Dr Matthew Barlow

Purpose This study examined the magnitude of physiological strain imposed by repeated maximal static and dynamic apneas through assessing a panel of stress-related biomarkers. Methods Eleven healthy men performed on three separate occasions (≥72-h apart): a series of five repeated maximal (i) static (STA) or (ii) dynamic apneas (DYN) or (iii) a static eupneic protocol (CTL). Venous blood samples were drawn at 30, 90, and 180-min after each protocol to determine ischaemia modified albumin (IMA), neuron-specific enolase (NSE), myoglobin, and high sensitivity cardiac troponin T (hscTnT) concentrations. Results IMA was elevated after the apnoeic interventions (STA,+86%;DYN,+332%,p ≤ 0.047) but not CTL (p = 0.385). Myoglobin was higher than baseline (23.6 ± 3.9 ng/mL) 30-min post DYN (+70%,38.8 ± 13.3 ng/mL,p = 0.030). A greater myoglobin release was recorded in DYN compared with STA and CTL (p ≤ 0.035). No changes were observed in NSE (p = 0.207) or hscTnT (p = 0.274). Conclusions Five repeated maximal DYN led to a greater muscle injury compared with STA but neither elicited myocardial injury or neuronal-parenchymal damage.

Introduction: The purpose of the present study was to assess the effects of acute nitrate (NO3-)-rich beetroot juice supplementation on peripheral oxygen saturation (SpO2), heart rate (HR), and pulmonary gas exchange during submaximal static and dynamic apnoea. Methods: Nine (six male, three female) trained apneists (age: 39.6 ± 8.2 years, stature: 170.4 ± 11.5cm, body mass: 72.0 ± 11.5 kg) performed three submaximal static apnoeas at 60%, 70% and 80% of the participant’s current reported personal best time, followed by three submaximal (~ 75% or personal best distance) dynamic apnoeas following the consumption of either a 140 ml concentrated NO3--rich beetroot juice (BRJ; 7.7 mmol NO3-) or a NO3--depleted placebo (PLA; 0.1 mmol NO3-) in double-blind randomised manner. HR and SpO2 were measured via fingertip pulse oximetry at the nadir, and online gas analysis was used to assess pulmonary oxygen uptake (V̇O2) during recovery following breath-holds. Results: There were no differences (P <0.05) between conditions for HR (PLA = 59 ± 11 bpm and BRJ = 61 ± 12 bpm), SpO2 (PLA = 83 ± 14% and BRJ = 84 ± 9%) or V̇O2 (PLA = 1.00 ± 0.22 L.min-1 and BRJ = 0.97 ± 0.27 L.min-1). Conclusion: The consumption of 7.7mmol of beetroot juice supplementation prior to a series of submaximal static and dynamic apnoeas did not induce a significant change in SpO2, HR and V̇O2, when compared to placebo. Therefore there is no apparent physiological response that may benefit free-divers as a result of the supplementation.

The aim of this study was to evaluate the anthropometric profiles of male surfers and to investigate the relationship of these measures with performance and ability. Following institutional ethical approval, 79 male surfers underwent anthropometric assessment. These surfers composed of three sub-groups of professional (n=17; age: 34.12, s =3.81 years, stature: 177.28, s =6.29 cm; body mass: 78.57, s =7.17 kg), junior national level (n=15; age: 15.61, s =1.06 years, stature: 173.86, s =5.72 cm; body mass: 63.27, s =7.17 kg) and intermediate level surfers (n=47; age: 22.47, s =2.80 years, stature: 179.90, s =5.41; body mass: 77.83, s =9.43 kg). The mean somatotype values for the different groups of surfers were found to be 2.48, 5.00 and 1.03 for the professional surfers; 2.18, 3.72 and 3.24 for the junior national surfers and 2.79, 3.57 and 2.42 for the intermediate surfers. Professional surfers were significantly (P < 0.01) more mesomorphic and less ectomorphic than intermediate level surfers. Significant correlations were observed between endomorphy (r = −0.399, P < 0.01), sum of six skinfolds (r = −0.341, P < 0.05), and body fat percentage (r = −0.380, P < 0.01) and the rating of ability among the intermediate group of surfers. Across all participants, the rating of surfer ability was significantly correlated with endomorphy (r = −0.366, P≤0.01), mesomorphy (r = 0.442, P < 0.01), sum of six skinfolds (r = −0.274, P < 0.05) and body fat percentage (r = −0.268, P < 0.05). Findings suggest that the levels of adiposity and muscularity may influence the potential for progression between intermediate and professional-level surfing performance.

The aim of this study was to determine the contractile properties and muscle stiffness to assess lateral symmetry in competitive female surfers. Fifteen competitive female surfers volunteered to participate in the study. Tensiomyography was used to derive maximum muscle belly displacement, and time delay duration of the Biceps Brachiis, Biceps Femoris, Deltoid, Gastrocnemius lateral head, Rectus Femoris, Tibialis Anterior, Triceps Brachii and Vastus Medialis. No significant differences between right and left limbs at in any of the tested muscles were observed (p > 0.05). Competitive female surfers showed that upper body muscles had the ability to generate force rapidly during contractions, while the lower body muscles generated force at a slower rate. Surf specific training seems to have had an influence on the contractile properties, and stiffness of these muscles. The neuromuscular profile provided here provides further nor-mative data to this unique population.

Purpose. The objective of this study was to determine the relationships of peak oxygen uptake ( VÌO2peak), power at VÌO2peak and power at the anaerobic threshold (AT) with national ranking in a sample of British high performance junior surfers. Methods. Eighteen male surfers (aged 15.4 ± 1.4 years) from the British Junior Surfing team were tested for VÌO2peak and AT using an adapted kayak ergometer; national ranking was used to indicate performance level. The AT was identified as the point at which VÌE/VÌO2 started to rise without a concomitant increase in VÌE/VÌCO2. Spearman's rank (rs) and partial correlations (rp) controlling for age were used to identify the relationships between the physiological variables and national ranking. Results. Mean VÌO2peak was 3.1 ± 0.5 l · min

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Surfing is described as an intermittent exercise that comprises bouts of high intensity exercise interspersed with periods of low intensity activity and rest, utilising both the upper body during paddling and the lower body during surfing. The short-term supplementation of creatine has been reported to improve maximal power, strength and work performed during repetitive sprint performance (Williams et al., 1999: Creatine the power supplement. Leeds: Human Kinetics).This study assessed the effect of short-term(20 g day71 for 5 days) creatine supplementation on body composition, repeated upper body anaerobic power and competition performance in club level surfers. Following institutional ethical approval, seventeen club level male surfers (mean: age 23.06, s¼4.21 years, stature 79.68, s¼9.92 cm) underwent a randomised, double blind, placebo controlled, cross-over design study. Testing comprised assessmentof body mass and total body water using bioelectrical impedance analysis, a repeated upper body Wingate (5615 s) with active recovery (120 s) and passive recovery (105 s), based on time motion analysis of competitive surfing (Mendez-Villanueva et al., 2003: Journal of Science and Medicine in Sport, 23, 70–74). Competition performance was assessed by rank in competition and number of waves caught per heat. Participants were tested at baseline and randomly assigned to creatine and placebo groups, receiving 20 g day71 for 5 days of creatine monohydrate (CMH) or placebo (polyethylene glycol – PEG). Testing was repeated following supplementation. Participants then underwent a 4 week wash-out period before the groups were reversed and testing repeated. Table I shows an insignificant increase in body mass (0.32 kg) and total body water (0.59 kg) following 5 days of creatine loading. Oral creatine supplementation also had no significant effect on repeated upper body anaerobic peak power (22.00 W increase) and average power (10.37 W increase) supporting the findings of Green et al., (2001: Journal of Strength and Conditioning Research, 15, 36–41) using a similar study design with physically active men. There was no significant effect on competitive performance in terms of ranking or number of waves ridden. These results may be due to the acute effects of the variable surfing conditions during the study period on physiological condition of the participants affecting performance in all tests.

Surfing is a high intensity intermittent exercise which in recent years has experienced a rapid increase in participation rates and growing professionalism amongst competitive athletes. Studies in a variety of sports have indicated that, unless one has a distinctive and specific body form suitable to the sport, there is little likelihood of success in top class performance (Lowdon, 1980: Australian Journal of Sports Medicine 12, 34–39). The aim of this study was to investigate the relationship between anthropometric measures and national ranking in male high performance junior British surfers. Following institutional ethical approval and the completion of parental informed consent (children giving assent) high performance male surfers (N¼16, age¼mean 15.61, s¼1.06 years) participated in anthropometric measures of stature, body mass, skinfolds (Tricep, subscapular, biceps, iliac crest, supraspinale, abdominal, front thigh and medial calf), girths (arm flexed and tensed, waist, gluteal and calf) and breadths (humerus and femur). All measures were taken in accordance with the guidelines of the International Society for the Advancement of Kinanthropometry (ISAK). These were used to calculate body mass index, waist to hip ratio and body fat percentage using the equation of Yuhasz (1975: Physical fitness manual. London: University of Western Ontario). A correlation analysis was performed using SPSS for Windows (V.15) between the measured physiological variables and the numerical national ranking of the subjects. Significant (P50.05) correlations were found with Illiac Crest skinfold measurement r¼0.52 (R2¼0.27) and body fat percentage r¼0.60 (R2¼0.36). Thus the coefficient’s of determination for these measures suggest that the iliac crest skinfold measure can explain 27% of the variance in ranking and body fat percentage explains 36% of the variance within the sample used. No other significant correlations were found. The results suggest that within this age group body fatness may be conducive to surfing performance. This is supported by Felder et al (1998: International Journal of Sport Nutrition, 8(1), 36–48) and Lowdon (1980: Australian Journal of Sports Medicine 12,34–39) who theorised that increased body fat may well protect the surfer from the cold and wet environment in which they perform.

