHO) solutions on the endurance performance of recreational, male soccer players consumed prior to and during intense, intermittent exercise. Methods: Seven participants consumed four different fluids using a randomised double blind procedure, an 8% carbohydrate electrolyte solution (2.5% galactose and 5.5% glucose polymer) (8% CES), a 2.5% carbohydrate (2.5% galactose) electrolyte solution (2.5% CES), an electrolyte solution (E) and water (W). A further three participants acted as controls by consuming E only on four occasions. We used the Loughborough Intermittent Shuttle Test (LIST) to simulate the intense, intermittent nature of a soccer match. The LIST protocol consists of two parts: Part A required walking, jogging and sprinting, utilising a 20 m shuttle procedure, for 75 min, recovering for 3 min every 15 min. Part B required participants to perform intermittent running to exhaustion, alternating between 55% and 95% of their predicted maximal oxygen uptake. Each beverage was administered immediately prior to exercise (5 ml · kg-1) and every 15 min thereafter (2 ml · kg-1) until the conclusion of Part A. Results: The performance run times for Part B (mean ± SD) were 16.3 ± 1.5 min (8% CES), 11.1 ± 1.2 min (2.5% CES), 10.0 ± 1.0 min (E) and 9.3 ± 0.9 min (W). The 8% CES beverage produced a significantly greater time to exhaustion (Part B) than the other drinks (5.0 ± 1.5 min, P<0.05). Conclusions: A high CHO concentration formulation (8% CES) is associated with a significant increase in endurance performance during intense, intermittent exercise in recreational, male soccer players.

The six-minute walk test (6-MWT) is widely used to assess functional status in patients with chronic heart failure (CHF). The aims of the present study were: (1) to compare metabolic gas exchange during the 6-MWT in older patients with left ventricular systolic dysfunction (LVSD) and in breathless patients with no major structural heart disease (MSHD); (2) to determine the exercise intensity of the 6-MWT relative to peak oxygen uptake; (3) to establish the accuracy and reproducibility of the Metamax 3B ergospirometer during an incremental workload. Twenty four older patients with LVSD (19 male; age 76 +/- 5 years; BMI 27 +/- 4), and 18 patients with no MSHD (12 male; age 75 +/- 8 years; BMI 27 +/- 4) attended on consecutive days at the same time. Patients completed a 6-MWT with metabolic gas exchange measurements using the Metamax 3B portable ergospirometer, and an incremental cycle ergometry test using both the Metamax 3B and Oxycon Pro metabolic cart. Patients returned and performed a second 6-MWT and an incremental treadmill test, metabolic gas exchange was measured with the Metamax 3B. In patients with LVSD, the 6-MWT was performed at a higher fraction of maximal exercise capacity (p = 0.02). The 6-MWT was performed below the anaerobic threshold in patients with LVSD (83 %) and in patients with no MSHD (61 %). The Metamax 3B showed satisfactory to high accuracy at 10 W and 20 W in patients with LVSD (r = 0.77 - 0.97, p < 0.05), and no MSHD (r = 0.76 - 0.94, p < 0.05). Metabolic gas exchange variables measured during the 6-MWT showed satisfactory to high day-to-day reproducibility in patients with LVSD (ICC = 0.75 - 0.98), but a higher variability was evident in participants with no MSHD (ICC = 0.62 - 0.97). The Metamax 3B portable ergospirometer is an accurate and reproducible device during submaximal, fixed rate exercise in older patients with LVSD and no MSHD. In elderly patients with LVSD and no MSHD, the 6-MWT should not be considered a maximal test of exercise capacity but rather a test of submaximal exercise performance. Our study demonstrates that the 6-MWT takes place at a higher proportion of peak oxygen uptake in patients with LVSD compared to those with no MSHD, and may be one reason why fatigue is a more prominent symptom in these patients.

Background The 6 min walk test (6-MWT) is a simple and popular test for evaluating functional status in patients with chronic heart failure (CHF). However, the prognostic value of the 6-MWT in a large, representative sample of CHF patients, and in patients with different degrees of left ventricular systolic dysfunction (LVSD) remains unclear. Methods and results Of an initial population of 1592 patients, 212 died representing a crude death rate of 13.3%. In surviving patients, the median time to follow-up period was 36.6 months [inter-quartile range (IQR) 28–45 months]. Five variables remained independent predictors of all-cause mortality; decreasing 6-MWT distance, self-perceived signs of breathlessness at night (SOBAN), beta-blocker usage, elevated log NT-proBNP, and reduced haemoglobin concentration. We also dichotomized our analysis by LVSD status (≤mild LVSD or >mild LVSD). For patients with >mild LVSD, 6-MWT remained an important prognostic indicator but not in patients with ≤mild LVSD. Conclusion The 6-MWT is an important independent predictor of mortality in CHF patients, and this was especially evident in patients with >mild LVSD. The 6-MWT provides little prognostic utility in patients with ≤mild LVSD. While log NT-proBNP was the most potent independent predictor, an additive prognostic effect was evident with the additional selection of 6-MWT. Patients' self-perceived symptoms, especially SOBAN was an independent predictor of mortality in our patients.

Rationale: Inadequate protein intake (PI), the main source of essential amino acids (EAAs), and reduced appetite are contributing factors to age-related sarcopenia. The satiating effects of dietary protein may negatively affect energy intake (EI), thus there is a need to explore alternative strategies to facilitate PI without compromising appetite and subsequent EI. Methods: Elderly women completed two experiments (EXP1&2) where they consumed either a Bar (B, 135 kcal) or a Gel (G, 114 kcal), rich in EAAs (7.5 g, 40% L-Leucine), or nothing [control (C)]. In EXP1, subjects (n=10, 68±5 years, mean±SD) consumed B, G or C with appetite sensations and appetite-related hormonal responses monitored for 1h, followed by consumption of an ad libitum breakfast (ALB). In EXP2, subjects (n=11, 69±5 years) ingested B, G or C alongside an ALB. Results: In EXP1, EI at ALB was not different (P=0.674) between conditions (282±135, 299±122, 288±131 kcal for C, B and G respectively). However, total EI was significantly higher in B and G compared to C after accounting for the energy content of the supplements (P<0.0005). Analysis revealed significantly higher appetite Area under the Curve (AUC) (P<0.007), a tendency for higher acylated ghrelin AUC (P=0.087), and significantly lower pancreatic polypeptide AUC (P=0.02) in C compared with B and G. In EXP2, EI at ALB was significantly higher (P=0.028) in C (306±122 kcal) compared to B (245±135 kcal) and G (254±118 kcal). However, total EI was significantly higher in B and G after accounting for the energy content of the supplements (P<0.007). Conclusion: Supplementation with either the bar or gel increased total energy intake whether consumed 1h before or during breakfast. This may represent an effective nutritional means for addressing protein and total energy deficiencies in elderly women.

This study evaluated the effects of the pre-exercise (30 minutes) ingestion of galactose (Gal) or glucose (Glu) on endurance capacity as well as glycemic and insulinemic responses. Ten trained male cyclists completed 3 randomized high-intensity cycling endurance tests. Thirty minutes before each trial, cyclists ingested 1 L of either 40 g of glucose, 40 g of galactose, or a placebo in a double-blind manner. The protocol comprised 20 minutes of progressive incremental exercise (70-85% maximal power output [Wmax]); ten 90-second bouts at 90% Wmax, separated by 180 seconds at 55% Wmax; and 90% Wmax until exhaustion. Blood samples were drawn throughout the protocol. Times to exhaustion were longer with Gal (68.7 ± 10.2 minutes, p = 0.005) compared with Glu (58.5 ± 24.9 minutes), with neither being different to placebo (63.9 ± 16.2 minutes). Twenty-eight minutes after Glu consumption, plasma glucose and serum insulin concentrations were higher than with Gal and placebo (p < 0.001). After the initial 20 minutes of exercise, plasma glucose concentrations increased to a relative hyperglycemia during the Gal and placebo, compared with Glu condition. Higher plasma glucose concentrations during exercise, and the attenuated serum insulin response at rest, may explain the significantly longer times to exhaustion produced by Gal compared with Glu. However, neither carbohydrate treatment produced significantly longer times to exhaustion than placebo, suggesting that the pre-exercise ingestion of galactose and glucose alone is not sufficient to support this type of endurance performance.

The potential for imprecision in the estimation of hydration status from changes in body mass has been outlined previously but the equations derived from these derivations appear inconsistent. Reconciliation of body mass loss in terms of sweat loss and effective body water loss is possible from specific equation sets provided that gains and losses of both body mass and water used in the derivation of sweat loss and to derive effective body water loss are in inclusive equation sets. This is obligatory so that mass and water changes as quantifiable determinants are consistent with both internal processes and external gains and losses. Thus, body mass loss, substrate oxidation, metabolic water, and all the terms used in simultaneous equation sets have to be reconciled not only as identical variables but mathematically balance exactly. The revised equation for effective body water loss given here is different from that originally proposed. Metabolic water is part of body mass loss corrected for substrate oxidation, fluid ingestion, and respiratory water to derive sweat loss and it may not be justified to also include water associated with glycogen as releasable bound water. Accordingly, our calculated effective body water loss is substantially a greater loss than originally supposed but clearly still less than the simple balance between mass loss and fluid ingested.

