Dr Lauren Duckworth

Objective: To investigate whether the 'overnight second-meal effect' results in altered substrate oxidation during the postprandial period following breakfast and subsequent sub-maximal exercise in women. Subjects/Methods: Seven recreationally active women were recruited for the study. In each trial, participants were provided with their evening meal on day 1, which was composed of either high glycaemic index (HGI) or low glycaemic index (LGI) carbohydrates (CHO). On day 2, participants were provided with a standard HGI breakfast and then performed a 60 min run at 65% VȮ2 max 3h later. Results: The incremental area under the curve (IAUC) for plasma glucose concentrations during the postprandial period following breakfast was greater in the HGI trial compared to the LGI trial (P<0.01). Similarly, the IAUC for serum insulin concentrations was greater in the HGI trial than the LGI trial (P<0.05). No differences in plasma free-fatty acids (FFA) or plasma glycerol concentrations were found between trials during the postprandial period. During subsequent exercise, there were no significant differences in substrate metabolism. Conclusion: The glycaemic index of an evening meal does not alter substrate oxidation at rest following breakfast or during subsequent submaximal exercise in women. This study provides further evidence for the overnight second-meal effect on glycaemic responses following a LGI mixed evening meal.

OBJECTIVE: To investigate whether the 'overnight second-meal effect' results in altered substrate oxidation during the postprandial period following breakfast and subsequent sub-maximal exercise in women. SUBJECTS/METHODS: Seven recreationally active women were recruited for the study. In each trial, participants were provided with their evening meal on day 1, which was composed of either high glycaemic index (HGI) or low glycaemic index (LGI) carbohydrates (CHO). On day 2, participants were provided with a standard HGI breakfast and then performed a 60 min run at 65% \[V.]O(2 max) 3 h later. RESULTS: The incremental area under the curve (IAUC) for plasma glucose concentrations during the postprandial period following breakfast was greater in the HGI trial compared to the LGI trial (P<0.01). Similarly, the IAUC for serum insulin concentrations was greater in the HGI trial than the LGI trial (P<0.05). No differences in plasma free-fatty acids (FFA) or plasma glycerol concentrations were found between trials during the postprandial period. During subsequent exercise, there were no significant differences in substrate metabolism. CONCLUSION: The glycaemic index of an evening meal does not alter substrate oxidation at rest following breakfast or during subsequent submaximal exercise in women. This study provides further evidence for the overnight second-meal effect on glycaemic responses following a LGI mixed evening meal.

The beneficial effects of acute carbohydrate (CHO) supplementation on exercise performance have been well described. Also reported is the attenuation of perceived exertion and enhancement of affect during prolonged exercise following CHO ingestion. However, no studies to date have assessed the impact of the type of CHO ingested on affective responses during moderate intensity exercise, lasting 60min or less. Therefore, the aim of the present study was to investigate the effects of consuming a galactose (GAL) CHO drink versus a glucose (GLU) CHO or placebo (PLA) drink before and during exercise on affect and perceived exertion. Nine recreationally active females undertook three trials, each consisting of running for 60min at 65% VO2max followed immediately by a 90min rest period. Prior to (300ml) and at every 15min during exercise (150ml), participants consumed either a GLU or GAL drink each containing 45g of CHO, or an artificially-sweetened PLA drink. Ratings of pleasure-displeasure and perceived activation were measured throughout exercise and the rest period and measures of perceived exertion were measured during exercise. Plasma glucose and serum insulin were significantly greater throughout exercise and rest following the GLU trial compared with the GAL and PLA trials (P<0.05). Measures of perceived activation and pleasure-displeasure were not enhanced nor RPE reduced as a result of ingestion of a CHO solution. In conclusion, the GAL beverage elicited a more favourable metabolic profile in the exercising females but this did not translate into an enhanced affective profile. Indeed, CHO ingestion had no noticeable effect on the assessed psychological indices during 60min of moderate-intensity exercise in females. It is suggested that the maintenance of a positive affective profile may be explained more by the level of hydration as opposed to fuel availability. Therefore, those seeking to use beverages containing CHO to enhance their exercise experience may take note of these findings as this practise appears unjustified. © 2013 Elsevier Ltd.

The primary aim of this narrative review is to evaluate the efficacy of essential amino acid (EAA) supplementation as a strategy to increase dietary protein intake and improve muscle mass, strength and function in older adults. A sufficient daily protein intake is widely recognised to be fundamental for the successful management of sarcopenia in older undernourished adults. In practice, optimising protein intakes in older adults is complex, requiring consideration of the dose and amino acid composition (i.e. a complete EAA profile and abundant leucine content) of ingested protein on a per meal basis, alongside the age-related decline in appetite and the satiating properties of protein. Recent studies in older adults demonstrate that EAA-based supplements are non-satiating and can be administered alongside food to enhance the anabolic properties of a meal containing a suboptimal dose of protein; an effect magnified when combined with resistance exercise training. These findings support the notion that EAA supplementation could serve as an effective strategy to improve musculoskeletal health in older adults suffering from non-communicable diseases such as sarcopenia. Compliance is critical for the long-term success of complex interventions. Hence, aspects of palatability and desire to eat are important considerations regarding EAA supplementation. In conclusion, EAA-based supplements enriched with L-Leucine offer an alternative strategy to whole protein sources to assist older adults in meeting protein recommendations. In practice, EAA supplements could be administered alongside meals ofwith suboptimal protein contentintakes, or alternatively between meals on occasions when older adults achieve their per meal protein intake recommendations.