This study investigated the effects of wave conditions on performance and the physiological responses of surfers. After institutional ethical approval 39 recreational surfers participated in 60 surfing sessions where performance and physiological response were measured using global positioning system (GPS) heart rate monitors. Using GPS, the percentage time spent in surfing activity categories was on average 41.6, 47.0, 8.1, and 3.1% for waiting, paddling, riding, and miscellaneous activities, respectively. Ability level of the surfers, wave size, and wave period are significantly associated with the physiological, ride, and performance parameters during surfing. As the ability level of the surfers increases there is a reduction in the relative exercise intensity (e.g., average heart rate as a percentage of laboratory maximum, rpartial = -0.412, p < 0.01) which is in contrast to increases in performance parameters (e.g., maximum ride speed (0.454, p < 0.01). As the wave size increased there were reductions in physiological demand (e.g., total energy expenditure rpartial = -0.351, p ≤ 0.05) but increases in ride speed and distance measures (e.g., the maximum ride speed, 0.454, p < 0.01). As the wave period increased there were increases in intensity (e.g., average heart rate as a percentage of laboratory maximum, rp = 0.490, p < 0.01) and increases in ride speed and distance measures (e.g., the maximum ride speed, rpartial = 0.371, p < 0.01). This original study is the first to show that wave parameters and surfer ability are significantly associated with the physiological response and performance characteristics of surfing.

This project aimed to investigate the effect of a 6-week repeated sprint in hypoxia (RSH) intervention in normobaric hypoxia (NH) on middle-distance performance and performance parameters in middle-distance athletes, and to establish the potential underpinning adaptation to performance enhancement through the use of near-infrared spectroscopy (NIRS). The novelty of this thesis was its aim of producing a protocol which was specific to middle-distance runners, produced with the help of Leeds Beckett Coaches, to replicate a typical track interval session to allow real-world application. 5 trained middle-distance athletes completed a 6-week (12 session) repeated sprint training intervention in hypoxia (3000m in week 1-3; 3750m in week 4-6) or normoxia (sea-level; 0m) (RSN), both completed in a NH chamber to blind the participants. Weekly sessions were comprised of a low-intensity session (6 sets; 6 reps at 90% of 800m pace) and a high intensity session (5 sets: 4 reps at 120% of 800m pace), with intervals of 15-seconds interspersed by 30-seconds passive recovery. Performance outcomes were measured using an 800m time-trial, submaximal and time to exhaustion test (TTE). With underpinning adaptations measured using carbon monoxide (CO) rebreathing to determine haemoglobin mass (Hbmass) and changes in muscle oxygenation measured using NIRS. No overall improvement was found in 800m time-trial performance following RSN (pre: 148.6 ± 16.84 vs. post: 148.6 ± 13.40 seconds), however, participant 6 of the hypoxia group (HYP) showed the greatest overall improvement of 6 seconds. Whereas, following RSN there was an overall reduction in 800m time-trial performance (+1.3 seconds). Aerobic capacity (V̇O2max) and V̇O2 onset kinetics were reduced following RSH and RSN, while mean reaction time (MRT) was improved in HYP (—21.24 seconds; d=2.6, p=0.08). Muscle oxygen saturation (SmO2) was improved following RSH in participant 6 (-2.01 ± 5.25 vs. 6.99 ± 1.35 %). Total haemoglobin (tHb) was increased (19.07 ± 2.67 μM) following the intervention in participant 2 (NOR), and participant 3 increased slightly (1.94 ± 9.88 μM), however, there was no overall trend found for the hypoxic group. Although the findings of this study were inconsistent and showed no overall change, individual improvements suggest that with a greater sample size and greater control on external training to reduce confounding factors, RSH could be a beneficial intervention for improving middle-distance performance through improvements in peripheral adaptations to muscle oxygenation.

Purpose This study examined the influence of dynamic apnoea training on splenic volume and haematological responses in non-breath-hold divers (BHD). Methods Eight non-BHD performed ten maximal dynamic apnoeas, four times a week for six weeks. Splenic volumes were assessed ultrasonically, and blood samples were drawn for full blood count analysis, erythropoietin, iron, ferritin, albumin, protein and osmolality at baseline, 24 h post the completion of each week’s training sessions and seven days post the completion of the training programme. Additionally, blood samples were drawn for haematology at 30, 90, and 180 min post session one, twelve and twenty-four. Results Erythropoietin was only higher than baseline (6.62 ± 3.03 mlU/mL) post session one, at 90 (9.20 ± 1.88 mlU/mL, p = 0.048) and 180 min (9.04 ± 2.35 mlU/mL, p = 0.046). Iron increased from baseline (18 ± 3 µmol/L) post week five (23 ± 2 µmol/L, p = 0.033) and six (21 ± 6 µmol/L; p = 0.041), whereas ferritin was observed to be lower than baseline (111 ± 82 µg/L) post week five (95 ± 75 µg/L; p = 0.016), six (84 ± 74 µg/L; p = 0.012) and one week post-training (81 ± 63 µg/L; p = 0.008). Reticulocytes increased from baseline (57 ± 12 × 109/L) post week one (72 ± 17 × 109/L, p = 0.037) and six (71 ± 17 × 109/L, p = 0.021) while no changes were recorded in erythrocytes (p = 0.336), haemoglobin (p = 0.124) and splenic volumes (p = 0.357). Conclusions Six weeks of dynamic apnoeic training increase reticulocytes without altering mature erythrocyte concentration and splenic volume.

Purpose This study aimed to determine whether a series of repeated maximal voluntary apnoeas is effective in improving subsequent time trial performance in competitive level track and field athletes. Methods Seventeen competitive runners volunteered for this study and based on their preferred competitive distance they were placed either in the 200 m (5 male, 4 female) or 1000 m group (3 male, 5 female). On two separate occasions (≤ 7 days apart), the participants performed a running time-trial that was preceded either by: (i) a standardised warm up (WO) or (ii) a standardised warm up succeeded by five repeated maximal dry static apnoeas (WA). Splenic volume, haematology and cardiovascular parameters were monitor at rest, before and after each time-trial. Results WA resulted in a significantly faster performance (27.51 ± 3.49 s; P = 0.009) compared with WO (27.96 ± 3.34 s) in the 200 m group, whereas no differences were observed in the 1000 m group (WA, 211.10 ± 26.18 s; WO, 215.82 ± 25.13 s, P = 0.120). No differences were noted in splenic volume between WO and WA in either group (P ≥ 0.081). Haemoglobin was significantly elevated after breath-holding in the 200 m (+ 7 g/dL, P = 0.041) but not 1000 m group. Conclusion This study demonstrates that five repeated maximal apnoeas are capable of significantly improving a 200 m but not a 1000 m time-trial performance in competitive track and field athletes.

Abstract

Introduction Heat adaptation is protective against heat illness however its role in heat syncope, due to reflex mechanisms, has not been conclusively established. The aim of this study was to evaluate if heat acclimation (HA) was protective against heat syncope and to ascertain underlying physiological mechanisms. Method 20 (15 males, 5 females) endurance trained cyclists were randomised to either 8 days of mixed active and passive HA (HEAT) or temperate exercise (CONTROL). Prior to, and following, the interventions participants underwent a head up tilt (HUT) with graded lower body negative pressure (LBNP) continued until presyncope with measurement of cardiovascular parameters. Heat stress testing was performed to determine physiological and perceptual measures of HA. Results There was a significant increase in orthostatic tolerance (OT), as measured by HUT/LBNP, in the HEAT group (pre-intervention; 28 ± 9 mins, post-intervention; 40 ± 7 mins) compared to CONTROL (pre-intervention; 30 ± 8 mins, post-intervention; 33 ± 5 mins) (p = 0.0116). Heat acclimation resulted in a significantly reduced peak and mean rectal and skin temperature (p < 0.0141), peak heat rate (p < 0.0033), thermal comfort (p < 0.0411) and rating of perceived exertion (p < 0.0251). There was a significantly increased plasma volume (PV) in the HEAT group in comparison to CONTROL (p = 0.0293). Discussion Heat adaptation causes improvements in OT and is likely to be beneficial in patients with heat exacerbated reflex syncope. Heat acclimation mediated PV expansion is the likely predominant physiological mechanism underlying improved OT.

Purpose: To evaluate the anthropometric profiles of female surfers and to identify whether any anthropometrical factors might predict competitive ranking. Secondly to evaluate the activity profile of female competitive surfing with respect to environmental conditions using GPS derived measures. Methods: Following institutional ethical approval n = 31 female competitive surfers underwent anthropometric assessment (mean age: 20.49, s = 5.32 years, stature: 165.2, s = 4.8 cm; body mass: 63.0, s = 6.8 Kg) a subsample (n = 22) wore GPS units during competition at four different locations with varied surfing conditions. Results: The mean somatotype values the surfers was found to be (Endo-Meso-Ecto) 4.06 – 4.15 – 2.01. Significant correlations (p <0.05) were found between National ranking and triceps, medial calf skinfolds, sum of six skinfolds, body fat percentage and sum of eight skinfolds. Percentage time sitting, paddling and riding were 62.58% ± 10.18%, 30.70% ± 9.44% and 6.73% ± 2.91% respectively. The mean ride time, maximum ride time, total time spent riding and the total distance surfing were significantly correlated with the round of the competition. Furthermore, the number of rides, time spent riding, percentage of total distance surfing and percentage time riding were correlated with heat placement (p < 0.05). Time spent sitting was associated with poorer heat placements (p < 0.01). Conclusions: Body fat levels are associated with national ranking in competitive female surfers. The number of waves ridden in a heat, the length of the rides and activity levels were significantly related to heat placement and competition progression. Keywords: Body composition; sports; somatotypes; athletic performance/physiology; Muscle, skeletal; body size; body mass index; GPS; wave conditions; competition.

Introduction: There is evidence that intermittent hypoxic exposure (IHE) may improve high altitude (HA) performance. In this study, the effects of short-term IHE through voluntary apnea training on HA-related symptoms, including acute mountain sickness (AMS), were examined for the first time. Methods: Forty healthy adults were randomized to a self-administered apnea training (n = 19) or control (n = 21 no apnea training) group before ascent to an altitude of 5100 m in the Himalayas over 14 days. The apnea training was conducted at sea level (SL) and consisted of five breath holds per day in week 1, seven in week 2, followed by 10 per day from weeks 3 to 6 and until HA exposure. Saturation of arterial oxygen (SpO2), heart rate, sleep quality (Insomnia Severity Index [ISI]), rating of perceived exertion (RPE), blood pressure, and Lake Louise scores were measured at SL (in the United Kingdom) and at HA at 1400, 2700, 3400–3700, 4050–4200, 4800, and 5100–5200 m. Anxiety (Generalized Anxiety Disorder-7 [GAD-7]) scores were examined at SL, 1400, and 5100–5200 m. Results: Apnea training led to a significant increase in the mean longest breath-hold times from baseline (80.42 ± 32.49 [median 87.00] seconds) to the end of week 6 (107.02 ± 43.65 [113.00] seconds), respectively (p = 0.009). There was no significant difference in the prevalence of AMS (8/19 = 42.1% vs. 11/21 = 52.4%; RR 0.80; 95% confidence interval 0.41–1.57: p = 0.80) or in GAD-7, ISI and RPE, SpO2, heart rate, or blood pressure among the apnea versus control groups, respectively, at HA. Conclusions: Apnea training does not lessen HA-related symptoms in healthy adults traveling up to 5200 m. Larger studies using more challenging apnea protocols and at higher altitudes should be considered.