The addition of carbohydrate (CHO) to an acute creatine (Cr) loading regimen has been shown to increase muscle total creatine content significantly beyond that achieved through creatine loading alone. However, the potential ergogenic effects of combined Cr and CHO loading have not been assessed. The purpose of this study was to compare swimming performance, assessed as mean swimming velocity over repeated maximal intervals, in high-performance swimmers before and after an acute loading regimen of either creatine alone (Cr) or combined creatine and carbohydrate (Cr + CHO). Ten swimmers (mean ± SD of age and body mass: 17.8 ± 1.8 years and 72.3 ± 6.8 kg, respectively) of international caliber were recruited and were randomized to 1 of 2 groups. Each swimmer ingested five 5 g doses of creatine for 4 days, with the Cr + CHO group also ingesting ∼100 g of simple CHO 30 minutes after each dose of creatine. Performance was measured on 5 separate occasions: twice at "baseline" (prior to intervention, to assess the repeatability of the performance test), within 48 hours after intervention, and then 2 and 4 weeks later. All subjects swam faster after either dietary loading regimen (p < 0.01, both regimens); however, there was no difference in the extent of improvement of performance between groups. In addition, all swimmers continued to produce faster swim times for up to 4 weeks after intervention. Our findings suggest that no performance advantage was gained from the addition of carbohydrate to a creatine-loading regimen in these high-caliber swimmers. © 2005 National Strength & Conditioning Association.

Introduction There appears to be a dose dependent curvilinear exercise performance response to ingested carbohydrate (CHO), with an optimum of 78 g/h (Smith et al., 2013). However, the physiological mechanisms underpinning performance gains are unclear and fuel use responses to glucose and mixtures including fructose have not been investigated fully. This study investigated the effect of CHO dose on fuel selection during exercise, in particular exogenous and endogenous (liver and muscle) CHO oxidation. Methods Ten trained male cyclists (VO2max: 61.6 ± 7.4 ml/kg/min) cycled on 4 occasions at 77% VO2max for 2 hours after an overnight fast. From 15 min into exercise and every 15 min thereafter, either 60 g/h glucose (LG), 75 g/h glucose (HG), 90 g/h glucose/fructose (LGF; 2:1 ratio) or 112.5 g/h glucose/fructose (HGF; 2:1 ratio) was ingested in a double-blind randomised order. The formulations contained 13C tracers and were designed to saturate and over saturate intestinal transporters for each hexose. Total, exogenous, endogenous (muscle and liver) CHO oxidation, and total fat oxidation were computed using indirect calorimetry and isotope ratio mass spectrometry. Results Total CHO oxidation was elevated, and total fat oxidation suppressed in HGF relative to all other conditions (CHO 24.9-41.8 g/h higher, Fat 7.9-11.3 g/h lower: both ES > 0.78). Exogenous oxidation was unchanged with higher dose glucose (LG = 41.2, HG = 41.4 g/h, ES = 0.02) and reduced with higher dose glucose/fructose (LGF = 67.7, HGF = 59.2 g/h ES = 0.48). Increasing CHO dose beyond intestinal saturation increased muscle glycogen utilisation for both glucose and glucose/fructose ingestion (125.1±22.6 vs. 109.9±26.9 g/h for glucose, ES=0.59; 129.5±22.6 vs. 100.3±23.1 g/h for glucose/fructose, ES=1.28). Liver glycogen oxidation was reduced with LG vs. HG (20.9±5.6 vs. 24.4±10.1 g/h; ES=0.43), but increased with HGF vs. LGF (30.5±17.7 vs. 19.3±9.4 g/h; ES=0.43). Discussion Increasing CHO ingestion rate for each hexose was not associated with higher exogenous oxidation. When the CHO dose was increased for both glucose and glucose/fructose, endogenous glycogen oxidation was increased, primarily due to an increased reliance on muscle glycogen. This with high liver glycogen and reduced fat oxidation for very high dose glucose/fructose is not ideal for exercise performance. References Smith J, Pascoe D Passe D, Ruby B, Stewart L, Baker L, Zachwieja J (2013). Curvilinear Dose-Response Relationship of Carbohydrate (0-120g/h) and Performance. Med Sci Sports Exerc 45(2): 336-341

Purpose: This study investigated the effect of carbohydrate supplementation on substrate oxidation during exercise in hypoxia after pre-exercise breakfast consumption and omission. Methods: Eleven men walked in normobaric hypoxia (FiO2 ~11.7%) for 90-min at 50% of hypoxic V̇O2max. Participants were supplemented with a carbohydrate beverage (1.2g·min-1 glucose) and a placebo beverage (both enriched with U-13C6 D-glucose) after breakfast consumption and after omission. Indirect calorimetry and isotope ratio mass spectrometry were used to calculate carbohydrate (exogenous and endogenous (muscle and liver)) and fat oxidation. Results: In the first 60-min of exercise, there was no significant change in relative substrate oxidation in the carbohydrate compared with placebo trial after breakfast consumption or omission (both p = 0.99). In the last 30-min of exercise, increased relative carbohydrate oxidation occurred in the carbohydrate compared with placebo trial after breakfast omission (44.0 ± 8.8 vs. 28.0 ± 12.3, p < 0.01) but not consumption (51.7 ± 12.3 vs. 44.2 ± 10.4, p = 0.38). In the same period, a reduction in relative liver (but not muscle) glucose oxidation was observed in the carbohydrate compared with placebo trials after breakfast consumption (liver: 7.7 ± 1.6% vs. 14.8 ± 2.3%, p < 0.01; muscle: 25.4 ± 9.4% vs. 29.4 ± 11.1%, p = 0.99) and omission (liver: 3.8 ± 0.8% vs. 8.7 ± 2.8%, p < 0.01; muscle: 19.4 ± 7.5% vs. 19.2 ± 12.2%, p = 0.99). No significant difference in relative exogenous carbohydrate oxidation was observed between breakfast consumption and omission trials (p = 0.14). Conclusion: In acute normobaric hypoxia, carbohydrate supplementation increased relative carbohydrate oxidation during exercise (> 60 min) after breakfast omission, but not consumption.

Purpose: This study evaluated whether glycogen-associated water is a protected entity not subject to normal osmotic homeostasis. An investigation into practical and theoretical aspects of the functionality of this water as a determinant of osmolality, dehydration, and glycogen concentration was undertaken. Methods: In vitro experiments were conducted to determine the intrinsic osmolality of glycogen–potassium phosphate mixtures as would be found intra-cellularly at glycogen concentrations of 2% for muscle and 5 and 10% for liver. Protected water would not be available to ionic and osmotic considerations, whereas free water would obey normal osmotic constraints. In addition, the impact of 2 L of sweat loss in situations of muscle glycogen repletion and depletion was computed to establish whether water associated with glycogen is of practical benefit (e.g., to increase “available total body water”). Results: The osmolality of glycogen–potassium phosphate mixtures is predictable at 2% glycogen concentration (predicted 267, measured 265.0 ± 4.7 mOsmol kg

−1

This study investigated the effect of carbohydrate (CHO) dose and composition on fuel selection during exercise, specifically exogenous and endogenous (liver and muscle) CHO oxidation. Ten trained males cycled in a double-blind randomized order on 5 occasions at 77% VO2max for 2 h, followed by a 30-min time-trial (TT) while ingesting either 60 g h 1 (LG) or 75 g h 1 13Cglucose (HG), 90 g h 1 (LGF) or 112.5 g h 1 13C-glucose-13C-fructose ([2:1] HGF) or placebo. CHO doses met or exceed reported intestinal transporter saturation for glucose and fructose. Indirect calorimetry and stable mass isotope [13C] tracer techniques were utilized to determine fuel use. TT performance was 93% “likely/probable” to be improved with LGF compared with the other CHO doses. Exogenous CHO oxidation was higher for LGF and HGF compared with LG and HG (ES > 1.34, P < 0.01), with the relative contribution of LGF (24.5 5.3%) moderately higher than HGF (20.6 6.2%, ES = 0.68). Increasing CHO dose beyond intestinal saturation increased absolute (29.2 28.6 g h 1, ES = 1.28, P = 0.06) and relative muscle glycogen utilization (9.2 6.9%, ES = 1.68, P = 0.014) for glucose-fructose ingestion. Absolute muscle glycogen oxidation between LG and HG was not significantly different, but was moderately higher for HG (ES = 0.60). Liver glycogen oxidation was not significantly different between conditions, but absolute and relative contributions were moderately attenuated for LGF (19.3 9.4 g h 1, 6.8 3.1%) compared with HGF (30.5 17.7 g h 1, 10.1 4.0%, ES = 0.79 & 0.98). Total fat oxidation was suppressed in HGF compared with all other CHO conditions (ES > 0.90, P = 0.024–0.17). In conclusion, there was no linear dose response for CHO ingestion, with 90 g h 1 of glucose-fructose being optimal in terms of TT performance and fuel selection.

Background: A recent commentary has been published on our meta-analysis, which investigated substrate oxidation during exercise matched for relative intensities in hypoxia compared with normoxia. Within this commentary, the authors proposed that exercise matched for absolute intensities in hypoxia compared with normoxia, should have been included within the analysis, as this model provides a more suitable experimental design when considering nutritional interventions in hypoxia. Main body: Within this response, we provide a rationale for the use of exercise matched for relative intensities in hypoxia compared with normoxia. Specifically, we argue that this model provides a physiological stimulus replicable of real world situations, by reducing the absolute workload undertaken in hypoxia. Further, the use of exercise matched for relative intensities isolates the metabolic response to hypoxia, rather than the increased relative exercise intensity experienced in hypoxia when utilising exercise matched for absolute intensities. In addition, we also report previously unpublished data analysed at the time of the original meta-analysis, assessing substrate oxidation during exercise matched for absolute intensities in hypoxia compared with normoxia. Conclusion: An increased reliance on carbohydrate oxidation was observed during exercise matched for absolute intensities in hypoxia compared with normoxia. These data now provide a comparable dataset for the use of researchers and practitioners alike in the design of nutritional interventions for relevant populations.