Throughout a rugby league (RL) season players are exposed to a high volume of competitive fixtures. Cumulative loads and inadequate nutrition may supress immune function, which would have negative consequences for health and performance. As no study has monitored immune function and dietary intake throughout a RL season, the aim of the study was to identify the pattern of dietary intake and critical time points where immune function and selected performance monitors are compromised. Following ethics approval, 20 male volunteer professional RL players (25.4±3.2 y, 98.2±8.4 kg) were monitored the day prior to a competitive fixture for 25 weeks of the season. Weekly changes in neuromuscular function (CMJ), wellbeing (5-point questionnaire), training loads (sRPE), salivary testosterone (sTest) and immunoglobulin A (sIgA) were recorded. Dietary intake (4-day food diary) was assessed at the start, middle and end of the season. Changes from the overall mean were inferred via Cohen’s d effect sizes using means and standard deviations which were calculated from a linear mixed model to account for missing data. Moderate increases in training load occurred in weeks 3, 5, 9, 10, 12 and 20 and a very large increase occurred in week 21. Moderate decreases in CMJ flight time occurred in week 14 and small decreases occurred in weeks 6, 7, 20, 22, 24, 25. For all wellbeing parameters small decreases occurred in weeks 7 and 17 with small increases in stress, soreness and fatigue also occurring in week 20. Mean sTest was 119.8±55.5 pg.ml-1 with small declines occurring in week 7, 10, 13, 20 and 22. Overall sIgA concentrations ranged from 1.03-1.18 µg.min-1, but compared to the overall mean (1.12 ± 0.17 µg.min-1) small decreases were observed in weeks 6, 9, 16, 21, 23, 24. Dietary intakes were consistent during the recording periods with mean energy intake ranging from 2811-3149 kcal.day-1. Carbohydrate, protein, and fat intakes ranged from 2.9-3.2 g.kg.BM-1, 2.0-2.1 g.kg.BM-1, and 1.1-1.4 g.kg.BM-1 respectively. The findings suggest that a consistent intake throughout a competitive season did not prevent reductions in immune function and selected performance monitors. Further research to develop appropriate periodised nutritional strategies to maintain immune function and support player health and performance is needed.

Background: Limited empirical evidence exists which has direct translation for nutrition practitioners working with team sport athletes. Furthermore, given the lack of rugby specific nutrition recommendations, it is important to provide a framework on the requirements of players in order to enhance the standard of nutritional practice in rugby. The primary aim of this research was to develop an expert consensus on optimum nutritional practices of rugby players. Methods: To obtain expert opinion, a Delphi Poll was implemented; this survey technique allows a consensus to be established where information is currently contradictory or insufficient (1). Following ethics approval, seven expert nutrition practitioners from across the United Kingdom (UK) and Ireland were recruited for the study. Practitioners were required to have at least two years continuous experience in professional rugby clubs. All recruited practitioners had at least three years elite experience and were working with international rugby teams at the time of data collection. During the initial stage of the research, three of the UK national nutrition leads were invited to participate in standardised open-ended interviews. A total of 359 statements, divided into 20 topic areas were generated from these interviews and were included in the first round of voting in the Delphi poll. Using a 5-point likert scale, all practitioners selected their level of agreement with the statements from strongly disagree to strongly agree. For a statement to be agreed upon as good practice, 75% of the practitioners were required to vote in agreement. Statements which were not agreed upon were recirculated for the second round of voting. During the first round of voting, all practitioners were invited to provide additional statements for inclusion in the final round. Results: Following the two rounds of voting a total of 201 statements were agreed upon, an indicative sample is provided below: Practitioners encouraged estimating energy needs from lean body mass measures but recommended that caution should be exerted when using predictive equations with rugby players. Recording dietary intakes should be done so with caution with additional supporting quality control measures adopted. High protein intakes (>2 g. kg. BM-1 ) are deemed acceptable by practitioners provided other nutrient consumption is not compromised. There appears to be varied practices in carbohydrate consumption across playing positions, and often players may sacrifice carbohydrate intake for body composition goals. Body composition is a primary driver for the rugby player, however influencing factors of vanity and body image play a large role which may compromise them as a rugby player. Social media has increased interest in food and can be used as an educational tool, however sometimes players receive inappropriate information. A trackable system of supplement use should be in place and any supplementation protocols implemented should have an evidence basis. Practitioners should always have an alternative food strategy to any supplements used. All supplement strategies should be assessed throughout the season for psychological and physiological variation and it is important to be aware of the large influence senior players have over young players regarding supplement use. Finally, a key message was that even in a team sport setting it is important to acknowledge that responses to nutrition and training are highly individual and variable. Despite obtaining much agreement in appropriate practices, a relatively high level of disparity in opinion occurred in the areas of fat intake, recovery and nutrition for supporting illness. Discussion: While current research in rugby nutrition is developing, this Delphi Poll study presents a unique approach to conducting research in the field of applied sport and exercise nutrition. These statements will facilitate expert practitioners in moving towards a consensus regarding optimum nutritional strategies for the rugby player. This research can be utilised by new or developing practitioners, while an empirical evidence base is being established. Conclusion: As well as providing a consensus, the present study highlights areas where practitioners should exercise caution regarding recommendations, as more research is required to help inform their practice. References: 1. Hasson F, Keeney, S, McKenna, H. Research guidelines for the Delphi survey technique, Journal of Advanced Nursing 2000; 32 1008-1015.