PURPOSE: The aim was to investigate the effect of dietary nitrate supplementation (in the form of beetroot juice, BRJ) for 20 days on salivary nitrite (a potential precursor of bioactive nitric oxide), exercise performance and high altitude (HA) acclimatisation in field conditions (hypobaric hypoxia). METHODS: This was a single-blinded randomised control study of 22 healthy adult participants (12 men, 10 women, mean age 28 ± 12 years) across a HA military expedition. Participants were randomised pre-ascent to receive two 70 ml dose per day of either BRJ (~12.5 mmol nitrate per day; n = 11) or non-nitrate calorie matched control (n = 11). Participants ingested supplement doses daily, beginning 3 days prior to departure and continued until the highest sleeping altitude (4800 m) reached on day 17 of the expedition. Data were collected at baseline (44 m altitude), at 2350 m (day 9), 3400 m (day 12) and 4800 m (day 17). RESULTS: BRJ enhanced the salivary levels of nitrite (p = 0.007). There was a significant decrease in peripheral oxygen saturation and there were increases in heart rate, diastolic blood pressure, and rating of perceived exertion with increasing altitude (p=<0.001). Harvard Step Test fitness scores significantly declined at 4800 m in the control group (p = 0.003) compared with baseline. In contrast, there was no decline in fitness scores at 4800 m compared with baseline (p = 0.26) in the BRJ group. Heart rate recovery speed following exercise at 4800 m was significantly prolonged in the control group (p=<0.01) but was unchanged in the BRJ group (p = 0.61). BRJ did not affect the burden of HA illness (p = 1.00). CONCLUSIONS: BRJ increases salivary nitrite levels and ameliorates the decline in fitness at altitude but does not affect the occurrence of HA illness.

Establishing normative ranges for Bone Mineral Density in female team sport athletes Purpose: It is common that female athlete cohorts generally have higher bone density compared to non-athletic controls or typical reference populations. However, activity specific reference databases are required to identify athletes who have comparatively low BMD within their sport, as this may highlight increased risk of stress fractures or occurrences of low energy availability. Method: A secondary data analysis of three female team sport cohorts (cricket, rugby league, netball, n=103) will be completed from previous dual x-ray absorptiometry scans (Lunar iDXA, GE Medical Systems). Bone mineral density (total, lumbar spine [L1-L4], total hip and neck of femur) will be analysed alongside age, mass, stature, and fat free lean mass. Results: Data is yet to be analysed. Conclusion: Sport specific ranges will inform improved practice to enable early identification of athletes at present risk or stress fracture or low energy availability outcomes as well as future risk of osteoporosis or fracture with ageing.

The skeleton of an elite cricket fast bowler is exposed to substantial ground reaction forces that are delivered through the front foot during the contact phase. There is also significant loading to the lumbo-pelvic region, through peak transverse plane rotation moments and increased anterior posterior shear forces. Non-contact bone injuries are common amongst fast bowlers, but few studies have investigated unilateral bone strength in this sports population. The aim of this study was to investigate cross-sectional geometry of the left and right proximal femur in elite fast bowlers to determine if any asymmetries or insufficiencies exist. Dual energy X-ray absorptiometry (GE Lunar iDXA) of the left and right proximal femur was performed in 16 elite male fast bowlers (age: 21.4 ±4.4 yrs; BMI: 24.7 ± 2.2 kg.m-2) and 12 normally-active controls (age: 21.4 (1.6) yrs; BMI: 23.7 ± 2.6 kg.m-2). Total body DXA determined lean tissue mass (LTM). The hip structural analysis programme (enCORE v15.0) determined areal bone mineral density (BMD), cross-sectional area (CSA), section modulus (Z), and cross-sectional moment of inertia (CSMI) of the femoral neck (Beck et al., 2007). Precision of outcomes ranges between 0.5 and 4.5% (Hind et al., 2012). Femoral neck and total hip aBMD were greater in fast bowlers than controls (p<0.001). All bone geometrical properties except for CSMI, were superior in fast bowlers compared to controls (p<0.05) before and after adjustment for height. LTM was associated with CSA (r = 0.725, p = 0.012), CSMI (r = 0.643, p = 0.033), Z (r = 0.728, p = 0.011) and BMD at the femoral neck (r = 0.647, p = 0.032). There were no associations with age. There were no asymmetries in bone strength when considering leg dominance (front foot) of the fast bowlers (p=0.103 to 0.784). Elite male fast bowlers have superior bone strength of the proximal femur with results inferring an enhanced resistance to axial (CSA), bending (Z) and compressive loads (BSI). This is likely to reflect a positive adaptation of bone to loading through fast bowling and greater LTM. No asymmetries in proximal femur bone properties were identified. Research is now required to explore bone strength properties of the spine and also in women fast bowlers, in relation to lumbo-pelvic injury.

Introduction: Cricket fast bowlers are at a higher risk of serious lumbar injuries compared to players of other positions and it is thought that loading to this region plays a part. Fast bowling exposes the lumbar spine to substantial bending, flexion and rotational forces as well as attenuated force transmission through the lower limb at front foot contact. Profiling lumbar spine bone properties in elite cricket fast bowlers may help us understand skeletal adaptation to this unique and complex loading. The aim of this study was to evaluate lumbar spine bone mass in elite male fast bowlers compared to cricketers of other positions using central dual- energy X-ray absorptiometry (DXA) with novel custom analysis of bilateral regions. Methods: Twenty-six elite male fast bowlers (age: 22.1 (5.8) yrs, BMI: 24.7 (1.8) kg.m-2) and 19 other elite male cricketers (comprising batsmen (10), spin bowlers (5) and wicket keepers (4); age: 19.2 (4.4) yrs, BMI: 23.2 (2.8) kg.m-2) received an anterior-posterior L1-L4 lumbar spine DXA (GE Lunar iDXA) scan. Bone mineral density (BMD), bone mineral content (BMC), bone width (BW), bone height (BH) and bone area (BA) were derived for each vertebrae. Bilateral analysis was computed for each individual vertebrae (L1-L4) using the custom facility, with region of interest boxes manually placed either side of the spinous process and utilisation of bone edge detection for the outer lumbar body (Lunar enCORE v 15.0). Results: L1-L4 BMD and BMC were significantly greater in fast bowlers than in other cricketers (1.464 (0.117) vs. 1.327 (0.133) g.cm-2, η2 = 0.238; 99.0 (14.2) vs. 87.5 (17.6) g, η2= 0.121; both p<0.001). BW was moderately greater in fast bowlers (4.67 (0.3) vs. 4.49 (0.4), p=0.08, η2= 0.07). There were no differences between groups in BA or BH, and there were no associations with age or BMI (p>0.05). Fast bowlers had significantly greater differences in bilateral L1-L4 BMD (p=0.021 - 0.036, η2 = 0.06 - 0.12). Corresponding with the dominant limb (front foot), differences in bilateral lumbar BMD ranged from 2.6% to 6.3%. Sub-group analyses of the fast bowlers by age found that in senior players (n=11), bilateral BMD differences were almost double those observed in U20's (n=15) at L1 - L3, but not at L4. Conclusions: Fast bowlers have superior lumbar spine BMD compared to cricketers in other positions. Fast bowlers also have larger differences in bilateral lumbar spine BMD, potentially reflecting the impact of side-specific loading generated during play. Bilateral adaptation of bone in L1-L3 may occur in response to loading over time but longitudinal study is needed. The lack of difference at L4 between seniors and U20's requires further investigation.

Nitrate supplementation appears to be most ergogenic when oxygen availability is restricted and subsequently may be particularly beneficial for swimming performance due to the breath-hold element of this sport. This represents the first investigation of nitrate supplementation and swimming time-trial (TT) performance. In a randomised double-blind repeated-measures crossover study, ten (5male, 5female) trained swimmers ingested 140ml nitrate-rich (~12.5mmol nitrate) or nitrate-depleted (~0.01mmol nitrate) beetroot juice. Three hours later, subjects completed a maximal effort swim TT comprising 168m (8 x 21m lengths) backstroke. Pre-exercise fractional exhaled nitric oxide concentration was significantly elevated with nitrate compared to placebo (17±9 vs. 7±3p.p.b., p=0.008). Nitrate supplementation had a likely trivial effect on overall swim TT performance (mean difference 1.22s; 90% CI -0.18– 2.6s; 0.93%; p=0.144; d=0.13; unlikely beneficial (22.6%), likely trivial (77.2%), most unlikely negative (0.2%)). The effects of nitrate supplementation during the first half of the TT were trivial (mean difference 0.29s; 90% CI -0.94–1.5s; 0.46%; p=0.678; d=0.05), but there was a possible beneficial effect of nitrate supplementation during the second half of the TT (mean difference 0.93s; 90% CI 0.13–1.70s; 1.36%; p=0.062; d=0.24; possibly beneficial (63.5%), possibly trivial (36.3%), most unlikely negative (0.2%)). The duration and speed of underwater swimming within the performance did not differ between nitrate and placebo (both p>0.30). Nitrate supplementation increased nitric oxide bioavailability but did not benefit short-distance swimming performance or the underwater phases of the TT. Further investigation into the effects of nitrate supplementation during the second half of performance tests may be warranted.