A learning game has been developed which allows learners to study and learn about the significance of three important variables in human physiology (lactate, glycogen, and hydration) and their influence on sports performance during running. The player can control the speed of the runner, and as a consequence the resulting physiological processes are simulated in real-time. The performance degradation of the runner due to these processes requires that different strategies for pacing the running speed are applied by the player, depending on the total length of the run. The game has been positively evaluated in a real learning context of academic physiology teaching.

We investigated the effect of an acute creatine loading (25 g per day for 4 days) and longer-term creatine supplementation (5 g of creatine or 5 g of placebo per day for 2 months) on the performance of 22 elite swimmers during maximal interval sessions. After the acute creatine loading, the mean of the average interval swim times for all swimmers (n = 22) improved (44.3 +/- 16.5 s before vs 43.7 +/- 16.3 s after supplementation; P ≪ 0.01). Three of the 22 swimmers did not respond positively to supplementation. After 2 months of longer term creatine supplementation or placebo,neither group showed a significant change in swimming performance (38.7 +/-13.5 s before vs 38.7 +/- 14.1 s after for the creatine group; 48.7 +/- 18.0 s before vs 48.7 +/- 18.1 s after for the placebo group). We conclude that, in elite swimmers, 4 days of acute creatine loading improves swimming performance significantly when assessed by maximal interval sessions. However, longer-term supplementation for 2 months (5 g of creatine per day) did not benefit significantly the creatine group compared with the placebo group.

It is well-recognised that some female endurance athletes have low bone mineral density (BMD) and increased risk of fracture. Other studies (Hetland et al., 1993: Journal of Clinical Endocrinology and Metabolism, 77, 770–775) have identified that male endurance athletes may also have low BMD. The aim of this study was to examine differences in whole body, lumbar spine and total hip BMD in male and female endurance runners. Following approval from a Local Regional Ethics Committee; 68 endurance runners (35 males, 33 females, aged 19–55 years) undertaking more than 30 miles per week for >3 years, were recruited to the study. Participants with any condition affecting bone metabolism were excluded. Participant demographics and menstrual status were assessed with a screening questionnaire, and body mass and height were measured. Body composition, whole body, lumbar spine (L2–L4), and total hip BMD, were measured using dual X-ray absorptiometry (iDXA, GE Lunar, UK). Absolute and standardised (age, weight, ethnicity) values were used in the analyses. Low BMD was classified as a Z-score of -1.0 or less. Low BMD at the lumbar spine was evident in four male runners and six female runners. Low whole body and total hip BMD was restricted to one female and male, respectively. Mean Z scores for the male athletes were +0.71, s=0.11 for whole body, +0.08, s=0.91 at the spine and +0.51, s=0.82 at the hip. Comparative values in females were +0.91, s=0.12, -0.31, s=0.72, and +0.65, s=0.85 respectively. Four of the six females with low lumbar spine BMD were amenorrheic/ oligomenorrheic. This was not significantly different to the 8 out of 27 amenorrheic/ oligomenorrheic females with normal lumbar spine BMD (Pearson Chi-squared P=0.12). Independent t-tests showed significant differences between sex for absolute whole body (P=0.00), lumbar spine (P=0.01) and total hip values (P=0.02). There were no significant sex differences for whole body (P=0.91), lumbar spine (P=0.36) or total hip BMD (P=0.18), following adjustment for differences in age, body mass, height and body fat content. These findings indicate lower BMD exists at the lumbar spine (but not whole body or hip) among male and female runners. The impact experienced across the hip joint during running may offer some protection against bone loss. A higher proportion of females exhibited low lumbar spine BMD – possibly associated with menstrual irregularities. Further research is needed to evaluate determinants of low BMD in male athletes.

PURPOSE: Beneficial effects of carbohydrate (CHO) ingestion on exogenous CHO oxidation and endurance performance require a well-functioning gastrointestinal (GI) tract. However, GI complaints are common during endurance running. This study investigated the effect of a CHO solution-containing sodium alginate and pectin (hydrogel) on endurance running performance, exogenous and endogenous CHO oxidation and GI symptoms. METHODS: Eleven trained male runners, using a randomised, double-blind design, completed three 120-minute steady state runs at 68% V̇O2max, followed by a 5-km time-trial. Participants ingested 90 g·h-1 of 2:1 glucose:fructose (13C enriched) either as a CHO hydrogel, a standard CHO solution (non-hydrogel), or a CHO-free placebo during the 120 minutes. Fat oxidation, total and exogenous CHO oxidation, plasma glucose oxidation and endogenous glucose oxidation from liver and muscle glycogen were calculated using indirect calorimetry and isotope ratio mass spectrometry. GI symptoms were recorded throughout the trial. RESULTS: Time-trial performance was 7.6% and 5.6% faster after hydrogel ([minutes:seconds]19:29±2:24; p<0.001) and non-hydrogel (19:54±2:23, p=0.002), respectively, versus placebo (21:05±2:34). Time-trial performance after hydrogel was 2.1% faster (p=0.033) than non-hydrogel. Absolute and relative exogenous CHO oxidation was greater with hydrogel (68.6±10.8g, 31.9±2.7%; p=0.01) versus non-hydrogel (63.4±8.1g, 29.3±2.0%; p=0.003). Absolute and relative endogenous CHO oxidation were lower in both CHO conditions compared with placebo (p<0.001), with no difference between CHO conditions. Absolute and relative liver glucose and muscle glycogen oxidation were not different between CHO conditions. Total GI symptoms were not different between hydrogel and placebo, but GI symptoms was higher in non-hydrogel compared with placebo and hydrogel (p<0.001). CONCLUSION: Ingestion of glucose and fructose in hydrogel form during running benefited endurance performance, exogenous CHO oxidation and GI symptoms, compared with a standard CHO solution.

Purpose This study investigated the effect of small manipulations in carbohydrate (CHO) dose on exogenous and endogenous (liver and muscle) fuel selection during exercise. Method Eleven trained males cycled in a double-blind randomised order on 4 occasions at 60% V˙O2max for 3 h, followed by a 30-min time-trial whilst ingesting either 80 g h−1 or 90 g h−1 or 100 g h−1 13C-glucose-13C-fructose [2:1] or placebo. CHO doses met, were marginally lower, or above previously reported intestinal saturation for glucose–fructose (90 g h−1). Indirect calorimetry and stable mass isotope [13C] techniques were utilised to determine fuel use. Result Time-trial performance was 86.5 to 93%, ‘likely, probable’ improved with 90 g h−1 compared 80 and 100 g h−1. Exogenous CHO oxidation in the final hour was 9.8–10.0% higher with 100 g h−1 compared with 80 and 90 g h−1 (ES = 0.64–0.70, 95% CI 9.6, 1.4 to 17.7 and 8.2, 2.1 to 18.6). However, increasing CHO dose (100 g h−1) increased muscle glycogen use (101.6 ± 16.6 g, ES = 0.60, 16.1, 0.9 to 31.4) and its relative contribution to energy expenditure (5.6 ± 8.4%, ES = 0.72, 5.6, 1.5 to 9.8 g) compared with 90 g h−1. Absolute and relative muscle glycogen oxidation between 80 and 90 g h−1 were similar (ES = 0.23 and 0.38) though a small absolute (85.4 ± 29.3 g, 6.2, − 23.5 to 11.1) and relative (34.9 ± 9.1 g, − 3.5, − 9.6 to 2.6) reduction was seen in 90 g h−1 compared with 100 g h−1. Liver glycogen oxidation was not significantly different between conditions (ES < 0.42). Total fat oxidation during the 3-h ride was similar in CHO conditions (ES < 0.28) but suppressed compared with placebo (ES = 1.05–1.51). Conclusion ‘Overdosing’ intestinal transport for glucose–fructose appears to increase muscle glycogen reliance and negatively impact subsequent TT performance.

This study assessed the potential physiological and perceptual drivers of fluid intake (FI) and thirst sensation (TS) during intermittent exercise. 10 male rugby players (17 ± 1 years, stature: 179.1 ± 4.2 cm, body mass (BM): 81.9 ± 8.1 kg) participated in 6x6 min small-sided games, interspersed with 2 min rest, where FI was ad libitum during rest periods. Pre and post measurements of BM, subjective ratings (thirst, thermal comfort, thermal sensation, mouth dryness), plasma osmolality (POsm), serum sodium concentration (S[Na+]), haematocrit and haemoglobin (to calculate plasma volume change; PV) were taken. FI was measured during rest periods. BM change was -0.17 ± 0.59% and FI was 0.88 ± 0.38L. Pre to post POsm decreased (-3.1 ± 2.3 mOsm·kg−1; p = 0.002) and S[Na+] remained similar (-0.3 ± 0.7mmol·L-1, p = 0.193). ∆PV was 5.84 ± 3.65%. FI displayed a relationship with pre POsm (r = -0.640, p = 0.046), pre thermal comfort (r = 0.651; p = -0.041), ∆S[Na+] (r = 0.816, p = 0.004), and ∆PV (r = 0.740; p = 0.014). ∆TS displayed a relationship with pre mouth dryness (r = 0.861, p = 0.006) and ∆mouth dryness (r = 0.878, p = 0.004). Yet a weak positive relationship between ∆TS and FI was observed (r = 0.085, p = 0.841). These data observed in an ambient temperature of 13.6 ± 0.9̊C, suggest team sport athletes drink in excess of fluid homeostasis requirements and TS in cool conditions, however this was not influence by thermal discomfort.