Total energy expenditure (TEE) has been quantified in elite senior rugby league (RL) and rugby union (RU) players using multiple measures, with criterion measures lacking in RU and academy players. Robust measures of TEE are required as prediction equations used to estimate energy requirements are often unsuitable for athletes. This study quantified TEE of 27 elite male English academy (U16 and U20) and senior (U24) RL and RU players during a 14-day in-season period using doubly labelled water (DLW). Resting metabolic rate (RMR), using indirect calorimetry, and physical activity level (PAL) was also measured (TEE:RMR). Predicted TEE, determined by published equations, was compared to measured TEE by age group. Differences in TEE (RL, 4369 ± 979; RU, 4365 ± 1122; U16, 4010 ± 744; U20, 4414 ± 688; U24, 4761 ± 1523 Kcal.day-1) and PAL (overall mean 2.0 ± 0.4) were unclear. RMR was very likely greater for RL (2366 ± 296 Kcal.day-1) than RU players (2123 ± 269 Kcal.day-1). Relative RMR for U16, U20 and U24 (27 ± 4, 23 ± 3 and 26 ± 5 Kcal.Kg-1.day-1) was very likely greater for U20 than U24 players. Differences in TEE estimated by the Schofield, Cunningham and Harris-Benedict equations compared with DLW were unclear, likely and unclear for U16 (187 ± 614; -489 ± 564 and -90 ± 579 Kcal.day-1), likely, very likely and likely for U20 (-449 ± 698; -785 ± 650 and -452 ± 684 Kcal.day-1) and all unclear for U24 players (-428 ± 1292; -605 ± 1493 and -461 ± 1314 Kcal.day-1). Due to large variability between individuals, negligible differences in TEE were observed by code, and ~350-400 Kcal.day-1 differences between consecutive age groups were unclear. Differences in RMR may be due to training exposure and match play. The remaining components of TEE (i.e. thermic effect of feeding and activity thermogenesis) may reflect the differences in contact demands between codes, as RU players typically engage in more static exertions than RL players during match play. Prediction equations are currently insufficient to differentiate between individual variability in TEE. The importance of practitioners providing individual support for the elite rugby player is highlighted. Finally, the TEE measured in this study using the gold standard DLW method can be used as reference data for elite rugby players of different codes and ages, during an in-season training period.

OBJECTIVE: To examine the effects of consuming a galactose carbohydrate (CHO) drink on substrate oxidation, postexercise satiety, and subsequent energy intake. METHODS: Nine recreationally active eumenorrheic females undertook 3 trials, each consisting of running for 60 minutes at 65% VO2peak followed immediately by a 90-minute rest period. Prior to (300 ml) and at 15-minute intervals during exercise (150 ml), participants consumed either a glucose (GLU: GI 89) or galactose (GAL: GI 20) drink, each of which contained 45 g of CHO, or an artificially sweetened placebo (PLA). Following the rest period, participants were provided with an ad libitum test lunch and asked to record food intake for the remainder of the day. RESULTS: Plasma glucose was significantly greater throughout exercise and rest following the GLU trial compared with the GAL and PLA trials (P < 0.05); however there were no differences in CHO oxidation. Hunger was significantly lower (P < 0.05) throughout the GAL compared to the GLU and PLA trials. There were no significant differences between trials for energy intake during the postexercise meal. Overall net energy balance for the 24 hours was negative in both the GAL (-162 ± 115 kcal; P < 0.05 vs GLU) and PLA trials (-49 ± 160 kcal). CONCLUSIONS: Results demonstrate that ingesting a solution containing GAL before and during exercise can positively impact postexercise satiety and energy balance throughout the day, compared to a more readily available and widely consumed form of CHO. Despite this, there appears to be no apparent benefit in consuming a CHO beverage on fuel utilization for this moderate exercise intensity and duration.