Purpose-This study sought to explore, for the first time, the effects of repeated maximal static and dynamic apnoeic attempts on the physiological milieu by assessing cerebral, cardiac and striatal muscle stress-related biomarkers in a group of elite breath-hold divers (EBHD). Methods-Sixteen healthy males were recruited (EBHD=8; controls=8). On two separate occasions EBHD performed two sets of five repeated maximal static apnoeas (STA) or five repeated maximal dynamic apnoeas (DYN). Controls performed a static eupnoeic protocol to negate any effects of water immersion and diurnal variation on haematology (CTL). Venous blood samples were drawn at 30, 90, and 180-mins after each protocol to determine S100β, neuron-specific enolase (NSE), myoglobin and high sensitivity cardiac troponin T (hscTNT) concentrations. Results-S100β and myoglobin concentrations were elevated following both apnoeic interventions (p<0.001; p≤0.028, respectively) but not after CTL (p≥0.348). S100β increased from baseline (0.024±0.005µg/L) at 30 (STA, +149%, p<0.001; DYN, +166%, p<0.001) and 90 mins (STA, +129%, p<0.001; DYN, +132%, p=0.008) following the last apnoeic repetition. Myoglobin was higher than baseline (22.3±2.7ng/mL) at 30 (+42%, p=0.04), 90 (+64%, p<0.001) and 180 mins (+49%, p=0.013) post-STA and at 90 mins (+63%, p=0.016) post-DYN. Post-apnoeic S100β and myoglobin concentrations were higher than CTL (STA, p<0.001; DYN, p≤0.004). NSE and hscTNT did not change from basal concentrations after the apnoeic (p≥0.146) nor following the eupnoeic (p≥0.553) intervention. from basal concentrations after the apnoeic (p≥0.146) nor following the eupnoeic (p≥0.553) intervention. Conclusions-This study suggests that a series of repeated maximal static and dynamic apnoeas transiently disrupt the blood-brain barrier and instigate muscle injury but do not induce neuronal-parenchymal damage or myocardial damage.

Splenic contractions occur in response to apnoea‐induced hypoxia with and without facial water immersion. However, the splenic responses to a series of static (STA) or dynamic (DYN) apnoeas with whole‐body water immersion in non‐divers (NDs) and elite breath‐hold divers (EBHDs) are unknown. EBHD (n = 8), ND (n = 10) and control participants (n = 8) were recruited. EBHD and ND performed a series of five maximal DYN or STA on separate occasions. Control performed a static eupnoeic (STE) protocol to control against any effects of water immersion and diurnal variation on splenic volume and haematology. Heart rate (HR) and peripheral oxygen saturation (SpO2) were monitored for 30 s after each apnoea. Pre‐ and post‐apnoeic splenic volumes were quantified ultrasonically, and blood samples were drawn for haematology. For EBHD and ND end‐apnoeic HR was higher (P < 0.001) and SpO2 was lower in DYN (P = 0.024) versus STA. EBHD attained lower end‐apnoeic SpO2 during DYN and STA than NDs (P < 0.001). Splenic contractions occurred following DYN (EBHD, −47 ± 6%; ND, −37 ± 4%; P < 0.001) and STA (EBHD, −26 ± 4%; ND, −26 ± 8%; P < 0.01). DYN‐associated splenic contractions were greater than STA in EBHD only (P = 0.042). Haemoglobin concentrations were higher following DYN only (EBHD, +5 ± 8g/L , +4 ± 2%; ND, +8 ± 3 g/L , +4.9 ± 3%; P = 0.019). Haematocrit remained unchanged after each protocol. There were no between group differences in post‐apnoeic splenic volume or haematology. In both groups, splenic contractions occurred in response to STA and DYN when combined with whole‐body immersion. DYN apnoeas, were effective at increasing haemoglobin concentrations but not STA apnoeas. Thus, the magnitude of the splenic response relates to the hypoxemic stress encountered during apnoeic epochs.

Purpose The aim of the study was to provide an evaluation of the oxygen transport, exchange and storage capacity of elite breath-hold divers (EBHD) compared with non-divers (ND). Methods Twenty-one healthy males’ (11 EBHD; 10 ND) resting splenic volumes were assessed by ultrasound and venous blood drawn for full blood count analysis. Percutaneous skeletal muscle biopsies were obtained from the m. vastus lateralis to measure capillarisation, and fibre type-specific localisation and distribution of myoglobin and mitochondrial content using quantitative immunofluorescence microscopy. Results Splenic volume was not different between groups. Reticulocytes, red blood cells and haemoglobin concentrations were higher (+ 24%, p < 0.05; + 9%, p < 0.05; + 3%, p < 0.05; respectively) and mean cell volume was lower (− 6.5%, p < 0.05) in the EBHD compared with ND. Haematocrit was not different between groups. Capillary density was greater (+ 19%; p < 0.05) in the EBHD. The diffusion distance (R95) was lower in type I versus type II fibres for both groups (EBHD, p < 0.01; ND, p < 0.001), with a lower R95 for type I fibres in the EBHD versus ND (− 13%, p < 0.05). Myoglobin content was higher in type I than type II fibres in EBHD (+ 27%; p < 0.01) and higher in the type I fibres of EBHD than ND (+ 27%; p < 0.05). No fibre type differences in myoglobin content were observed in ND. Mitochondrial content was higher in type I than type II fibres in EBHD (+ 35%; p < 0.05), with no fibre type differences in ND or between groups. Conclusions In conclusion, EBDH demonstrate enhanced oxygen storage in both blood and skeletal muscle and a more efficient oxygen exchange capacity between blood and skeletal muscle versus ND.

Serum erythropoietin (EPO) concentration is increased following static apnoea-induced hypoxia. However, the acute erythropoietic responses to a series of dynamic apnoeas in non-divers (ND) or elite breath-hold divers (EBHD) are unknown. Participants were stratified into EBHD (n=8), ND (n=10) and control (n=8) groups. On two separate occasions EBHD and ND performed a series of five maximal dynamic apnoeas (DYN) or two sets of five maximal static apnoeas (STA). Control performed a static eupnoeic (STE) protocol to control against any effects of water immersion and diurnal variation on EPO. Peripheral oxygen saturation (SpO2) levels were monitored up to 20s post each maximal effort. Blood samples were collected at 30, 90, and 180-min after each protocol for EPO, haemoglobin and haematocrit concentrations. No between group differences were observed at baseline (p>0.05). For EBHD and ND, mean end-apnoea SpO2 was lower in DYN (EBHD,62±10%,p=0.024;ND,85±6%;p=0.020) than STA (EBHD,76±7%;ND,96±1%) and control (98±1%) protocols. EBHD attained lower end-apnoeic SpO2 during DYN and STA than ND (p<0.001). Serum EPO increased from baseline following the DYN protocol in EBHD only (EBHD,p<0.001;ND,p=0.622). EBHD EPO increased from baseline (6.85±0.9mlU/mL) by 60% at 30-min (10.82±2.5mlU/mL,p=0.017) and 63% at 180-min (10.87±2.1mlU/mL,p=0.024). Serum EPO did not change after the STA (EBHD,p=0.534;ND,p=0.850) and STE (p=0.056) protocols. There was a significant negative correlation (r=-0.49,p=0.003) between end-apnoeic SpO2 and peak post-apnoeic serum EPO concentrations. The novel findings demonstrate that circulating EPO is only increased after DYN in EBHD. This may relate to the greater hypoxemia achieved by EBHD during the DYN.

Dual energy X-ray absorptiometry (DXA) is a medical imaging device which has become the method of choice for the measurement of body composition in athletes. The objectives of this review were to evaluate published longitudinal DXA body composition studies in athletic populations for interpretation of 'meaningful' change, and to propose a best practice measurement protocol. An online search of PubMed and CINAHL via EBSCO Host and Web of Science enabled the identification of studies published until November 2016. Those which met the inclusion criteria were reviewed independently by two authors according to their methodological quality and interpretation of body composition change. Twenty-five studies published between 1996 and November 2016 were reviewed (male athletes: 13, female athletes: 3, mixed: 9) and sample sizes ranged from n = 1 to 212. The same number of eligible studies were published between 2013 - 2016, as over the 16 years prior (1996 - 2012). Seven did not include precision error, and fewer than half provided athlete-specific precision error. There were shortfalls in the sample sizes on which precision estimates were based and inconsistencies in the level of pre-scan standardisation, with some reporting full standardisation protocols and others reporting only single (e.g. overnight fast) or no control measures. There is a need for standardised practice and reporting in athletic populations for the longitudinal measurement of body composition using DXA. Based on this review and that of others, plus the official position of the International Society for Clinical Densitometry, our recommendations and protocol are proposed as a guide to support best practice.

Nitrate-rich beetroot juice (BRJ) increases plasma nitrite concentrations, lowers the oxygen cost (V̇O2) of steady-state exercise and improves exercise performance in sedentary and moderately-trained, but rarely in well-trained individuals exercising at sea-level. BRJ supplementation may be more effective in a hypoxic environment, where the reduction of nitrite into nitric oxide (NO) is potentiated, such that well-trained and less well-trained individuals may derive a similar ergogenic effect. We conducted a randomised, counterbalanced, double-blind placebo controlled trial to determine the effects of BRJ on treadmill running performance in moderate normobaric hypoxia (equivalent to 2500 m altitude) in participants with a range of aerobic fitness levels. Twelve healthy males (V̇O2max ranging from 47.1 to 76.8 ml kg(-1)·min(-1)) ingested 138 ml concentrated BRJ (∼15.2 mmol nitrate) or a nitrate-deplete placebo (PLA) (∼0.2 mmol nitrate). Three hours later, participants completed steady-state moderate intensity running, and a 1500 m time-trial (TT) in a normobaric hypoxic chamber (FIO2 ∼15%). Plasma nitrite concentrations were significantly greater following BRJ versus PLA 1 h post supplementation, and remained higher in BRJ throughout the testing session (p < 0.01). Average V̇O2 was significantly lower (BRJ: 18.4 ± 2.0, PLA: 20.4 ± 12.6 ml kg(-1)·min(-1); p = 0.002), whilst arterial oxygen saturation (SpO2) was significantly greater (BRJ: 88.4 ± 2.7, PLA: 86.5 ± 3.3%; p < 0.001) following BRJ. BRJ improved TT performance in all 12 participants by an average of 3.2% (BRJ: 331.1 ± 45.3 vs. PL: 341.9 ± 46.1 s; p < 0.001). There was no apparent relationship between aerobic fitness and the improvement in performance following BRJ (r(2) = 0.05, p > 0.05). These findings suggests that a high nitrate dose in the form of a BRJ supplement may improve running performance in individuals with a range of aerobic fitness levels conducting moderate and high-intensity exercise in a normobaric hypoxic environment.