Acute Mountain Sickness (AMS) is a common clinical challenge at high altitude (HA). A point-of-care biochemical marker for AMS could have widespread utility. Neutrophil gelatinase-associated lipocalin (NGAL) rises in response to renal injury, inflammation and oxidative stress. We investigated whether NGAL rises with HA and if this rise was related to AMS, hypoxia or exercise. NGAL was assayed in a cohort (n = 22) undertaking 6 hours exercise at near sea-level (SL); a cohort (n = 14) during 3 hours of normobaric hypoxia (FiO2 11.6%) and on two trekking expeditions (n = 52) to over 5000 m. NGAL did not change with exercise at SL or following normobaric hypoxia. During the trekking expeditions NGAL levels (ng/ml, mean ± sd, range) rose significantly (P < 0.001) from 68 ± 14 (60-102) at 1300 m to 183 ± 107 (65-519); 143 ± 66 (60-315) and 150 ± 71 (60-357) at 3400 m, 4270 m and 5150 m respectively. At 5150 m there was a significant difference in NGAL between those with severe AMS (n = 7), mild AMS (n = 16) or no AMS (n = 23): 201 ± 34 versus 171 ± 19 versus 124 ± 12 respectively (P = 0.009 for severe versus no AMS; P = 0.026 for mild versus no AMS). In summary, NGAL rises in response to prolonged hypobaric hypoxia and demonstrates a relationship to the presence and severity of AMS.

Rationale: Inadequate protein intake (PI), the main source of essential amino acids (EAAs), and reduced appetite are contributing factors to age-related sarcopenia. The satiating effects of dietary protein may negatively affect energy intake (EI), thus there is a need to explore alternative strategies to facilitate PI without compromising appetite and subsequent EI. Methods: Elderly women completed two experiments (EXP1&2) where they consumed either a Bar (B, 135 kcal) or a Gel (G, 114 kcal), rich in EAAs (7.5 g, 40% L-Leucine), or nothing [control (C)]. In EXP1, subjects (n=10, 68±5 years, mean±SD) consumed B, G or C with appetite sensations and appetite-related hormonal responses monitored for 1h, followed by consumption of an ad libitum breakfast (ALB). In EXP2, subjects (n=11, 69±5 years) ingested B, G or C alongside an ALB. Results: In EXP1, EI at ALB was not different (P=0.674) between conditions (282±135, 299±122, 288±131 kcal for C, B and G respectively). However, total EI was significantly higher in B and G compared to C after accounting for the energy content of the supplements (P<0.0005). Analysis revealed significantly higher appetite Area under the Curve (AUC) (P<0.007), a tendency for higher acylated ghrelin AUC (P=0.087), and significantly lower pancreatic polypeptide AUC (P=0.02) in C compared with B and G. In EXP2, EI at ALB was significantly higher (P=0.028) in C (306±122 kcal) compared to B (245±135 kcal) and G (254±118 kcal). However, total EI was significantly higher in B and G after accounting for the energy content of the supplements (P<0.007). Conclusion: Supplementation with either the bar or gel increased total energy intake whether consumed 1h before or during breakfast. This may represent an effective nutritional means for addressing protein and total energy deficiencies in elderly women.

Background: Inadequate protein intake (PI), containing a sub-optimal source of essential amino acids (EAAs), and reduced appetite are contributing factors to age-related sarcopenia. The satiating effects of dietary protein per se may negatively affect energy intake (EI), thus there is a need to explore alternative strategies to facilitate PI without compromising appetite and subsequent EI. Methods: Older women completed two experiments (EXP1 and EXP2) where they consumed either a Bar (565 kJ), a Gel (477 kJ), both rich in EAAs (7.5 g, 40% L-leucine), or nothing (Control). In EXP1, participants (n=10, 68±5 years, mean±SD) consumed Bar, Gel or Control with appetite sensations and appetite-related hormonal responses monitored for one hour, followed by consumption of an ad libitum breakfast (ALB). In EXP2, participants (n=11, 69±5 years) ingested Bar, Gel or Control alongside an ALB. Results: In EXP1, EI at ALB was not different (P=0.674) between conditions (1179±566, 1254±511, 1206±550 kJ for the Control, Bar, and Gel respectively). However, total EI was significantly higher in the Bar and Gel compared to the Control after accounting for the energy content of the supplements (P<0.0005). Analysis revealed significantly higher appetite Area under the Curve (AUC) (P<0.007), a tendency for higher acylated ghrelin AUC (P=0.087), and significantly lower pancreatic polypeptide AUC (P=0.02) in the Control compared with the Bar and Gel. In EXP2, EI at ALB was significantly higher (P=0.028) in the Control (1282±513 kJ) compared to the Bar (1026±565 kJ) and Gel (1064±495 kJ). However, total EI was significantly higher in the Bar and Gel after accounting for the energy content of the supplements (P<0.007). Conclusions: Supplementation with either the Bar or Gel increased total energy intake whether consumed one hour before or during breakfast. This may represent an effective nutritional means for addressing protein and total energy deficiencies in older women.

Background: Prevalence of the metabolic syndrome has risen in children from 4.2% to 6.4% in 8 years (Duncan et al., 2004). Given this and the evidence that dietary modification and physical activity can favourably modify cardiovascular risk factors, the current study assessed the impact of an 8-week residential weight loss camp intervention on various biochemical and body composition variables. Methods: Fifty-one overweight and obese children (19 boys and 32 girls), mean age of 14.4 ± 2.0 years, BMI of 33.7 ± 7.2 kg/m2 and waist circumference of 95.5 ± 13.3 cm were resident at the camp intervention. Body composition and a range of biochemical variables were measured before and after the intervention (mean stay 31 ± 13 days). Results: Significant reductions (P < 0.001) were observed in all body composition variables, with BMI and waist circumference reduced by 5.6% and 5%, respectively. Significant reductions (P < 0.01) were observed for all biochemical variables except adiponectin. The following changes were achieved, T-C/HDL-c ratio (3.54 ± 0.76 pre to 2.99 ± 0.64 post), triglycerides (1.06 ± 0.41 mmol/L pre to 0.83 ± 0.32 mmol/L post), HOMA-IR (measure of insulin resistance) (3.46 ± 2.27 pre to 2.72 ± 1.77 post), C-reactive protein (measure of inflammation) (3.06 ± 2.79 mg/L pre to 1.71 ± 2.06 mg/L post), and leptin (125.0 ± 69.3 ng/mL pre to 55.7 ± 50.5 ng/mL post). Conclusion: Our programme achieved significant improvements in a variety of bio-chemical and body composition variables in a matter of weeks. This demonstrates the potential of this form of intervention for acute improvements. Further research is required to investigate the durability of these effects and the relationship with morbidity and premature mortality in adulthood.

This study evaluated the effects of inspiratory muscle training (IMT) on inspiratory muscle fatigue (IMF) and physiological and perceptual responses during trekking-specific exercise. An 8-week IMT program was completed by 21 males (age 32.4 ± 9.61 years, VO2peak 58.8 ± 6.75 mL/kg/min) randomised within matched pairs to either the IMT group (n = 11) or the placebo group [(P), n = 9]. Twice daily, participants completed 30 (IMT) or 60 (P) inspiratory efforts using a Powerbreathe initially set at a resistance of 50% (IMT) or used at 15% (P) of maximal inspiratory pressure (MIP) throughout. A loaded (12.5 kg) 39-minute incremental walking protocol (3–5 km/hour and 1–15% gradient) was completed in normobaric hypoxia (PIO2 = 110 mmHg, 3000 m) before and after training. MIP increased from 164 to 188 cmH2O (18%) and from 161 to 171 cmH2O (6%) in the IMT and P groups (P = 0.02). The 95% CI for IMT showed a significant improvement in MIP (5.21±43.33 cmH2O), but not for P. IMF during exercise (MIP) was*5%, showing no training effect for either IMT or P (P = 0.23). Rating of perceived exertion (RPE) was consistently reduced (*1) throughout exercise following training for IMT, but not for P (P = 0.03). The mean blood lactate concentration during exercise was significantly reduced by 0.26 and 0.15 mmol/L in IMT and P (P = 0.00), with no differences between groups (P = 0.34). Rating of dyspnoea during exercise decreased (*0.4) following IMT but increased (*0.3) following P (P = 0.01). IMT may attenuate the increased physiological and perceived exercise stress experienced during normobaric hypoxia, which may benefit moderate altitude expeditions

The effects of inspiratory muscle training (IMT) were evaluated at rest and during exercise in normobaric hypoxia (NH) and then an 11-day trek to 5300m. A 7-week IMT program was completed by 6 females and 3 males (age 34.8 ± 10.0 years) randomized to IMT (n = 4) or placebo [P (n = 5)]. A Powerbreathe was initially set at a resistance of 50% (IMT) or used at 15%ofmaximal inspiratory pressure (MIP) throughout (P). A self-paced walking test was completed before and after training at PIO2 = 104.1mmHg, 3440m (NH1); PIO2 = 85.9 mmHg, 4930m (NH2); and at 3440m during the trek (HH). Exercise data were interpolated to 4.8 km/hour to evaluate training effects. Patterns of change suggest possible benefits of IMT, but due to small group sizes and variability, these trends are not significant. MIP increased by 6% and 4% following IMT and P. Pulse oxygen saturation (SaO2) during exercise in NH2 increased by*4% following IMT, with no change in P. Decreases in resting SaO2 during the expedition (4930m) were attenuated in IMT (85.0 ± 3.61%) compared to P (80.0 ± 5.87%). Comparisons between NH1 exercise post-training and HH showed a decrease in perceived dyspnoea and effort in IMT ( - 0.3 and - 0.7) but an increase in P ( + 0.7 and + 2.6). Nonsignificant trends within the data suggest that the altitude-induced decrease in resting and exercise SaO2 and intensified perceived effort and dyspnoea during exercise were attenuated following IMT. However, further research is required to establish any beneficial effect of IMT.