The aim was to determine if the implementation of a nutrition education program can improve the nutritional knowledge and dietary practice of male academy rugby union players. On obtaining institutional ethics approval, 16 players were recruited and split by age category. Both an under 16 (U16) group N=9 (17 ± 1 y) and under 19 (U19) group N=7 (19 ± 0 y) participated in an eight session program. The sessions informed participants on the principles of sports nutrition and met individual nutrition needs. Both groups completed a nutrition knowledge questionnaire and a 7 day diet diary pre and post program delivery. Dietary analysis was conducted and adequacy of intake was assessed by comparison with calculated recommended values. Delta values were used to assess the difference between required and actual intake values for different dietary components. Results show increases in nutrition knowledge scores for all participants, 31.5–37.2 (p=0.000). There was a strong positive correlation between age and nutrition knowledge scores both pre (r=0.518, n=18, p<0.027) and post (r=0.472, n=18, p<0.48). There was improvement in energy and carbohydrate intake within the U19 group, t (6) = −3.837, p<0.009, t (6) = −4.653, p<0.003 respectively. Although not significant, improvements in fluid intake were seen as average intakes increased by 1.72 l (U19) and 0.68 l (U18). The main finding was improvements in nutrition knowledge following a nutrition education program. A link between age and knowledge was highlighted. There were improvements in dietary intake whereby participants more closely met recommended intakes. For the U19, improvements were statistically significant, but for the U18 who are not solely responsible for their dietary intake improvements were less evident. Further research into the barriers facing younger athletes in achieving adequate dietary intake is warranted.

Carbohydrate mouth rinsing can improve endurance exercise performance and is most ergogenic when exercise is completed in the fasted state. This strategy may also be beneficial to increase exercise capacity and the energy deficit achieved during moderate intensity exercise relevant to weight control when performed after an overnight fast. Eighteen healthy men (mean(SD); age 23(4)years, body mass index 23.1(2.4)kg.m-2 ) completed a familiarisation trial and three experimental trials. After an overnight fast, participants performed 60-minutes of treadmill walking at a speed that equated to a rating of perceived exertion of 13 (“fairly hard”). Participants manually adjusted the treadmill speed to maintain this exertion. Mouth rinses for the experimental trials contained either a 6.4% maltodextrin solution with sweetener (CHO), a taste-matched placebo (PLA) or water (WAT). Appetite ratings were collected using visual analogue scales and exercise energy expenditure and substrate oxidation were calculated from online gas analysis. Increased walking distance during CHO and PLA induced greater energy expenditure compared with WAT (mean difference (90% CI); 79(60)kJ; P=0.035; d=0.24 and 90(63)kJ; P=0.024; d=0.27, respectively). Appetite area under the curve was lower in CHO and PLA than WAT (8(6)mm; P=0.042; d=0.43 and 6(8)mm; P=0.201; d=0.32, respectively). Carbohydrate oxidation was higher in CHO than PLA and WAT (7.3(6.7)g; P=0.078; d=0.47 and 10.1(6.5)g; P=0.015; d=0.81, respectively). This study provides novel evidence that mouth rinsing with a sweetened solution may promote a greater energy deficit during moderate exertion walking exercise by increasing energy expenditure and decreasing appetite. A placebo effect may have contributed to these benefits.

Background. In this Position Statement, the International Society of Sports Nutrition (ISSN) provides an objective and critical review of the literature pertinent to nutritional considerations for training and racing in single-stage ultra-marathon. Recommendations for Training. i) Ultra-marathon runners should aim to meet the caloric demands of training by following an individualized and periodized strategy, comprising a varied, food-first approach; ii) Athletes should plan and implement their nutrition strategy with sufficient time to permit adaptations that enhance fat oxidative capacity; iii) The evidence overwhelmingly supports the inclusion of a moderate-to-high carbohydrate diet (i.e., ~60% of energy intake, 5 – 8 g⸱kg−1·d−1) to mitigate the negative effects of chronic, training-induced glycogen depletion; iv) Limiting carbohydrate intake before selected low-intensity sessions, and/or moderating daily carbohydrate intake, may enhance mitochondrial function and fat oxidative capacity. Nevertheless, this approach may compromise performance during high-intensity efforts; v) Protein intakes of ~1.6 g·kg−1·d−1 are necessary to maintain lean mass and support recovery from training, but amounts up to 2.5 g⸱kg−1·d−1 may be warranted during demanding training when calorie requirements are greater; Recommendations for Racing. vi) To attenuate caloric deficits, runners should aim to consume 150 - 400 kcal⸱h−1 (carbohydrate, 30 – 50 g⸱h−1; protein, 5 – 10 g⸱h−1) from a variety of calorie-dense foods. Consideration must be given to food palatability, individual tolerance, and the increased preference for savory foods in longer races; vii) Fluid volumes of 450 – 750 mL⸱h−1 (~150 – 250 mL every 20 min) are recommended during racing. To minimize the likelihood of hyponatraemia, electrolytes (mainly sodium) may be needed in concentrations greater than that provided by most commercial products (i.e., >575 mg·L−1 sodium). Fluid and electrolyte requirements will be elevated when running in hot and/or humid conditions; viii) Evidence supports progressive gut-training and/or low-FODMAP diets (fermentable oligosaccharide, disaccharide, monosaccharide and polyol) to alleviate symptoms of gastrointestinal distress during racing; ix) The evidence in support of ketogenic diets and/or ketone esters to improve ultra-marathon performance is lacking, with further research warranted; x) Evidence supports the strategic use of caffeine to sustain performance in the latter stages of racing, particularly when sleep deprivation may compromise athlete safety.