Exposure to altitude results in multiple physiological consequences. These include, but are not limited to, a reduced maximal oxygen consumption, drop in arterial oxygen saturation, and increase in muscle metabolic perturbations at a fixed sub-maximal work rate. Exercise capacity during fixed work rate or incremental exercise and time-trial performance are also impaired at altitude relative to sea-level. Recently, dietary nitrate (NO3-) supplementation has attracted considerable interest as a nutritional aid during altitude exposure. In this review, we summarise and critically evaluate the physiological and performance effects of dietary NO3- supplementation during exposure to simulated and terrestrial altitude. Previous investigations at simulated altitude indicate that NO3- supplementation may reduce the oxygen cost of exercise, elevate arterial and tissue oxygen saturation, improve muscle metabolic function, and enhance exercise capacity/ performance. Conversely, current evidence suggests that NO3- supplementation does not augment the training response at simulated altitude. Few studies have evaluated the effects of NO3- at terrestrial altitude. Current evidence indicates potential improvements in endothelial function at terrestrial altitude following NO3- supplementation. No effects of NO3- supplementation have been observed on oxygen consumption or arterial oxygen saturation at terrestrial altitude, although further research is warranted. Limitations of the present body of literature are discussed, and directions for future research are provided.

INTRODUCTION: Whilst the link between physical factors and risk of high altitude (HA)-related illness and acute mountain sickness (AMS) have been extensively explored, the influence of psychological factors has been less well examined. In this study we aimed to investigate the relationship between 'anxiety and AMS risk during a progressive ascent to very HA. METHODS: Eighty health adults were assessed at baseline (848m) and over 9 consecutive altitudes during a progressive trek to 5140m. HA-related symptoms (Lake Louise [LLS] and AMS-C Scores) and state anxiety (State-Trait-Anxiety-Score [STAI Y-1]) were examined at each altitude with trait anxiety (STAI Y-2) at baseline. RESULTS: The average age was 32.1 ± 8.3 years (67.5% men). STAI Y-1 scores fell from 848m to 3619m, before increasing to above baseline scores (848m) at ≥4072m (p = 0.01). STAI Y-1 scores correlated with LLS (r = 0.31; 0.24-0.3; P<0.0001) and AMS-C Scores (r = 0.29; 0.22-0.35; P<0.0001). There was significant main effect for sex (higher STAI Y-1 scores in women) and altitude with no sex-x-altitude interaction on STAI Y-1 Scores. Independent predictors of significant state anxiety included female sex, lower age, higher heart rate and increasing LLS and AMS-C scores (p<0.0001). A total of 38/80 subjects (47.5%) developed AMS which was mild in 20 (25%) and severe in 18 (22.5%). Baseline STAI Y-2 scores were an independent predictor of future severe AMS (B = 1.13; 1.009-1.28; p = 0.04; r2 = 0.23) and STAI Y-1 scores at HA independently predicted AMS and its severity. CONCLUSION: Trait anxiety at low altitude was an independent predictor of future severe AMS development at HA. State anxiety at HA was independently associated with AMS and its severity.

INTRODUCTION: Dietary nitrate supplementation increases nitric oxide (NO) bioavailability, and has been shown to improve exercise performance in hypoxia (i.e. a low-oxygen environment) in some (e.g. Muggeridge et al., 2014, Med Sci Sports Exerc, 46:143-150) but not all (e.g. Arnold et al., 2015, Appl. Physiol. Nutr. Metab., 40: 590-595) studies. The precise conditions under which nitrate consumption is ergogenic remains to be established. The aim of this study was to assess the effects of nitrate-rich beetroot juice on the physiological response to steady-state exercise, and 1500 m time-trial (TT) performance in trained runners exercising in moderate normobaric hypoxia (equivalent to 2500 m altitude). METHODS: Six trained runners (age: 23.3 ± 1.9 years; sea-level V̇O2max: 64.6 ± 10.2 ml·kg-1·min-1; altitude V̇O2max: 53.1 ± 7.9 ml·kg-1·min-1) visited the laboratory on five separate occasions, including incremental running tests in normoxia (1) and hypoxia (2) to determine V̇O2max; a familiarization trial (3); and two performance trials (4 + 5). On the morning of the performance trials, participants consumed 138 ml concentrated nitrate-rich (reported to contain ~12.5 mmol nitrate) or a nitrate-deplete (~0 mmol nitrate) beetroot juice. Three hours later, participants completed two, 15 minute steady-state bouts of running at 45 and 65 % of altitude V̇O2max, respectively, and a 1500 m TT in a normobaric hypoxic chamber (PIO2 107.5 mmHg, FIO2 ~15 %). Exhaled NO was measured pre-supplementation, pre-hypoxic exposure, pre-exercise and post-TT. VO2 was monitored during steady-state exercise, and arterial oxygen saturation (SaO2) was monitored pre-hypoxic exposure, pre-exercise, during steady-state exercise, and post-TT. RESULTS: Nitrate supplementation significantly elevated exhaled NO versus placebo (Placebo: 20.5 ± 20.5 vs. Nitrate: 45.5 ± 30.6 p.p.b., p = 0.044). Average VO2 was significantly lower during steady-state exercise (Placebo: 27.6 ± 5.4 vs. Nitrate: 25.0 ± 4.5 ml·kg-1·min-1, p = 0.029), whilst average SaO2 was significantly greater (Placebo: 85.9 ± 2.6 vs. Nitrate: 88.2 ± 2.8 %, p = 0.02) with nitrate ingestion. TT performance was significantly faster (Placebo: 346.8 ± 43.3 s vs. Nitrate: 335.1 ± 42.3 s, p = 0.01, Cohen’s d = 0.272) following nitrate supplementation. CONCLUSION: Dietary nitrate supplementation increases exhaled NO, reduces steady-state VO2, and elevates SaO2 during steady-state exercise, and results in a small (3.4 %) but significant improvement in 1500 m TT performance relative to a placebo. Therefore, nitrate-rich beetroot juice may represent a viable ergogenic aid for enhancing 1500 m running performance in trained athletes exercising in moderate normobaric hypoxia.

Introduction Heat adaptation is protective against heat illness; however, its role in heat syncope, due to reflex mechanisms, has not been conclusively established. The aim of this study was to evaluate if heat acclimation (HA) was protective against heat syncope and to ascertain underlying physiological mechanisms. Methods Twenty (15 males, 5 females) endurance-trained athletes were randomized to either 8 d of mixed active and passive HA (HEAT) or climatically temperate exercise (CONTROL). Before, and after, the interventions participants underwent a head up tilt (HUT) with graded lower body negative pressure (LBNP), in a thermal chamber (32.0 ± 0.3°C), continued until presyncope with measurement of cardiovascular parameters. Heat stress tests (HST) were performed to determine physiological and perceptual measures of HA. Results There was a significant increase in orthostatic tolerance (OT), as measured by HUT/LBNP, in the HEAT group (preintervention; 28 ± 9 min, postintervention; 40 ± 7 min) compared with CONTROL (preintervention; 30 ± 8 mins, postintervention; 33 ± 5 min) (P = 0.01). Heat acclimation resulted in a significantly reduced peak and mean rectal and skin temperature (P < 0.01), peak heat rate (P < 0.003), thermal comfort (P < 0.04), and rating of perceived exertion (P < 0.02) during HST. There was a significantly increased plasma volume (PV) in the HEAT group in comparison to CONTROL (P = 0.03). Conclusions Heat acclimation causes improvements in OT and is likely to be beneficial in patients with heat exacerbated reflex syncope. Heat acclimation–mediated PV expansion is a potential physiological mechanism underlying improved OT.

The ultimate aim of bodybuilding is to achieve an aesthetically pleasing physique through gains in lean tissue mass (LTM) and reductions in fat mass (FM). Favourable blood lipid profile (BLP) adaptations have been reported but research is equivocal. Total energy intake (EI) has been suggested to be one of the biggest dietary predictors for optimum body composition with daily distribution of meals less important. However, high quality protein per meal as a means to maintain muscle protein synthesis suggests that higher daily meal frequency (MF) may be a more appropriate dietary strategy. Our aim was to investigate the interplay between habitual MF, body composition and BLP in non-competitive bodybuilders. Following ethical approval, 44 males and 10 females met participation criteria. Upper and lower 25th percentiles of response to number of eating occasions were calculated. Arranged into a low (LFG, 2.6±0.8) (n=12, 27.9±5.1 years, 80.9±17.8 kg) or high (HFG, 6.6±0.8) (n=12, 27.3±7.2 years, 85.2±16.8 kg) daily MF group, participants (n=24, 27.9±6.1 years, 83.0±17.1 kg), completed a 3-day diet diary, had a dual energy X-ray absorptiometry scan, blood lipids measured. The HFG (13.9±3.8%) had significantly lower (P=0.024) %body fat than the LFG (19.2±6.7%). There was a trend for higher LTM in the HFG (70.2±14.4 kg) compared to the LFG (62.1±14.5 kg). Blood lipids were within normal range, while the HFG completed significantly (P=0.000) more weekly training sessions (4.3±0.8) than the LFG (5.5±0.7). Despite the HFG consuming more energy (2564±681 kcal) than the LFG (2215±533), the difference was not significant. Protein intake in the HFG was significantly higher (P=0.54) than the LFG (2.6±1.0 vs 1.9±0.5 g/kg-1/BW/d-1). Differences were not observed in fat (1.2±0.6 and 1.4±0.6 g/kg-1/BW/d-1) or carbohydrate (2.5±1.4 and 1.9±1.1 g/kg-1/BW/d-1 in LFG and HFG respectively) intakes. In relative terms, the carbohydrate intake in the HFG (25±9.0%) was significantly lower (P=0.027) than that of the LFG (35±12%). In conclusion, BLP was within healthy range in both groups. Furthermore, higher MF was associated with optimum sport-specific body composition outcomes. This is potentially due to higher consumption of dietary proteins (35% of daily EI) resulting in optimisation of muscle synthetic response and training capacity.