BACKGROUND: A recent commentary has been published on our meta-analysis, which investigated substrate oxidation during exercise matched for relative intensities in hypoxia compared with normoxia. Within this commentary, the authors proposed that exercise matched for absolute intensities in hypoxia compared with normoxia, should have been included within the analysis, as this model provides a more suitable experimental design when considering nutritional interventions in hypoxia. MAIN BODY: Within this response, we provide a rationale for the use of exercise matched for relative intensities in hypoxia compared with normoxia. Specifically, we argue that this model provides a physiological stimulus replicable of real world situations, by reducing the absolute workload undertaken in hypoxia. Further, the use of exercise matched for relative intensities isolates the metabolic response to hypoxia, rather than the increased relative exercise intensity experienced in hypoxia when utilising exercise matched for absolute intensities. In addition, we also report previously unpublished data analysed at the time of the original meta-analysis, assessing substrate oxidation during exercise matched for absolute intensities in hypoxia compared with normoxia. CONCLUSION: An increased reliance on carbohydrate oxidation was observed during exercise matched for absolute intensities in hypoxia compared with normoxia. These data now provide a comparable dataset for the use of researchers and practitioners alike in the design of nutritional interventions for relevant populations.

Introduction The hypoxic exposure experienced at altitude is known to impair endurance performance, which may in part be related to changes in substrate utilisation. However, equivocal findings have been reported regarding the contribution of carbohydrate and fat to the total energy yield in hypoxia. These divergent findings may be due to differences in methodological design, such as the nutritional status of participants prior to exercise. As such, this study was the first to investigate the effect of the fasted and fed state on substrate utilisation during exercise in normoxia and normobaric hypoxia. Methods Twelve men rested and performed exercise twice in sea level (SL) conditions (~20.93% O2) and twice at normobaric hypoxia (NH) equivalent to 4300m (Fi02~11.7%) in a randomised, crossover design. Participants entered the chamber after an overnight fast. After 1 hour, one trial within each experimental condition remained fasted, while the other included consumption of a high carbohydrate breakfast (567 kcal, 68% carbohydrate, 12% fat, 20% protein). One hour after consumption of breakfast (fed trials) or no breakfast (fasted trials), participants walked for one hour at intensities of 40%, 50% and 60% of altitude specific VO2max. Walking was performed on a treadmill at 10-15% gradient whilst carrying a 10kg backpack to simulate altitude trekking. Expired gas was measured throughout, using online gas analysis for the quantification of carbohydrate and fat oxidation. Results Relative carbohydrate oxidation was significantly reduced in NH fasted conditions compared with SL fasted conditions at 40% (SL fasted: 38.5±15.5%; NH fasted: 22.4±17.5%; p = 0.03) and 60% VO2max (SL fasted: 50.1±17.6%; NH fasted: 35.4±12.4%; p = 0.03), with a trend observed at 50% VO2max (SL fasted: 38.0±17.0%; NH fasted: 23.6±17.9%; p = 0.07). Relative fat oxidation in the fasted state was reciprocal to the fasted relative carbohydrate findings at all intensities. No significant differences in relative carbohydrate oxidation were observed in NH fed conditions compared with SL fed conditions at 40% (SL fed: 48.5±13.3%; NH fed: 44.1±20.6%; p = 0.99), 50% (SL fed: 47.1±14.0%; NH fed: 43.1±11.7%; p = 0.99) and 60% VO2max (SL fed: 55.1±15.0%; NH fed: 54.6±17.8%; p = 0.99). Relative fat oxidation in the fed state was reciprocal to the fed relative carbohydrate findings at all intensities. Conclusion This study is the first to establish that relative carbohydrate contributions to energy expenditure decrease, while relative fat contributions increase, during exercise matched for relative intensities in NH compared with SL when in the fasted, but not fed state. These findings suggest that the feeding state of participants may explain some of the divergence within the current literature regarding the effects of hypoxia on substrate utilisation. Further, these findings should be considered when prescribing nutritional support for mountaineers and military personnel trekking at high altitude.

Purpose: Reported substrate oxidation responses in hypoxia are divergent, and may be due to differences in methodological design, such as pre-exercise nutritional status and exercise intensity. This study investigated the effect of breakfast consumption versus omission on substrate oxidation at varying exercise intensities in normobaric hypoxia compared with normoxia. Methods: Twelve participants rested and exercised once after breakfast consumption and once after omission in normobaric hypoxia (4300 m: FiO2 ~11.7%) and normoxia. Exercise consisted of walking for 20-minutes at 40%, 50% and 60% of altitude-specific V̇O2max at 10-15% gradient with a 10 kg backpack. Indirect calorimetry was used to calculate carbohydrate and fat oxidation. Results: The relative contribution of carbohydrate oxidation to energy expenditure was significantly reduced in hypoxia compared with normoxia during exercise after breakfast omission at 40% (22.4 ± 17.5% vs. 38.5±15.5%, p = 0.03) and 60% V̇O2max (35.4±12.4 vs. 50.1±17.6%, p = 0.03), with a trend observed at 50% V̇O2max (23.6±17.9% vs. 38.1± 17.0%, p = 0.07). The relative contribution of carbohydrate oxidation to energy expenditure was not significantly different in hypoxia compared with normoxia during exercise after breakfast consumption at 40% (42.4±15.7% vs. 48.5±13.3%, p = 0.99), 50% (43.1±11.7% vs. 47.1±14.0%, p = 0.99) and 60% V̇O2max (54.6±17.8% vs. 55.1±15.0%, p = 0.99). Conclusions: Relative carbohydrate oxidation was significantly reduced in hypoxia compared with normoxia during exercise after breakfast omission but not during exercise after breakfast consumption. This response remained consistent with increasing exercise intensities. These findings may explain some of the disparity in the literature

Purpose: The purpose of experiment one was to determine the appetite, acylated ghrelin and energy intake response to breakfast consumption and omission in hypoxia and normoxia. Experiment two aimed to determine the appetite, acylated ghrelin and energy intake response to carbohydrate supplementation after both breakfast consumption and omission in hypoxia. Methods: In experiment one, twelve participants rested and exercised once after breakfast consumption and once after omission in normobaric hypoxia (4300 m: FiO2 ~11.7%) and normoxia. In experiment two, eleven participants rested and exercised in normobaric hypoxia (4300 m: FiO2 ~11.7%), twice after consuming a high carbohydrate breakfast and twice after breakfast omission. Participants consumed both a carbohydrate (1.2g·min

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This study evaluated the effects of inspiratory muscle training (IMT) on inspiratory muscle fatigue (IMF) and physiological and perceptual responses during trekking-specific exercise. An 8-week IMT program was completed by 21 males (age 32.4 – 9.61 years, VO2peak 58.8 – 6.75 mL/kg/min) randomised within matched pairs to either the IMT group (n = 11) or the placebo group [(P), n = 9]. Twice daily, participants completed 30 (IMT) or 60 (P) inspiratory efforts using a Powerbreathe initially set at a resistance of 50% (IMT) or used at 15% (P) of maximal inspiratory pressure (MIP) throughout. A loaded (12.5 kg) 39-minute incremental walking protocol (3–5 km/hour and 1–15% gradient) was completed in normobaric hypoxia (PIO2 = 110 mmHg, 3000 m) before and after training. MIP increased from 164 to 188 cmH2O (18%) and from 161 to 171 cmH2O (6%) in the IMT and P groups (P = 0.02). The 95% CI for IMT showed a significant improvement in MIP (5.21–43.33 cmH2O), but not for P. IMF during exercise (MIP) was ~5%, showing no training effect for either IMT or P (P = 0.23). Rating of perceived exertion (RPE) was consistently reduced (~1) throughout exercise following training for IMT, but not for P (P = 0.03). The mean blood lactate concentration during exercise was significantly reduced by 0.26 and 0.15 mmol/L in IMT and P (P = 0.00), with no differences between groups (P = 0.34). Rating of dyspnea during exercise decreased (~0.4) following IMT but increased (~0.3) following P (P = 0.01). IMT may attenuate the increased physiological and perceived exercise stress experienced during normobaric hypoxia, which may benefit moderate altitude expeditions.

The effects of inspiratory muscle training (IMT) were evaluated at rest and during exercise in normobaric hypoxia (NH) and then an 11-day trek to 5300m. A 7-week IMT program was completed by 6 females and 3 males (age 34.8 ± 10.0 years) randomized to IMT (n = 4) or placebo [P (n = 5)]. A Powerbreathe was initially set at a resistance of 50% (IMT) or used at 15% of maximal inspiratory pressure (MIP) throughout (P). A self-paced walking test was completed before and after training at PIO2 = 104.1mmHg, 3440m (NH1); PIO2 = 85.9 mmHg, 4930m (NH2); and at 3440m during the trek (HH). Exercise data were interpolated to 4.8 km/hour to evaluate training effects. Patterns of change suggest possible benefits of IMT, but due to small group sizes and variability, these trends are not significant. MIP increased by 6% and 4% following IMT and P. Pulse oxygen saturation (SaO2) during exercise in NH2 increased by*4% following IMT, with no change in P. Decreases in resting SaO2 during the expedition (4930m) were attenuated in IMT (85.0 ± 3.61%) compared to P (80.0 ± 5.87%). Comparisons between NH1 exercise post-training and HH showed a decrease in perceived dyspnoea and effort in IMT ( - 0.3 and - 0.7) but an increase in P ( + 0.7 and + 2.6). Nonsignificant trends within the data suggest that the altitude-induced decrease in resting and exercise SaO2 and intensified perceived effort and dyspnoea during exercise were attenuated following IMT. However, further research is required to establish any beneficial effect of IMT.