Introduction Acute exposure to very high altitude (>3500m) is associated with a significant suppression of appetite and energy intake, which may contribute to losses of lean mass and functional capacity. The reasons for this appetite suppression are unclear and it is unknown whether this will occur during acute exposure to moderate altitudes. This study examined the effects of exercise on appetite, appetite hormones and energy intake at moderate and very high altitudes. Methods Twelve healthy males (mean±SD; age 30±9years, body mass index 24±3kg.m-2) completed three, 305-minute experimental trials at a simulated altitude of 0m (sea level: SL), 2150m (~15.8% O2) and 4300m (~11.7% O2) in a normobaric chamber. The trials were randomised using a counterbalanced Latin Square design. Participants arrived at the laboratory after a 12h fast, entering the chamber at 8am. A standardised breakfast was consumed inside the chamber at 1h. One hour after breakfast, participants performed a 60-minute treadmill walk at 50% of altitude specific VO2max. An ad-libitum buffet meal was consumed 1.5h after exercise. Composite appetite score (CAS) ([hunger+prospective food consumption+(100–fullness)+(100–satisfaction)]/4), acylated ghrelin (AG), glucagon like peptide-1 (GLP1) and insulin were measured throughout. Results During the resting period prior to exercise there were no significant differences in any variables between conditions. During exercise, area under the curve (AUC) for CAS was significantly lower at 4,300m (33±5mm.h-1) compared with 2150m (44±5mm.h-1; p=0.024) but not compared with SL (42±4mm.h-1; p>0.05). In the post-exercise period, AUC for CAS was significantly lower at 4300m (40±19mm.h-1) compared with SL (55±15mm.h-1; p=0.004) and 2150m (60±14mm.h-1; p<0.001). During exercise, AUC for AG was significantly lower at 4300m (48±23pg.mL-1.h-1) compared with SL (69±27pg.mL-1.h-1; p=0.005) and 2150m (67±31pg.mL-1.h-1; p=0.01). During the post exercise period AUC for AG was significantly lower at 4,300m (49±31pg.mL-1.h-1) compared with SL (116±49pg.mL-1.h-1; p<0.001) and 2150m (111±62pg.mL-1.h-1; p=0.002). There were no differences in GLP1 or insulin between conditions. Mean energy intake was significantly lower at 4300m (3728±3179kJ) compared with SL (7358±1789kJ; p=0.007) and 2150m (7390±1226kJ; p=0.004). There was no difference in CAS, AG or energy intake between SL and 2150m. Discussion This study suggests that altitude-induced anorexia and a subsequent reduction in energy intake occurs with acute exposure to very high but not moderate altitudes. This effect may be explained by reduced concentrations of AG at very high altitudes. Further research should aim to identify methods of reducing appetite suppression at altitude.

Mouth-rinsing with carbohydrate solutions during cycling time trials results in performance enhancements, however the majority of studies have utilised ∼6% carbohydrate solutions. Therefore, the purpose of this study was to compare the effectiveness of mouth-rinsing with 4%, 6%, and 8% carbohydrate (CHO) solutions on 1-h simulated cycling time trial performance. On four occasions, seven trained male cyclists completed at the postprandial period, a set amount of work as fast as possible in a randomised, counterbalanced order. The subjects mouth rinsed for 5-s, upon completion of each 12.5% of the trial, with 25 mL of a non-CHO placebo, 4%, 6%, and 8% CHO solutions. No additional fluids were consumed during the time trial. Heart rate (HR), ratings of perceived exertion (RPE), thirst (TH) and subjective feelings (SF) were recorded after each rinse. Further, blood samples were drawn every 25% of the trial to measure blood glucose (BG) and blood lactate (BG) concentrations, whilst whole body carbohydrate oxidation was monitored continuously. Time to completion was not significant between conditions with the placebo, 4%, 6%, and 8% conditions completing the trials in 62.0 ± 3.0, 62.8 ± 4.0, 63.4 ± 3.4, and 63 ±4.0 minutes respectively. There were no significant differences between conditions in any of the variables mentioned above however significant time effects were observed for HR, RPE, TH, and SF. Post-hoc analysis showed that TH and SF of subjects in the CHO conditions but not in the placebo were significantly increased by completion of the time trial. In conclusion, mouth-rinsing with CHO solutions did not impact 1-h cycling performance in the postprandial period and in the absence of fluid intake. Our findings suggest that there is scope for further research to explore the activation regions of the brain and whether they are receptive to CHO dose, before specific recommendations for athletic populations are established. Consequently mouth-rinsing as a practical strategy for coaches and athletes is questionable under specific conditions and should be carefully considered before its inclusion. The emphasis should be focused on appropriate dietary and fluid strategies during training and competition.