The ultimate aim of bodybuilding is to achieve an aesthetically pleasing physique through gains in lean body mass (LBM) and reductions in fat mass (FM). Favourable blood lipid profile (BLP) adaptations have been reported but research is equivocal. Total energy intake (EI) has been suggested to be one of the biggest dietary predictors for optimum body composition with daily distribution of meals less important. However, high quality protein per meal as a means to maintain muscle protein synthesis suggests that higher daily meal frequency (MF) may be a more appropriate dietary strategy. Our aim was to investigate the interplay between habitual MF, body composition and BLP in non-competitive bodybuilders. Following ethics approval, 44 males and 10 females met participation criteria. Upper and lower 25th percentiles of response to number of eating occasions were calculated. Arranged into a low (LFG, 2.6±0.8: n=12, 28±5 years, 80.9±17.8 kg) or high (HFG, 6.6±0.8: n=12, 27±7 years, 85.2±16.8 kg) daily MF group, participants completed a 3-day diet diary, had a dual energy X-ray absorptiometry scan, and blood lipids measured. The HFG (13.9±3.8%) had lower (P=0.024) %body fat than the LFG (19.2±6.7%) but LBM in the HFG (70.2±14.4 kg) was not different from that of the LFG (62.1±14.5 kg). Blood lipids were within healthy range, while the HFG completed more (P=0.000) weekly training sessions (4.3±0.8) than the LFG (5.5±0.7). There was no difference in energy intake between the groups: HFG 2564±681 kcal; LFG 2215±533. Protein intake in the HFG was higher (P=0.054) than the LFG (2.6±1.0 vs 1.9±0.5 g/kg-1/BW/d-1). Differences were not observed in fat (1.2±0.6 and 1.4±0.6 g/kg-1/BW/d-1) or carbohydrate (2.5±1.4 and 1.9±1.1 g/kg-1/BW/d-1 in LFG and HFG respectively) intakes. In relative terms, the carbohydrate intake in the HFG (25±9%) was lower (P=0.027) than that of the LFG (35±12%). In conclusion, BLP was within the healthy range in both groups. Furthermore, higher MF was associated with better sport-specific body composition outcomes. This is potentially due to higher consumption of dietary proteins (35% of daily EI) resulting in optimisation of muscle synthetic response and training capacity.

We investigated 3-compartment body composition across one competitive season in professional male rugby union players using dual-energy X-ray absorptiometry (GE iDXA). Thirty five players from one English Premiership team (forwards: n=20, age: 25.5±4.7 years; backs: n=15, age: 26.1±4.5 years) received one total body DXA scan at pre-season (August), mid-season (January) and end-season (May), enabling quantification of body mass, total and regional fat mass, lean mass, percentage tissue fat mass (%TFM) and bone mineral content (BMC). Both team and individual changes were evaluated, and for the latter, least significant change (LSC) was derived from precision data and applied as per International Society for Clinical Densitometry guidelines. Mean body mass remained stable throughout the season (p>0.05), but total fat mass and %TFM increased from pre to end-season, and mid to end-season (p<0.05). There were also statistically significant increases in total-body BMC across the season (P<0.05). In backs, there was a loss of lean mass between mid and end-season (P<0.01). Individual evaluation using LSC and Bland Altman analysis revealed a meaningful loss of lean mass in 17 players and a gain of fat mass in 21 players from pre to end-season. Twelve players exhibited no change. Strategies to improve the maintenance of pre-season lean/ fat ratios across the season for professional rugby union players might be beneficial to performance and health, and thus require exploration. We recommend that future studies include an individualised approach to DXA body composition monitoring and this can be achieved through application of derived LSC.

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.

The skeleton of a cricket fast bowler is exposed to a unique combination of gravitational and torsional loading in the form of substantial ground reaction forces delivered through the front landing foot, and anterior-posterior shear forces mediated by regional muscle contractions across the lumbo-pelvic region. The objectives of this study were to compare the hip structural characteristics of elite fast bowlers with recreationally-active age-matched controls, and to examine unilateral bone properties in fast bowlers. Dual-energy X-ray absorptiometry (DXA) of the proximal femur was performed in 26 elite male fast bowlers and 26 normally-active controls. Hip structural analysis (GE Lunar; enCORE version 15.0) determined areal bone mineral density (BMD) of the proximal femur, and cross-sectional area (CSA), section modulus (Z), cross-sectional moment of inertia (CSMI) and femoral strength index (FSI) at the narrow region of the femoral neck. Mean femoral neck and trochanter BMD were greater in fast bowlers than controls (p < 0.001). All bone geometry properties except for CSMI were superior in fast bowlers (p < 0.05) following adjustment for height and lean mass. There were no asymmetries in BMD or bone geometry when considering leg dominance of the fast bowlers (p > 0.05). Elite fast bowlers have superior bone characteristics of the proximal femur, with results inferring enhanced resistance to axial compression (CSA), and bending (Z) forces, and enhanced strength to withstand a fall impact as indicated by their higher FSI. No asymmetries in hip bone properties were identified, suggesting that both torsional and gravitational loading offer significant osteogenic potential.

Purpose This study evaluated the effects of dietary nitrate (NO3-) supplementation on physiological functioning and exercise performance in trained runners/ triathletes conducting short and longer distance treadmill running time-trials (TT). Method Eight trained male runners or triathletes completed four exercise performance tests comprising a 10 minute warm up followed by either a 1500 m or 10,000 m treadmill TT. Exercise performance tests were preceded 3 hours before the exercise by supplementation with either 140 ml concentrated nitrate-rich (~ 12.5 mmol nitrate) (BRJ) or nitrate-deplete (~ 0.01 mmol nitrate) (PLA) beetroot juice. Results BRJ supplementation significantly elevated plasma [NO2-] (P < 0.05). Resting blood pressure and exercise V̇O2 were not significantly different between BRJ and PLA (P > 0.05). However, post-exercise blood [lactate] was significantly greater in BRJ following the 1500 m TT (6.6 ± 1.2 vs. 6.1 ± 1.5 mM; P < 0.05), but not significantly different between conditions in the 10,000 m TT (P > 0.05). Performance in the 1500 m TT was significantly faster in BRJ versus PLA (319.6 ± 36.2 vs. 325.7 ± 38.8 s; P < 0.05). Conversely, there was no significant difference in 10,000 m TT performance between conditions (2643.1 ± 324. 1 vs. 2649.9 ± 319.8 s, P > 0.05). Conclusion Acute BRJ supplementation significantly enhanced 1500 m but not 10,000 m TT performance. These findings suggest that BRJ might be ergogenic during shorter-distance TTs which allow for a high work rate, but not during longer-distance TTs, completed at a lower work rate.

Central arterial systolic blood pressure (SBP) and arterial stiffness are known to be better predictors of adverse cardiovascular outcomes than brachial SBP. The effect of progressive high altitude (HA) on these parameters has not been examined. Ninety healthy adults were included. Central BP and the augmentation index (AI) were measured at the level of the brachial artery (Uscom BP + device) at <200 m and at 3619, 4600 and 5140 m. The average age of the subjects (70% men) were 32.2±8.7 years. Compared with central arterial pressures, brachial SBP (+8.1±6.4 mm Hg; P<0.0001) and pulse pressure (+10.9±6.6 mm Hg; P<0.0001) were significantly higher and brachial diastolic BP was lower (-2.8±1.6 mm Hg; P<0.0001). Compared with <200 m, HA led to a significant increase in brachial and central SBP. Central SBP correlated with AI (r=0.50; 95% confidence interval (CI): 0.41-0.58; P<0.0001) and age (r=0.32; 95% CI: 21-0.41; P<0.001). AI positively correlated with age (r=0.39; P<0.001) and inversely with subject height (r=-0.22; P<0.0001), weight (r=-0.19; P=0.006) and heart rate (r=-0.49; P<0.0001). There was no relationship between acute mountain sickness scores (Lake Louis Scoring System (LLS)) and AI or central BP. The independent predictors of central SBP were male sex (coefficient, t=4.7; P<0.0001), age (t=3.6; P=0.004) and AI (t=7.5; P<0.0001; overall r 2 =0.40; P<0.0001). Subject height (t=2.4; P=0.02), age (7.4; P<0.0001) and heart rate (t=11.4; P<0.0001) were the only independent predictors of AI (overall r 2 =0.43; P<0.0001). Central BP and AI significantly increase at HA. This rise was influenced by subject-related factors and heart rate but not independently by altitude, LLS or SpO 2.

The purpose of this study was to assess the reliability of a pre-loaded 1500 m treadmill time-trial, conducted in moderate normobaric hypoxia. Eight trained runners/ triathletes (24 ± 3 years, 73.2 ± 8.1 kg, 182.5 ± 6.5 cm, altitude specific V̇O2max: 52.9 ± 5.5 ml·kg-1·min-1) completed three trials (the first as a familiarisation), involving two, 15 minute running bouts at 45 % and 65 % V̇O2max, respectively, and a 1500 m time-trial in moderate normobaric hypoxia equivalent to a simulated altitude of 2500 m (FiO2 ~ 15 %). Heart rate, arterial oxygen saturation, skeletal muscle and cerebral tissue oxygenation (StO2), expired gas (V̇O2 and V̇CO2), and ratings of perceived exertion were monitored. Running performance (Trial 1: 352.7 ± 40; Trial 2: 353.9 ± 38.2 s) demonstrated a low CV (0.9 %) and high ICC (1). All physiological variables demonstrated a global CV ≤ 4.2 %, and ICC ≥ 0.87, with the exception of muscle (CV 10.4 %; ICC 0.70) and cerebral (CV 4.1 %; ICC 0.82) StO2. These data demonstrate good reliability of the majority of physiological variables, and indicate that a pre-loaded 1500 m time-trial conducted in moderate normobaric hypoxia is a highly reliable test of performance.

Super League (SL) and Championship (RLC) rugby league players will compete against each other in 2015 and beyond. To identify possible discrepancies, this study compared the anthropometric profile and body composition of current SL (full-time professional) and RLC (part-time semi-professional) players using dual-energy X-ray absorptiometry (DXA). A cross-sectional design involved DXA scans on 67 SL (n=29 backs, n=38 forwards) and 46 RLC (n=20 backs, n=26 forwards) players during preseason. A one-way ANOVA was used to compare age, stature, body mass, soft tissue fat percentage, bone mineral content (BMC), total and regional (i.e., arms, legs and trunk) fat and lean mass between SL forwards, SL backs, RLC forwards and RLC backs. No significant differences in age, stature or body mass were observed. SL forwards and backs had relatively less soft tissue fat (17.5 ± 3.7 and 14.8 ± 3.6 vs. 21.4 ± 4.3 and 20.8 ± 3.8%), greater BMC (4,528 ± 443 and 4,230 ± 447 vs. 4,302 ± 393 and 3,971 ± 280 g), greater trunk lean mass (37.3 ± 3.0 and 35.3 ± 3.8 vs. 34.9 ± 32.3 and 32.3 ± 2.6 kg) and less trunk fat mass (8.5 ± 2.7 and 6.2 ± 2.1 vs. 10.7 ± 2.8 and 9.5 ± 2.9 kg) than RLC forwards and backs. Observed differences may reflect selection based on favourable physical attributes, or training adaptations. To reduce this discrepancy, some RLC players should reduce fat mass and increase lean mass, which may be of benefit for the 2015 season and beyond.