Aim: Small dense LDL particles are associated with an increased risk of coronary heart disease and are prevalent in obesity related dyslipidaemia. This study evaluated the effect of weight loss in nine children (BMI 33.4 +/- 8.4 kg.m(-2) and age 15.1 +/- 2.9 years) on LDL peak particle size, and cholesterol concentrations within particular LDL sub-fractions. Methods: Each child undertook fan based physical activity, dietary restriction and modification and lifestyle education classes in a residential summer weight loss intervention. Blood was drawn before and after intervention and LDL heterogeneity measured by ultracentrifugation. Results: The mean change in body weight were -6.8 +/- 4.9 kg, BMI units -2.5 +/- 1.4 kg.m(-2), and waist circumference -6.3 +/- 6.3 cm (all p < 0.01). Absolute LDL-c concentration reduced from 106.2 mg/dL to 88.3 mg/dL (p < 0.01). The cholesterol contained within the small dense LDL sub-fraction (LDL-c M) reduced from 54.1 mg/dL to 40.4 mg/dL (p < 0.01). Peak particle density decreased from 1.041g/mL to 1.035g/mL (p < 0.01). At pre intervention 50.9% of absolute cholesterol was within LDL-c M particles, changing to 46.2%. Conclusion: Mean weight loss of -6.8 +/- 4.9 kg lowers absolute LDL-c and the cholesterol specifically within LDL-c III particles. LDL peak particle size increased and a degree of LDL particle remodelling occurred. These favourable adaptations, accrued in a matter of 4 weeks, maybe associated with a reduction in CHD risk.

Fluid and sodium balance is important for performance and health; however, limited data in rugby union players exist. The purpose of the study was to evaluate body mass (BM) change (dehydration) and blood[Na] change during exercise. Data were collected from 10 premiership rugby union players, over a 4-week period. Observations included match play (23 subject observations), field (45 subject observations), and gym (33 subject observations) training sessions. Arrival urine samples were analyzed for osmolality, and samples during exercise were analyzed for [Na]. Body mass and blood[Na] were determined pre- and postexercise. Sweat[Na] was analyzed from sweat patches worn during exercise, and fluid intake was measured during exercise. Calculations of fluid and Na loss were made. Mean arrival urine osmolality was 423 ± 157 mOsm·kg, suggesting players were adequately hydrated. After match play, field, and gym training, BM loss was 1.0 ± 0.7, 0.3 ± 0.6, and 0.1 ± 0.6%, respectively. Fluid loss was significantly greater during match play (1.404 ± 0.977 kg) than field (1.008 ± 0.447 kg, p = 0.021) and gym training (0.639 ± 0.536 kg, p < 0.001). Fluid intake was 0.955 ± 0.562, 1.224 ± 0.601, and 0.987 ± 0.503 kg during match play, field, and gym training, respectively. On 43% of observations, players were hyponatremic when BM increased, 57% when BM was maintained, and 35% when there was a BM loss of 0.1-0.9%. Blood[Na] was the representative of normonatremia when BM loss was >1.0%. The findings demonstrate that rugby union players are adequately hydrated on arrival, fluid intake is excessive compared with fluid loss, and some players are at risk of developing hyponatremia.

It is important to employ training practices that ensure that fire-fighter instructors work in an environment which does not provoke unacceptable rises in core temperature (>38°C). PURPOSE: To assess the effects of a two-day fire-behaviour training (FBT) course on the core temperature (Tc) of fire-fighter instructors in order to establish whether current training practices ensure a safe working environment. METHODS: Eleven males (mean±sd age 38.3±4.3 yr, body mass 88.5±12.7 kg and stature 177.8±5.3 cm) from two regional training centres completed three days of standard FBT, wearing full protective clothing and breathing apparatus. Two consecutive days (HOT1 and HOT2, mean ambient temperature of 12.7°C) each consisted of a morning and an afternoon heat exposure (approximately 30 minutes in duration). The third day was a control (NORM), without heat exposure (mean Tc of 19.3 °C). Tc was measured at baseline (BASE) and at the start and end of the two exposures (PRE-AM, POST-AM and PRE-PM, POST-PM respectively) for each subject using a telemetry pill (HQ Inc, USA). RESULTS: There was a different pattern of Tc response over the two HOT days compared with the NORM day due to the significant increase in Tc associated with each of the heat exposures (p<0.01, PRE to POST, Table 1). Mean Tc did not reach 38°C, but in 10 out of 44 individual exposures subjects had a T above 38°C post heat exposure. In contrast, baseline T for the three days was not significantly different and showed a consistent significant increase to PRE-AM values (p<0.01, BASE to PRE-AM, Table 1) associated with the wearing of protective clothing and morning activities. The mean (±sd) unit temperatures of the HOT and NORM days were 160.2 (±89.3) and 27.6 (±8.4) °C respectively. CONCLUSION: The physiological strain experienced due to heat exposure in firefighter instructors resulted in a significant increase in Tc above that experienced during similar physical exertion with no heat exposure. While mean Tc did not reach 38°C, defined as an acceptable limit for work, Tc did rise above 38°C after approximately 1 in 4 individual heat exposures.

This study assessed the reproducibility of performance and selected metabolic variables during a variable high-intensity endurance cycling test. 8 trained male cyclists (age: 35.9 ± 7.7 years, maximal oxygen uptake: 54.3 ± 3.9 mL·kg - 1·min - 1) completed 4 high-intensity cycling tests, performed in consecutive weeks. The protocol comprised: 20 min of progressive incremental exercise, where the power output was increased by 5% maximal workload (Wmax) every 5 min from 70% Wmax to 85% Wmax; ten 90 s bouts at 90% Wmax, separated by 180 s at 55% Wmax; 90% Wmax until volitional exhaustion. Blood samples were drawn and heart rate was monitored throughout the protocol. There was no significant order effect between trials for time to exhaustion (mean: 4 113.0 ± 60.8 s) or total distance covered (mean: 4 6126.2 ± 1 968.7 m). Total time to exhaustion and total distance covered showed very high reliability with a mean coefficient of variation (CV) of 1.6% (95% Confidence Intervals (CI) 0.0 ± 124.3 s) and CV of 2.2% (95% CI 0.0 ± 1904.9 m), respectively. Variability in plasma glucose concentrations across the time points was very small (CV 0.46-4.3%, mean 95% CI 0.0 ± 0.33 to 0.0 ± 0.94 mmol·L - 1). Plasma lactate concentrations showed no test order effect. The reliability of performance and metabolic variables makes this protocol a valid test to evaluate nutritional interventions in endurance cycling.

Limited data exists on the hydration status of female athletes, with no data available on female rugby players. The objective of this study was to investigate the habitual hydration status on arrival, sweat loss, fluid intake, sweat Na loss and blood [Na] during field training and match-play in ten international female rugby league players. Urine osmolality on arrival to match-play (382 ± 302 mOsmol·kg) and training (667 ± 260 mOsmol·kg) was indicative of euhydration. Players experienced a body mass loss of 0.50 ± 0.45 and 0.56 ± 0.53% during match-play and training respectively. During match-play players consumed 1.21 ± 0.43 kg of fluid and had a sweat loss of 1.54 ± 0.48 kg. During training players consumed 1.07 ± 0.90 kg of fluid, in comparison to 1.25 ± 0.83 kg of sweat loss. Blood [Na] was well regulated ([INCREMENT]-0.7 ± 3.4 and [INCREMENT]-0.4 ± 2.6 mmol·L) despite sweat [Na] of 47.8 ± 5.7 and 47.2 ± 6.3 mmol·L during match-play and training. The findings of this study show mean blood [Na] appears to be well regulated despite losses of Na in sweat and electrolyte free fluid consumption. For the duration of the study players did not experience a body mass loss (dehydration >2%) indicative of a reduction in exercise performance, thus habitual hydration strategies appear adequate. Practitioners should evaluation the habitual hydration status of athletes to determine if interventions above habitual strategies are warranted.

A learning game has been developed which allows learners to study and learn about the significance of three important variables in human physiology (lactate, glycogen, and hydration) and their influence on sports performance during running. The player can control the speed of the runner, and as a consequence the resulting physiological processes are simulated in real-time. The performance degradation of the runner due to these processes requires that different strategies for pacing the running speed are applied by the player, depending on the total length of the run. The game has been positively evaluated in a real learning context of academic physiology teaching.

This study aimed to evaluate the weight loss and hunger motivation effects of an energy-restricted high-protein (HP) diet in overweight and obese children. In total, 95 overweight and obese children attended an 8-week (maximum) program of physical activity, reduced-energy intake, and behavior change education. Children were randomly assigned to one of two isoenergetic diets (standard (SP): 15% protein; HP: 25% protein), based on individually estimated energy requirements. Anthropometry and body composition were assessed at the start and end of the program and appetite and mood ratings completed on the first 3 consecutive weekdays of each week children attended camp. The HP diet had no greater effect on weight loss, body composition, or changes in appetite or mood when compared to the SP diet. Overall, campers lost 5.2 3.0 kg in body weight and reduced their BMI standard deviation score (sds) by 0.25. Ratings of desire to eat increased significantly over the duration of the intervention, irrespective of diet. This is the third time we have reported an increase in hunger motivation in weight-loss campers and replicates our previous failure to block this with a higher protein diet. Further work is warranted into the management of hunger motivation as a result of negative energy balance.