Background: Dietary behaviours of adolescence are concerning, and this may impact long-term well-being. Aim: This study examined the socio-ecological determinants of dietary behaviours in a national prospective cohort study of English adolescents. Methods: Latent class analysis was used to identify the typologies of eight dietary behaviours: fruit, vegetable, breakfast, sugar-sweetened beverages, artificial-sweetened beverages, fast-food, bread, and milk from 7402 adolescents aged 13-15 years (mean 13.8 ± 0.45 years) (50.3% female and 71.3% white ethnicity) participating in the U.K. Millennium Cohort Study (sixth survey). Multinomial logistic regression and path analysis predicted associations between personal characteristics, individual, influential others, social environment and physical environment determinants and three distinct diet typologies: (1) healthy, (2) less-healthy and (3) mixed, (reference category = mixed). Results: Within Path analysis, the magnitudes of coefficients were small to moderate suggesting a relatively weak relationship between the variables. Model 1 reported adolescents within the less-healthy compared to mixed typology had lower levels of physical activity (β = 0.074, 95% CI = -0.115, -0.033), and have siblings (β = 0.246, 95% CI = 0.105, 0.387). Model 2 reported adolescents within the healthy compared to mixed typology had lower screen time (β = 0.104, 95% CI = 0.067, 0.141), and lower social media usage (β = 0.035, 95% CI = 0.024, 0.046). Conclusion: This study highlights the importance of considering multiple dietary determinants. These findings are likely to be useful in supporting the development of multi-faceted interventions. They emphasise the need to move away from investigating silo behaviours on individual diet components and a step towards more systems thinking to improve adolescent eating behaviours.

There is a developing base of research assessing hormonal status in rugby players as a means to monitor training and performance, however to date no research has investigated the impact of dietary intake on immunity. The objectives of the study were to monitor immune responses, as well as assess dietary intake, body composition and performance of elite rugby union players. Following ethics approval, nine players (height 185.8±6.2cm, age 28.0±3.4yrs) were assessed at the start and end of a 4-week pre-season training period for dietary intake (4-day food diary), body composition (sum of 8 [Σ8] skinfold sites), one repetition maximum (1RM) strength (bench press [BP] and prone row [PR]) and endurance (1200m run). Saliva immunoglobulin A (sIgA) measures were taken at the start and end of each week (~8.30am). Mean energy intakes were 12145.9±3772.3kJ (week 1) and 12419.7±2385.5kJ (week 4). During both weeks of dietary assessment protein and carbohydrate consumption was 2.3±0.7 and 2.7±1.1g.kg.BM-1.d-1 respectively. There was a 32%, 36% and 32% contribution from protein, carbohydrate and fat to energy intake. Despite relatively low energy consumption (approximately 45% below recommendations), there was only a 0.7±2.4kg reduction in body mass (103.7±13.7 to 103±13.4kg) and a 12±2% reduction in for Σ8 skinfolds from week 1 to week 4 (106.7±44.3 to 94.17±43.6mm). Mean sIgA over the training period was 47.9±ug.min-1, with a small intra-player variability observed throughout the 4-week preseason training period (CV 5%). sIgA was strongly correlated with fat (r=0.68) and saturated fat intake (r=0.62). sIgA was also moderately correlated with protein intake (r=0.40), Σ8 skinfolds (r=0.39) and endomorphy (r=0.43). Conversely, strong and moderate negative correlations occurred between sIgA and mesomorphy (r=-0.51), and sIgA and ectomorphy (r=-0.49). Significant improvements (P<0.05) were observed for 1RM in BP (4.0 ± 4.93 kg) and 1200m (23 ± 5.27 sec) with 1200m times strongly correlating with sIgA (r=0.56). Conversely there were moderate negative correlations between improvements in strength and sIgA (r=-0.42). In summary, players with a higher dietary fat intake and endomorphic characteristics demonstrated a better immune status than leaner ectomorphic players. Those showing better immune function also produced greater gains in endurance. The negative correlations between strength and sIgA were likely due to enhanced rates of catabolism as a result of resistance training. The pre-season training period elicited improvements in body composition despite inadequate dietary intake when compared to guidelines, highlighting the potential error of applying the recommended nutrient intake guidelines to an elite rugby union population.

Exposure to hypoxia appears to depress appetite and energy intake, however the mechanisms are not fully understood. The aim of this review was to determine the magnitude of changes in hunger and energy intake in hypoxic compared with normoxic environments, and establish any alterations in appetite-related hormone concentrations. PubMed and The Cochrane Library as well as MEDLINE, SPORTDiscus, PsycINFO and CINAHL, via EBSCOhost, were searched through 1st April 2017 for studies that evaluated hunger, energy intake and/or appetite-related hormones in normoxia and during hypoxic exposure in a within-measures design. A total of 28 studies (comprising 54 fasted and 22 postprandial comparisons) were included. A random-effects meta-analysis was performed to establish standardised mean difference (SMD) with 95% confidence intervals. Hypoxic exposure resulted in a trivial but significant decrease in postprandial hunger scores (SMD: -0.15, 95% CI: -0.29 to -0.01; n = 14; p = 0.043) and a moderate decrease in energy intake (SMD: -0.50, 95% CI: -0.85 to -0.15; n = 8; p = 0.006). Hypoxic exposure resulted in a decrease (albeit trivial) in postprandial acylated ghrelin concentrations (SMD: -0.16, 95% CI: -0.25 to -0.08; n = 7; p < 0.0005), and a moderate increase in fasted insulin concentrations (SMD: 0.41, 95% CI: 0.17 to 0.65; n = 34; p = 0.001). Meta-regression revealed a decrease in postprandial acylated ghrelin concentrations (p = 0.010) and an increase in fasted insulin concentrations (p = 0.020) as hypoxic severity increased. Hypoxic exposure reduces hunger and energy intake, which may be mediated by decreased circulating concentrations of acylated ghrelin and elevated insulin concentrations. PROSPERO registration number: CRD42015017231.