The assessment of body size and body composition is essential when evaluating and monitoring the development of Academy rugby league (RL) players. To date, no study has explored relative three-compartment body composition in Academy players compared to professional Super League (SL) players. The purpose of this study was to compare body size and relative body composition in Academy RL players and SL players using dual energy X-ray absorptiometry (DXA). With institutional research ethics approval, 63 European SL players from two clubs (backs: n = 25, age 25.7 ± 4.3 years; forwards: n = 38, age 26.1 ± 4.9 years) and 32 Academy players from one club (backs: n = 14, age 18.1 ± 1.0 years; forwards: n = 18, age 18.1 ± 0.9 years), received one total-body DXA scan (Lunar iDXA, GE Healthcare Little Chalfont, Buckinghamshire) during pre-season, in a euhydrated state (urine osmolality <700 mOsmol · kg-1). The regions of interest on scan images were manually adjusted where necessary by a qualified densitometrist, according to manufacturer guidelines. Independent t-tests compared height, body mass and percentage body fat (%BF). Multivariate analysis with height and body mass as covariates, examined positional differences in body composition by level. Effect size was calculated using Cohen’s d. SL players were taller (backs: 181.3 ± 6.1 vs. 179.5 ± 5.3 cm; forwards: 184.3 ± 5.5 vs. 179.1 ± 6.2 cm; P = 0.005, d = 0.33–0.89) and heavier (backs: 90.2 ± 9.1 vs. 83.1 ± 6.8 kg; forwards: 99.8 ± 8.1 vs. 90.1 ± 9.0 kg; P < 0.001, d = 0.88–1.13) than Academy players. %BF was greater in Academy compared to SL forwards (20.1 ± 3.0 vs. 17.5 ± 3.7%; P = 0.01, d = 0.77), but similar between levels in backs (16.1 ± 3.0 vs. 14.9 ± 3.6 %). In Academy forwards, total fat mass (FM) was greater (?3.0 (s x 0.9) kg, P = 0.009, d = 0.85), and total lean mass (LM) was lower (? -2.8 (0.9) kg, P = 0.016, d = 0.88) than in SL forwards. Relative to body size, total and regional FM, LM and BMC in Academy backs were similar to SL backs. Academy forwards had greater arm and leg FM than SL forwards (?2.7 (1.0) kg, P = 0.05, d = 0.83; ?1.7 (0.3) kg P < 0.001, d = 1.5) and lower arm (?-58.1 (16.3) g, P = 0.004, d = 1.03) and trunk (?-92.4 (31.4) g, P = 0.025, d = 0.78) BMC. Our findings of lower LM and BMC relative to body size in Academy forwards suggest that these players are still developing. This corresponds with longitudinal reports elsewhere that the majority of adult fat-free mass is achieved during the late second to early third decade, following the attainment of adult height and bone size. The longitudinal tracking of body size and composition of Academy RL players to senior level is a direction for future research.

Body composition analysis is regularly conducted in professional rugby union (RU) players to monitor changes in body mass (BM), fat mass (FM), lean mass (LM), percentage body fat (%BF) and bone mineral content (BMC). It would be desirable for RU players to maintain LM for the duration of the season, due to the high levels of muscular power and strength required for performance. To date, the seasonal changes in body composition associated with professional RU have not been documented. The purpose was to investigate acute changes in body composition during a competitive season in professional RU players using dual energy X-ray absorptiometry (DXA). With institutional ethical approval, players were recruited from an English Premiership club (n = 23, age: 25.9 ± 4.7 years, height: 187.2 ± 7.7 cm). Players received one total-body DXA scans (Lunar iDXA, GE Healthcare) during three phases of the competitive season (pre-season (August), mid-season (January) and post-season (May)) in a euhydrated state (urine osmolality

Abstract

Body composition assessments in professional male football often lack sport-specific evidence, risking mismanagement of player health and performance. This study described dual-energy X-ray absorptiometry (DXA)-derived values by playing position, ethnicity, competition level, and seasonal timepoints. A total of 343 players (mean ± SD: age = 22.6 ± 4.6 years; stature = 182.0 ± 6.9 cm; body mass = 79.1 ± 8.6 kg) from the English Premier League (n = 76) and English Football League (n = 267) completed 939 scans over a 10-year period (2014–2024) using DXA (Lunar iDXA, GE Healthcare), with repeat measurements taken across the season. Players were sub-classified as Goalkeepers (n = 32), Central Defenders (n = 55), Wide Defenders (n = 64), Central Midfielders (n = 73), Wide Midfielders (n = 62), and Forwards (n = 57). Body composition ranges specific to position were identified for bone mass (3.5–4.2 kg), lean mass (61.2–69.6 kg), fat mass (9.1–13.5 kg), and percentage body fat (11.6–15.4%). Significant differences in bone, lean, and fat mass were observed between playing positions, ethnicity, and league level ( p  < 0.050). Across a single season, fat-free mass increased significantly, while fat mass decreased (both: p  < 0.001), indicating positive physiological adaptations from moderate body mass increases rather than performance concerns. These findings indicate that body fat values above the commonly cited < 10% threshold are regularly observed in elite male footballers, suggesting the need for more individualised targets over generic team-wide standards. Providing the largest criterion-measured dataset for professional male footballers, this study supports athlete-centred, position-specific decision-making to optimise player health and performance.

The British Service Dhaulagiri Research Expedition took place in March-May 2016. A total of 129 personnel took part in the expedition and were invited to consent to a variety of study protocols investigating adaptation to high altitudes and diagnosis of altitude illness. The study took place in a remote and inhospitable environment at altitudes up to 7500m. This paper gives an overview of the challenges involved, the research protocols investigated and the execution of the expedition in Nepal.

The purpose of this study was to investigate longitudinal body composition of professional rugby union players over one competitive season. Given the potential for variability in changes, and as the first to do so, we conducted individual analysis in addition to analysis of group means. Thirty-five professional rugby union players from one English Premiership team (forwards: n = 20, age: 25.5 ± 4.7 years; backs: n = 15, age: 26.1 ± 4.5 years) received one total-body dual-energy X-ray absorptiometry (DXA) scan at preseason (August), midseason (January) and endseason (May), enabling quantification of body mass, total and regional fat mass, lean mass, percentage tissue fat mass (%TFM) and bone mineral content (BMC). Individual analysis was conducted by applying least significant change (LSC), derived from our previously published precision data and in accordance with International Society for Clinical Densitometry (ISCD) guidelines. Mean body mass remained stable throughout the season (p > 0.05), but total fat mass and %TFM increased from pre to endseason, and mid to endseason (p < 0.05). There were also statistically significant increases in total-body BMC across the season (p < 0.05). In both groups, there was a loss of lean mass between mid and endseason (p < 0.018). Individual evaluation using LSC and Bland-Altman analysis revealed a meaningful loss of lean mass in 17 players and a gain of fat mass in 21 players from pre to endseason. Twelve players had no change and there were no differences by playing position. There were individual gains or no net changes in BMC across the season for 10 and 24 players, respectively. This study highlights the advantages of an individualised approach to DXA body composition monitoring and this can be achieved through application of derived LSC.

This study investigated the change in body composition and bone mineral content (BMC) of senior rugby league players between 2008 and 2014. Twelve male professional rugby league players (age, 24.6±4.0 years; stature, 183.4±8.4 cm) received a DXA scan during pre-season in 2008 and 2014. Between 2008 and 2014, very likely increases in leg lean mass, total trunk and leg BMC, and a likely increase in arm BMC and possible increases in body mass, total and trunk fat mass, and total, trunk and arm lean mass were observed. Unlikely decreases and unclear changes in leg and arm fat mass were also found. Large negative correlations were observed between age and body mass (r=-0.72), lean mass (r=-0.70), fat mass (r=-0.61), and BMC (r=-0.84) change. Three participants (19.1 ± 1.6 years) increased lean mass by 7.0 – 9.3 kg. Younger players had the largest increases in lean mass during this period, although an older player (30 year-old) still increased lean mass. Differences in body composition change were also observed for participants of the same age, thus contextual factors should be considered. This study demonstrates the individuality of body composition changes in senior professional rugby players, while considering the potential change in young athletes.

Purpose: This study compared the body size and three compartment body composition between academy and senior professional rugby league players using dual energy X-ray absorptiometry (DXA). Methods: Academy (age 18.1±1.1 years; n=34) and senior (age 26.2 ±4.6 years; n=63) rugby league players received one total-body DXA scan. Height, body mass and body fat percentage alongside total and regional fat mass, lean mass and bone mineral content (BMC) were compared. Independent t-tests with Cohen’s d effect sizes and multivariate analysis of covariance (MANCOVA), controlling for height and body mass, with partial eta squared (η2) effect sizes, were used to compare total and regional body composition. Results: Senior players were taller (183.2±5.8 vs. 179.2±5.7 cm; p=0.001; d=0.70) and heavier (96.5±9.3 vs. 86.5±9.0 kg; p<0.001; d=1.09) with lower body fat percentage (16.3±3.7 vs. 18.0±3.7 %; p=0.032; d=0.46) than academy players. MANCOVA identified significant overall main effects for total and regional body composition between academy and senior players. Senior players had lower total fat mass (p<0.001, η2=0.15), greater total lean mass (p<0.001, η2=0.14) and greater total BMC (p=0.001, η2=0.12) than academy players. For regional sites, academy players had significantly greater fat mass at the legs (p<0.001; η2=0.29) than senior players. Conclusions: The lower age, height, body mass and BMC of academy players suggest that these players are still developing musculoskeletal characteristics. Gradual increases in lean mass and BMC whilst controlling fat mass is an important consideration for practitioners working with academy rugby league players, especially within the lower body.

Body composition analysis using dual energy X-ray absorptiometry (DXA) is becoming increasingly popular in both clinical and sports science settings. Obesity, characterised by high fat mass (FM), is associated with larger precision errors, however, precision error for athletic groups with high levels of lean mass (LM) are unclear. Total (TB) and regional (limbs and trunk) body composition were determined from two consecutive total body scans (GE Lunar iDXA) with re-positioning in 45 elite male rugby league players (age: 21.8 ±5.4 years BMI: 27.8 ±2.5 kg.m-1). The root mean squared standard deviation (percentage co-efficient of variation) were TB bone mineral content (BMC): 24g (1.7%), TB LM: 321g (1.6%), and TB FM: 280g (2.3%). Regional precision values were superior for measurements of BMC: 4.7-16.3g (1.7-2.1%) and LM: 137-402g (2.0-2.4%), than for FM: 63-299g (3.1-4.1%). Precision error of DXA body composition measurements in elite male rugby players is higher than those reported elsewhere for normal adult populations and similar to those reported in those who are obese. It is advised that caution is applied when interpreting longitudinal DXA-derived body composition measurements in male rugby players and population-specific least significant change should be adopted.