Sub-optimal calcium, vitamin D and iron intakes are typical in athletes. However, quantification by dietary intake may be erroneous, with biomarkers providing a more accurate assessment. This study aimed to determine the calcium, vitamin D and iron status of 8 junior (i.e., under-18 [U18]; age 15.5 ± 0.5 years; height 180.4 ± 6.7 cm; body mass 81.6 ± 14.3 kg) and 12 senior (i.e., over-18 [O18]; age 19.7 ± 1.8 years; height 184.9 ± 6.9 cm; body mass 97.4 ± 14.4 kg) male rugby union players, and assess their adequacy against reference values. Fasted serum calcium, 25(OH)D and ferritin concentrations were analysed using Enzyme-Linked Immunosorbent Assay during the in-season period (March-April). U18 had very likely greater calcium concentrations than O18 (2.40 ± 0.08 vs. 2.25 ± 0.19 mmol.l-1). Differences between U18 and O18 were unclear for 25(OH)D (20.21 ± 11.57 vs. 29.02 ± 33.69 nmol.l-1) and ferritin (59.33 ± 34.61 vs. 85.25 ± 73.53 µg.l-1). Compared to reference values, all U18 had adequate serum calcium concentrations, whereas 33% and 67% of O18 were deficient and adequate, respectively. All U18 and 83% of O18 had severely deficient, deficient or inadequate vitamin D concentrations. Adequate (8%) and optimal (8%) concentrations of vitamin D were observed in O18. All U18 and 75% of O18 had adequate ferritin concentrations. Potential toxicity (17%) and deficient (8%) ferritin concentrations were observed in O18. Vitamin D intake should be increased and multiple measures obtained throughout the season. More research is required on the variation of micronutrient status

Good nutrition is essential for the physical development of adolescent athletes, however data on dietary intakes of adolescent rugby players are lacking. This study quantified and evaluated dietary intake in 87 elite male English academy rugby league (RL) and rugby union (RU) players by age (under-16 (U16) and under-19 (U19) years old) and code (RL and RU). Relationships of intakes with body mass and composition (sum of 8 skinfolds) were also investigated. Using 4-day diet and physical activity diaries, dietary intake was compared to adolescent sports nutrition recommendations and the UK national food guide. Dietary intake did not differ by code, whereas U19s consumed greater energy (3366 ± 658 vs. 2995 ± 774 kcal.day-1), protein (207 ± 49 vs. 150 ± 53 g.day-1) and fluid (4221 ± 1323 vs. 3137 ± 1015 ml.day-1) than U16s. U19s consumed a better quality diet than U16s (greater intakes of fruit and vegetables; 4.4 ± 1.9 vs. 2.8 ± 1.5 servings.day-1; non-dairy proteins; 3.9 ± 1.1 vs. 2.9 ± 1.1 servings.day-1) and less fats and sugars (2.0 ± 1. vs. 93.6 ± 2.1 servings.day-1). Protein intake vs. body mass was moderate (r = 0.46, p < 0.001), and other relationships were weak. The findings of this study suggest adolescent rugby players consume adequate dietary intakes in relation to current guidelines for energy, macronutrient and fluid intake. Players should improve the quality of their diet by replacing intakes from the fats and sugars food group with healthier choices, while maintaining current energy, and macronutrient intakes.

It has previously been thought that reductions in inspired partial pressure of oxygen (PiO2) as a result of either reduced barometric pressure (PB) or inspired fraction of oxygen (FiO2) (normobaric hypoxia (NH)) would produce the same physiological responses. However, recent studies have reported differences between terrestrial altitude (TA) and NH. This may lead to differences in substrate utilisation during exercise; however, this is yet to be evaluated. The purpose was to compare whole-body substrate oxidation during s82 Day 2. Posters – Physiology and Nutrition Downloaded by exercise following co-ingestion of glucose and fructose on acute exposure to TA and NH. With institutional and Ministry of Defence ethical approval, eight male military personnel (age; 26.75 ± 4.86 years) completed a maximal oxygen uptake test and two experimental trials. These consisted of 2-hour cycling (~55%Wmax) at TA (3375 m; PiO2 ~ 96 mmHg) in the Italian Alps (Torino Hut) and in NH at an equivalent altitude (FiO2 ~ 13.8%, PiO2 ~ 96 mmHg). Carbohydrate (CHO) formulations (1.2 g · min-1 glucose and 0.6 g · min-1 fructose) were ingested immediately prior to and every 15 min throughout exercise. Whole-body substrate oxidation was measured using indirect calorimetry. Blood samples were drawn regularly for assessment of glucose, lactate, insulin and free fatty acids (FFA). Total energy expenditure was similar (P = 0.83; d = 0.03) in TA and NH (1285 ± 142 kcal and 1277 ± 98 kcal). Mean CHO oxidation during exercise was higher in NH (1.99 ± 0.25 g · min-1) compared to TA (1.20 ± 0.05 g · min-1), though not significant (P = 0.06; d = 0.91). The relative contribution ofCHO to the total energy yield was higher inNH compared to TA (69.82 ± 25.73% and 41.89 ± 22.57%), though not significant (P = 0.06; d = 0.50). Mean fat oxidation was higher at TA (0.72 ± 0.03 g · min-1) compared to NH (0.36 ± 0.07 g · min-1), though not significant (P = 0.06; d = 0.96). FFA concentrations were higher at TA compared to NH (P=0.003; d = 0.69), withTAproducing lower insulin concentrations than NH (P = 0.003; d = 0.46).There were no significant differences between the conditions for glucose (P = 0.06; d = 0.15) and lactate (P = 0.06; d = 0.19) concentrations. This study showed no significant difference in total energy expenditure at NH and TA. There was however evidence that the proportional part of CHO oxidation was increased during NH whilst the proportional part of fat oxidation was increased at TA. These differences just failed to reach statistical significance at the 5% level. Further investigation regarding substrate utilisation in reduced PB compared to FiO2 is warranted.

The hydration status of rugby league players during competitive home match play was assessed throughout the 2008 Super League season. Fourteen players from 2 Super League clubs were monitored (72 observations). On arrival, 2 h prior to kick off, following normal prematch routines, players' body mass were measured following a urine void. Prematch fluid intake, urine output, and osmolality were assessed until kick off, with additional measurements at half time. Fluid intake was also monitored during match play for club B only, and final measurements of variables were made at the end of the match. Mean body mass loss per match was 1.28 ± 0.7 kg (club A, 1.15 kg; club B, 1.40 kg), which would equate to an average level of dehydration of 1.31% (mass loss, assumed to be water loss, expressed as a percentage of body mass), with considerable intra-individual coefficient of variation (CV, 47%). Mean fluid intake for club B was 0.64 ± 0.5 L during match play, while fluid loss was 2.0 ± 0.7 L, with considerable intra-individual CV (51% and 34%, respectively). Mean urine osmolality was 396 ± 252 mosm·kg-1 on arrival, 237 ± 177 mosm·kg-1 prematch, 315 ± 133 mosm·kg-1 at half time, and 489 ± 150 mosm·kg-1 postmatch. Body mass losses were primarily a consequence of body fluid losses not being completely balanced by fluid intake. Furthermore, these data show that there is large inter- and intra-individual variability of hydration across matches, highlighting the need for future assessment of individual relevance.

This study aimed to establish whether a series of 3 apneas before a 400-m freestyle time-trial affected swimming performance when compared with and combined with a warm-up. Nine (6 males and 3 females) regional to national standard swimmers completed four 400-m freestyle time-trials in 4 randomized conditions: without warm-up or apneas (CON), warm-up only (WU), apneas only (AP), and warm-up and apneas (WUAP). Time-trial performance was significantly improved after WUAP (275.79 ± 12.88 seconds) compared with CON (278.66 ± 13.31 seconds, p = 0.035) and AP (278.64 ± 4.10 seconds, p = 0.015). However, there were no significant differences between the WU (276.01 ± 13.52 seconds, p > 0.05) and other interventions. Spleen volume compared with baseline was significantly reduced after the apneas by a maximum of ∼45% in the WUAP and by ∼20% in WU. This study showed that the combination of a warm-up with apneas could significantly improve 400-m freestyle swim performance compared with a control and apnea intervention. Further investigation into whether long-term apnea training can enhance this response is justified.

Background: A better understanding of hypoxia-induced changes in substrate utilisation can facilitate the development of nutritional strategies for mountaineers, military personnel and athletes during exposure to altitude. However, reported metabolic responses are currently divergent. As such, this systematic review and meta-analysis aims to determine the changes in substrate utilisation during exercise in hypoxia compared with normoxia and identify study characteristics responsible for the heterogeneity in findings. Methods: A total of six databases (PubMed, the Cochrane Library, MEDLINE, SPORTDiscus, PsychINFO, and CINAHL via EBSCOhost) were searched for published original studies, conference proceedings, abstracts, dissertations and theses. Studies were included if they evaluated respiratory exchange ratio (RER) and/or carbohydrate or fat oxidation during steady state exercise matched for relative intensities in normoxia and hypoxia (normobaric or hypobaric). A random-effects meta-analysis was performed on outcome variables. Meta-regression analysis was performed to investigate potential sources of heterogeneity. Results: In total, 18 studies were included in the meta-analysis. There was no significant change in RER during exercise matched for relative exercise intensities in hypoxia, compared with normoxia (mean difference: 0.01, 95% CI: -0.02 to 0.05; n = 31, p = 0.45). Meta-regression analysis suggests that consumption of a pre-exercise meal (p < 0.01) and a higher exercise intensity (p = 0.04) when exposed to hypoxia may increase carbohydrate oxidation compared with normoxia. Conclusions: Exposure to hypoxia did not induce a consistent change in the relative contribution of carbohydrate or fat to the total energy yield during exercise matched for relative intensities, compared with normoxia. The direction of these responses appears to be mediated by the consumption of a pre-exercise meal and exercise intensity. Key words: Altitude, exercise, substrate, carbohydrate, fat, oxidation, systematic review