Acute exposure to high altitude (>3500m) is associated with marked changes in appetite regulation and substrate oxidation but the effects of lower altitudes are unclear. This study examined appetite, gut hormone, energy intake and substrate oxidation responses to breakfast ingestion and exercise at simulated moderate and severe altitudes compared with sea-level. Twelve healthy males (mean±SD; age 30±9years, body mass index 24.4±2.7kg.m-2) completed in a randomised crossover order three, 305 minute experimental trials at a simulated altitude of 0m, 2150m (~15.8% O2) and 4300m (~11.7% O2) in a normobaric chamber. Participants entered the chamber at 8am following a 12h fast. A standardised breakfast was consumed inside the chamber at 1h. One hour after breakfast, participants performed a 60 minute treadmill walk at 50% of relative V̇O2max. An ad-libitum buffet meal was consumed 1.5h after exercise. Blood samples were collected prior to altitude exposure and at 60, 135, 195, 240 and 285 minutes. No trial based differences were observed in any appetite related measure before exercise. Post-exercise area under the curve values for acylated ghrelin, pancreatic polypeptide and composite appetite score were lower (all P<0.05) at 4300m compared with sea-level and 2150m. There were no differences in glucagon-like peptide-1 between conditions (P=0.895). Mean energy intake was lower at 4300m (3728±3179kJ) compared with sea-level (7358±1789kJ; P=0.007) and 2150m (7390±1226kJ; P=0.004). Proportional reliance on carbohydrate as a fuel was higher (P=0.01) before breakfast but lower during (P=0.02) and after exercise (P=0.01) at 4300m compared with sea-level. This study suggests that altitude-induced anorexia and a subsequent reduction in energy intake occurs after exercise during exposure to severe but not moderate simulated altitude. Acylated ghrelin concentrations may contribute to this effect.

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.

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 It is well established that acute exposure to very high altitude (>3500m) is associated with a suppression of appetite, acylated ghrelin and energy intake. Ghrelin is post-translationally modified with a medium chain fatty acid and this acylation is necessary for ghrelin to exert its orexigenic effects. This novel study investigated the effects of a high-fat (HF) breakfast rich in medium chain fatty acids versus a high-carbohydrate (HC) breakfast on appetite, ghrelin constituents and energy intake at 4300m simulated altitude. Methods Twelve healthy males (mean (SD); age 26 (8) years, body mass index 23.9 (2.7) kg·m-2) completed two, 305-minute experimental trials at a simulated altitude of 4300m (~11.7% O2) in a normobaric chamber. Trials were conducted in a randomised, single blind, counter-balanced fashion. After an overnight fast, participants entered the chamber and rested until receiving breakfast at 1h. Participants consumed either an isocaloric HF (60% fat, 25% carbohydrate and 15% protein) or HC (60% carbohydrate, 25% fat and 15% protein) breakfast. One hour after breakfast, participants performed a 60-minute treadmill walk at 50% of relative V̇O2max. An ad-libitum buffet meal was consumed 1.5h after exercise. Composite appetite score (CAS) as well as acylated (AG) and de-acylated ghrelin (DG) were measured throughout. Results At baseline and during the resting period prior to exercise there were no significant differences in any variables between conditions (all P≥0.137). During exercise, area under the curve (AUC) for CAS was significantly higher following the HF breakfast (39 (12) mm·h-1) compared with the HC breakfast (30 (17) mm·h-1, P=0.036). Similarly, AUC for AG was significantly higher during exercise following the HF breakfast (152 (180) pg·mL-1·h-1) compared with the HC breakfast (101 (106) pg·mL-1·h-1, P=0.048). During the post-exercise period there was no significant difference in CAS (P=0.356) or AG (P=0.229) between conditions. No differences were observed during any time period in DG (all P≥0.207). Energy intake at the buffet did not significantly differ between conditions (P=0.384). Discussion This study suggests that, in comparison with a HC breakfast, a HF breakfast rich in medium chain fatty acids can attenuate appetite suppression during exercise at 4300m simulated altitude. However, this did not translate into increased ad-libitum energy intake when food was provided 90 minutes after exercise. It would be beneficial for further research to establish whether a prolonged HF diet can promote a positive energy balance at altitude.