Recent research has demonstrated that greater player body mass, lean mass (LM) and lower percentage body fat (%BF) are positively related to rugby league performance (e.g. Gabbett et al., 2011, Journal of Sports Sciences, 29, 1655–1664). Correspondingly, over recent years, there has been an increasing emphasis on player size and muscularity in the professional sport. However, to date, there has been no published data on the longitudinal changes in the body composition of senior professional rugby league players. Therefore, the purpose of this study was to investigate changes in three-compartment body composition over six years, in UK professional rugby league players using dual energy X-ray absorptiometry (DXA). Following institutional ethical approval, 12 professional rugby league players (baseline age: 25.0 ± 3.9 years, height: 183.4 ± 8.4 cm) from one European Super League club received total body DXA scans (Lunar iDXA, GE Healthcare) midseason in 2008 and 2014 when euhydrated (urine osmolality < 700 mOsmol · kg−1). The regions of interest on scan images were checked and manually adjusted where necessary by a qualified densitometrist according to DXA manufacturer guidelines. The primary outcomes were total body mass, %BF, total and regional fat mass (FM), LM and bone mineral content (BMC). A repeated measures multivariate analysis of variance (MANOVA), controlling for chronological age, examined differences between the two time points. Effect sizes were calculated. The repeated measures MANOVA found an overall significant effect for time (P = 0.048, = 0.99). Univariate analysis identified increases in total body mass (95.3 ± 12.2 vs. 98.5 ± 12.2 kg, P = 0.005, d = 0.26), total LM (77.2 ± 8.6 vs. 79.8 ± 9.6 kg, P = 0.006, d = 0.29) and leg LM (25.8 ± 2.8 vs. 27.6 ± 3.8 kg, P = 0.049, d = 0.54) across the six-year period. Increases were also found for total BMC (4324 ± 566 vs. 4575 ± 582 g, P < 0.001, d = 0.44) and BMC at the arms (P = 0.006, d = 0.36), legs (P = 0.001, d = 0.43) and trunk (P < 0.001, d = 0.45) regions over the six-year period. No changes were identified in %BF or FM across the six-year period. This study demonstrates that senior professional rugby league players competing in the European Super League over a six-year period have increased total body mass, which can be predominantly explained by a gain in LM of the lower body. Such findings may reflect the increasing physical demands of the professional game and a greater emphasis on lower body resistance training. These players had remained competitive in the professional sport for six years, which suggests that increasing LM and BMC may be beneficial to career longevity.

Abstract

This is the first study to assess longitudinal changes in anthropometric, physiological, and physical qualities of international women’s rugby league players. Thirteen forwards and 11 backs were tested three times over a 10-month period. Assessments included: standing height and body mass, body composition measured by dual x-ray absorptiometry (DXA), a blood panel, resting metabolic rate (RMR) assessed by indirect calorimetry, aerobic capacity (i.e., VLO 2 max) evaluated by an incremental treadmill test, and isometric force production measured by a force plate. During the pre-season phase, lean mass increased significantly by ∼2% for backs (testing point 1: 47 kg; testing point 2: 48 kg) and forwards (testing point 1: 50 kg; testing point 2: 51 kg) (p = ≤ 0.05). Backs significantly increased their VLO 2 max by 22% from testing point 1 (40 ml·kg −1 ·min −1 ) to testing point 3 (49 ml·kg −1 ·min −1 ) (p = ≤ 0.04). The VLO 2 max of forwards increased by 10% from testing point 1 (41 ml·kg −1 ·min −1 ) to testing point 3 (45 ml·kg −1 ·min −1 ), however this change was not significant (p = ≥ 0.05). Body mass (values represent the range of means across the three testing points) (backs: 68 kg; forwards: 77-78 kg), fat mass percentage (backs: 25-26%; forwards: 30-31%), resting metabolic rate (backs: 7 MJ·day −1 ; forwards: 7 MJ·day −1 ), isometric mid-thigh pull (backs: 2106-2180 N; forwards: 2155-2241 N), isometric bench press (backs: 799-822 N; forwards: 999-1024 N), isometric prone row (backs: 625-628 N; forwards: 667-678 N) and bloods (backs: ferritin 21-29 ug/L, haemoglobin 137-140 g/L, iron 17-21 umol/L, transferrin 3 g/L, transferring saturation 23-28%; forwards: ferritin 31-33 ug/L, haemoglobin 141-145 g/L, iron 20-23 umol/L, transferrin 3 g/L, transferrin saturation 26-31%) did not change (p = ≥ 0.05). This study provides novel longitudinal data which can be used to better prepare women rugby league players for the unique demands of their sport, underpinning female athlete health.

Purpose: Nitric oxide (NO) bioavailability is reduced during acute altitude exposure, contributing towards the decline in physiological and cognitive function in this environment. This study evaluated the effects of nitrate (NO3-) supplementation on NO bioavailability, physiological and cognitive function, and exercise performance at moderate and very-high simulated altitude. Methods: Ten males (mean (SD): V̇O2max: 60.9 (10.1) ml·kg-1·min-1) rested and performed exercise twice at moderate (~14.0 % O2; ~3000 m) and twice at very-high (~11.7% O2; ~4300 m) simulated altitude. Participants ingested either 140 ml concentrated NO3--rich (BRJ; ~12.5 mmol NO3-) or NO3--deplete (PLA; 0.01 mmol NO3-) beetroot juice 2 hours before each trial. Participants rested for 45 minutes in normobaric hypoxia prior to completing an exercise task. Exercise comprised a 45 minute walk at 30 % V̇O2max and a 3 km time-trial (TT), both conducted on a treadmill at a 10 % gradient whilst carrying a 10 kg backpack to simulate altitude hiking. Plasma nitrite concentration ([NO2-]), peripheral oxygen saturation (SpO2), pulmonary oxygen uptake (V̇O2), muscle and cerebral oxygenation, and cognitive function were measured throughout. Results: Pre-exercise plasma [NO2-] was significantly elevated in BRJ compared with PLA (p = 0.001). Pulmonary V̇O2 was reduced (p = 0.020), and SpO2 was elevated (p = 0.005) during steady-state exercise in BRJ compared with PLA, with similar effects at both altitudes. BRJ supplementation enhanced 3 km TT performance relative to PLA by 3.8 % (1653.9 (261.3) vs. 1718.7 (213.0) s) and 4.2 % (1809.8 (262.0) vs. 1889.1 (203.9) s) at 3000 m and 4300 m, respectively (p = 0.019). Oxygenation of the gastrocnemius was elevated during the TT consequent to BRJ (p = 0.011). The number of false alarms during the Rapid Visual Information Processing Task tended to be lower with BRJ compared with PLA prior to altitude exposure (p = 0.056). Performance in all other cognitive tasks did not differ significantly between BRJ and PLA at any measurement point (p ≥ 0.141). Conclusion: This study suggests that BRJ improves physiological function and exercise performance, but not cognitive function, at simulated moderate and very-high altitude

Background: Body composition and bone health are important for netball from a performance and health perspective (e.g., bone stress injury), given the typical characteristics of players and demands of the game. Objectives: The objectives of this study are to quantify and compare the positional group-specific body composition and site-specific bone health outcomes of netball players and to establish within-season changes in these variables. Methods: Forty-seven female netball players (senior: n=23, under-21: n=24) from one Netball Super League (NSL) franchise participated across three seasons (2021-2023). Dual-energy X-ray absorptiometry (DEXA) scans were conducted four times per season. Total body, anteroposterior lumbar spine and total hip scans were performed. General and generalised linear mixed models were used to compare positional groups and age groups, and to investigate within-season changes. Results: Goal circle netball players had greater total mass and bone mass than midcourt netball players at both levels (p<0.05, effect size: moderate to very large), but not when scaled for height. Senior players had greater lean mass, bone mass, total bone mineral density and bone mineral content than under-21 players (p<0.05, effect size: moderate to very large). No group-level significant changes were observed across a playing season, but individual trends varied. Conclusion: These findings highlight the importance of continued physical development in the under-21 squad before progressing to a senior squad, as well as the need for individualised approaches to nutritional and training interventions that support physical development, addressing positional requirements and developmental stages. Future research should explore longitudinal body composition trajectories across career phases and multiple teams to refine normative benchmarks.

This is the first study to assess longitudinal changes in anthropometric, physiological, and physical qualities of international women’s rugby league players. Thirteen forwards and 11 backs were tested three times over a 10-month period. Assessments included: standing height and body mass, body composition measured by dual x-ray absorptiometry (DXA), a blood panel, resting metabolic rate (RMR) assessed by indirect calorimetry, aerobic capacity (i.e.,V˙O2max) evaluated by an incremental treadmill test, and isometric force production measured by a force plate. During the pre-season phase, lean mass increased significantly by ~2% for backs (testing point 1: 47 kg; testing point 2: 48 kg) and forwards (testing point 1: 50 kg; testing point 2: 51 kg) (p = ≤ 0.05). Backs significantly increased their V˙O2max by 22% from testing point 1 (40 ml kg-1 min-1) to testing point 3 (49 ml kg-1 min-1) (p = ≤ 0.04). The V˙O2max of forwards increased by 10% from testing point 1 (41 ml kg-1 min-1) to testing point 3 (45 ml kg-1 min-1), however this change was not significant (p = ≥ 0.05). Body mass (values represent the range of means across the three testing points) (backs: 68 kg; forwards: 77–78 kg), fat mass percentage (backs: 25–26%; forwards: 30–31%), resting metabolic rate (backs: 7 MJ day-1; forwards: 7 MJ day-1), isometric mid-thigh pull (backs: 2106–2180 N; forwards: 2155–2241 N), isometric bench press (backs: 799–822 N; forwards: 999–1024 N), isometric prone row (backs: 625–628 N; forwards: 667–678 N) and bloods (backs: ferritin 21–29 ug/L, haemoglobin 137–140 g/L, iron 17–21 umol/L, transferrin 3 g/L, transferring saturation 23–28%; forwards: ferritin 31–33 ug/L, haemoglobin 141–145 g/L, iron 20–23 umol/L, transferrin 3 g/L, transferrin saturation 26–31%) did not change (p = ≥ 0.05). This study provides novel longitudinal data which can be used to better prepare women rugby league players for the unique demands of their sport, underpinning female athlete health.