The ergogenic benefits of carbohydrate (CHO) ingestion in cycling and running have been widely reported. Studies directly comparing the effect of CHO ingestion on CHO oxidation rates in cycling and running suggest no difference in exogenous CHO oxidation between these exercise modes. Potential differences in endogenous fuel use between cycling and running when ingesting CHO may lead to a greater benefit in cycling rather than running time trial (TT) performance. Direct comparisons of the effect of CHO ingestion during endurance exercise on subsequent cycling or running TT performance are limited. This study tested the hypothesis that ingesting CHO during 120 min of constant intensity exercise would benefit subsequent TT performance more in cycling than running. Methods: In a randomised, placebo controlled, double blind crossover trial, 10 male triathletes (VO2 max cycle 51.65±5.53, run 59.07±6.14 mL kg min ) completed 4 separate exercise trials. Each trial consisted of cycling or running at 70% of mode specific VO2max for 120min whilst ingesting either a CHO drink (2:1 glucose: fructose, 90g h ) or an equal volume of taste matched 0% CHO placebo (PLA) (750mL h ). After 10min recovery, participants completed a TT in the same mode of exercise, running 6km or cycling 16km. The CHO drink was enriched with uniformly labelled C glucose and C fructose isotopes to quantify exogenous and endogenous CHO oxidation. Due to limitations of the tracer methods used in the first hour, only data for the final 60min of exercise are presented. Total CHO and fat oxidation rates were calculated from expired air using stoichiometric equations. Data were analysed using ANOVA, values are means±SD. Results: From 60 120 min of exercise mean fat oxidation rates did not differ between exercise modes (PLA cycle 0.52±0.17, run 0.56±0.22g min p=0.86; CHO cycle 0.37±0.12 run 0.40±0.17g min , p=0.82). CHO ingestion reduced fat oxidation within cycling (p<0.01) and running trials (p=0.02) compared to PLA. Mean total CHO oxidation rates did not differ between trials (PLA cycle 2.52±0.74, run 2.21±0.46g min , p=0.23, CHO cycle 2.95±0.40, run 2.77±0.55g min , p=0.47). Mean exogenous CHO oxidation did not differ with CHO ingestion (cycle 0.87±0.22 run 0.75±0.31g min , p=0.31). CHO ingestion reduced endogenous CHO oxidation in cycling (PLA 2.52±0.74, CHO 2.10±0.41g min , p=0.03) but not running (PLA 2.21±0.46, CHO 2.00±0.61g min , p=0.44). TT performance improved 10% in cycling and 3% in running after CHO ingestion (p<0.01). TT performance improvement was greater in cycling than running (p=0.04, ES=1.45). Conclusions: This study demonstrates a greater improvement in cycling versus running TT performance after CHO ingestion. This may relate to the greater sparing of endogenous CHO in cycling versus running during the previous exercise period when CHO is ingested.

The Vendée Globe is a solo round-the-world sailing race without stopovers or assistance, a physically demanding challenge for which appropriate nutrition should maintain energy balance and ensure optimum performance. This is an account of prerace nutritional preparation with a professional and experienced female racer and assessment of daily nutritional intake (NI) during the race using a multimethod approach. A daily energy intake (EI) of 15.1 MJ/day was recommended for the race and negotiated down by the racer to 12.7 MJ/day, with carbohydrate and fluid intake goals of 480 g/day and 3,020 ml/day, respectively. Throughout the 99-day voyage, daily NI was recorded using electronic food diaries and inventories piloted during training races. NI was assessed and a postrace interview and questionnaire were used to evaluate the intervention. Fat mass (FM) and fat-free mass (FFM) were assessed pre- (37 days) and postrace (11 days) using dual-energy X-ray absorptiometry, and body mass was measured before the racer stepped on the yacht and immediately postrace. Mean EI was 9.2 MJ/day (2.4-14.3 MJ/day), representing a negative energy balance of 3.5 MJ/day under the negotiated EI goal, evidenced by a 7.9-kg loss of body mass (FM -7.5 kg, FFM -0.4 kg) during the voyage, with consequent underconsumption of carbohydrate by ~130 g/day. According to the postrace yacht food inventory, self-reported EI was underreported by 7%. This intervention demonstrates the practicality of the NI approach and assessment, but the racer's nutrition strategy can be further improved to facilitate meeting more optimal NI goals for performance and health. It also shows that evaluation of NI is possible in this environment over prolonged periods, which can provide important information for optimizing nutritional strategies for ocean racing.

Criterion data for total energy expenditure (TEE) in elite rugby are lacking, which prediction equations may not reflect accurately. This study quantified TEE of 27 elite male rugby league (RL) and rugby union (RU) players (U16, U20, U24 age groups) during a 14-day in-season period using doubly labelled water (DLW). Measured TEE was also compared to estimated, using prediction equations. Resting metabolic rate (RMR) was measured using indirect calorimetry, and physical activity level (PAL) estimated (TEE:RMR). Differences in measured TEE were unclear by code and age (RL, 4369 ± 979; RU, 4365 ± 1122; U16, 4010 ± 744; U20, 4414 ± 688; U24, 4761 ± 1523 Kcal.day-1). Differences in PAL (overall mean 2.0 ± 0.4) were unclear. Very likely differences were observed in RMR by code (RL, 2366 ± 296; RU, 2123 ± 269 Kcal.day-1). Differences in relative RMR between U20 and U24 were very likely (U16, 27 ± 4; U20, 23 ± 3; U24, 26 ± 5 Kcal.kg-1.day-1). Differences were observed between measured and estimated TEE, using Schofield, Cunningham and Harris-Benedict equations for U16 (187 ± 614, unclear; -489 ± 564, likely and -90 ± 579, unclear Kcal.day-1), U20 (-449 ± 698, likely; -785 ± 650, very likely and -452 ± 684, likely Kcal.day-1) and U24 players (-428 ± 1292; -605 ± 1493 and -461 ± 1314 Kcal.day-1, all unclear). Rugby players have high TEE, which should be acknowledged. Large inter-player variability in TEE was observed demonstrating heterogeneity within groups, thus published equations may not appropriately estimate TEE.

Purpose: This study compared the co-ingestion of glucose and fructose on exogenous and endogenous substrate oxidation during prolonged exercise at terrestrial high altitude (HA) versus sea level, in women. Method: Five women completed two bouts of cycling at the same relative workload (55% Wmax) for 120 minutes on acute exposure to HA (3375m) and at sea level (~113m). In each trial, participants ingested 1.2 g.min-1 of glucose (enriched with 13C glucose) and 0.6 g.min-1 of fructose (enriched with 13C fructose) before and every 15 minutes during exercise. Indirect calorimetry and isotope ratio mass spectrometry were used to calculate fat oxidation, total and exogenous carbohydrate oxidation, plasma glucose oxidation and endogenous glucose oxidation derived from liver and muscle glycogen. Results: The rates and absolute contribution of exogenous carbohydrate oxidation was significantly lower at HA compared with sea level (ES>0.99, P<0.024), with the relative exogenous carbohydrate contribution approaching significance (32.6±6.1 vs. 36.0±6.1%, ES=0.56, P=0.059) during the second hour of exercise. In comparison, no significant differences were observed between HA and sea level for the relative and absolute contributions of liver glucose (3.2±1.2 vs. 3.1±0.8%, ES=0.09, P=0.635 and 5.1±1.8 vs. 5.4±1.7 grams, ES=0.19, P=0.217), and muscle glycogen (14.4±12.2% vs. 15.8±9.3%, ES=0.11, P=0.934 and 23.1±19.0 vs. 28.7±17.8 grams, ES=0.30, P=0.367). Furthermore, there was no significant difference in total fat oxidation between HA and sea level (66.3±21.4 vs. 59.6±7.7 grams, ES=0.32, P=0.557). Conclusion: In women, acute exposure to HA reduces the reliance on exogenous carbohydrate oxidation during cycling at the same relative exercise intensity.

This study compared the effects of co-ingesting glucose and fructose on exogenous and endogenous substrate oxidation during prolonged exercise at altitude and sea level, in men. Seven male British military personnel completed two bouts of cycling at the same relative workload (55% Wmax) for 120 minutes on acute exposure to altitude (3375m) and at sea level (~113m). In each trial, participants ingested 1.2 g.min-1 of glucose (enriched with 13C glucose) and 0.6 g.min-1 of fructose (enriched with 13C fructose) directly before and every 15 minutes during exercise. Indirect calorimetry and isotope ratio mass spectrometry were used to calculate fat oxidation, total and exogenous carbohydrate oxidation, plasma glucose oxidation and endogenous glucose oxidation derived from liver and muscle glycogen. Total carbohydrate oxidation during the exercise period was lower at altitude (157.7±56.3 grams) than sea level (286.5±56.2 grams, P=0.006, ES=2.28), whereas fat oxidation was higher at altitude (75.5±26.8 grams) than sea level (42.5±21.3 grams, P=0.024, ES=1.23). Peak exogenous carbohydrate oxidation was lower at altitude (1.13±0.2 g.min-1) than sea level (1.42±0.16 g.min-1, P=0.034, ES=1.33). There were no differences in rates, or absolute and relative contributions of plasma or liver glucose oxidation between conditions during the second hour of exercise. However, absolute and relative contributions of muscle glycogen during the second hour were lower at altitude (29.3±28.9 grams, 16.6±15.2%) than sea level (78.7±5.2 grams (P=0.008, ES=1.71), 37.7±13.0% (P=0.016, ES=1.45). Acute exposure to altitude reduces the reliance on muscle glycogen and increases fat oxidation during prolonged cycling in men, compared with sea level.

Due to the focus of research within athletic populations, little is known about the hydration strategies of rugby league referees. We observed all 8 full-time professional referees, during 31 Super League matches to investigate the drinking strategies and magnitude of dehydration (body mass loss) experienced by referees during match play. Referees arrived and remained euhydrated (urine osmolality; pre and post-match 558 ± 310 and 466 ± 283 mOsmol•kg-1). Mean body mass change was -0.7 ± 0.8%, fluid loss was 890 ± 435 g and fluid intake was 444 ± 167, 438 ± 190, 254 ± 108 and 471 ± 221 g during pre-match, first-half, half-time and second-half. This study suggests elite referees adopt appropriate hydration strategies during match-play to prevent large reductions in body mass, although individual variability was observed. Future research should investigate dehydration in referees from other sports and the effects on refereeing performance.