High-altitude exposure induces a negative energy balance by increasing resting energy expenditure and decreasing energy intake. This diminished energy intake is likely caused by altitude-induced anorexia and can have detrimental effects for those travelling to high-altitude. We aimed to investigate whether altering the macronutrient composition of breakfast could attenuate altitude-induced anorexia and augment energy intake at high-altitude. Twelve healthy men (aged 26 (8) years, body mass index 23.9 (2.7) kg·m(-2)) completed two, 305min experimental trials at 4300m simulated altitude (~11.7% O2). After an overnight fast, participants entered a normobaric hypoxic chamber and rested for one hour, before receiving either a high fat (HF; 60% fat, 25% carbohydrate) or an isocaloric high carbohydrate (HC; 60% carbohydrate, 25% fat) breakfast. One hour after breakfast, participants performed 60min of treadmill walking at 50% of relative V̇O2max. An ad-libitum buffet meal was consumed 1h 30min after exercise. Appetite perceptions, blood samples and substrate oxidation rates were measured throughout. A significantly higher area under the curve for composite appetite score was observed during exercise in HF (40 (12) mm·h(-1)) compared with HC (30 (17) mm·h(-1), P=0.036). During exercise, lower insulin concentrations (P=0.013) and elevated acylated ghrelin concentrations (P=0.048) were observed in HF compared with HC. After exercise there was no significant difference in composite appetite score (P=0.356), acylated ghrelin (P=0.229) or insulin (P=0.513) between conditions. Energy intake at the buffet did not significantly differ between conditions (P=0.384). A HF breakfast attenuated appetite suppression during exercise at 4300m simulated altitude, however ad-libitum energy intake did not increase.

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.

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.

Age-related sarcopenia is a syndrome characterised by progressive decline in skeletal muscle mass and strength (von Haehling, Morley, & Anker, 2010). The European Working Group on Sarcopenia in Older People recommends the measurement of muscle mass and function as means of diagnosing sarcopenia (Cruz-Jentoft et al., 2010) since sole focus on measurement of muscle mass may be of limited value. The age-associated loss of muscle strength (Dynapenia) cannot be only explained by reductions in muscle size since reductions in strength are more rapid than reductions in muscle (Clark & Manini, 2012). Cawthon et al. (2014) developed cut points for appendicular lean mass (ALM) that would identify individuals with clinically significant weakness taking into account both ALM and strength. Since sarcopenia is a multifaceted syndrome with potentially modifiable factors such as dietary intakes, the aim of this pilot study was to explore the interrelationships between dietary intakes, ALM, and strength. Twenty-five healthy older adults including both female (n=15, age: 68.8 ± 2.9 years) and male (n =10, age 69.5 ± 2.5 years) participants completed a 7-day diet diary before having their handgrip strength and body composition (dual energy X-ray absorptiometry) measured. Males with ALM<19.75 kg and females with ALM<15.02 kg were defined as having low lean muscle mass, whilst cut points of <30 kg and <20 kg (Campbell & Vallis, 2014) were used to identify males and females with low strength. Participants received guidance on recording food and drink by household measures. Energy expenditure was calculated using the World Health Organization/Food and Agriculture Organization equation (Frankenfield, Roth-Yousey, & Compher, 2005) for resting energy expenditure and an activity factor of 1.5. Forty percent (40%) of the females displayed low muscle strength while their male counterparts were all above the 30 kg cut point. ALM was 25.6±3.7 and 15.9±1.7 kg for males and females respectively. Twenty-seven percent (27%) of the females were below the cut point for low lean mass whilst males were all above the equivalent cut point. Energy intake (EI) was 1753±366 kcal for males and 1376±270 kcal for females corresponding to an EI deficit of 27.8±21.7 % and 27.7±6 % for males and females respectively. EI was significantly (P<0.05) lower than recommended EI. Protein intake was 0.97±0.3 g·kg·d-1 for the males and 0.95±0.2 g·kg·d-1 for the females representing 18.8±3.1 and 17.8±2.4 % of EI for males and females respectively. Our findings suggest that females in early retirement years are at greater risk of sarcopenia and dynapenia than their male counterparts. Inadequate energy intake and protein consumption which was below current research led recommendations of 20 % suggest that females may benefit from dietary interventions that would address energy and protein deficits. References Campbell, T. M., & Vallis, L. A. (2014). Predicting fat-free mass index and sarcopenia in assisted-living older adults. Age (Dordr), 36(4), 9674. doi: 10.1007/s11357-014-9674-8 Cawthon, P. M., Peters, K. W., Shardell, M. D., McLean, R. R., Dam, T.-T. L., Kenny, A. M., . . . Guralnik, J. M. (2014). Cutpoints for low appendicular lean mass that identify older adults with clinically significant weakness. The Journals of Gerontology Series A: Biological Sciences and Medical Sciences, 69(5), 567-575. Clark, B. C., & Manini, T. M. (2012). What is dynapenia? Nutrition, 28(5), 495-503. doi: 10.1016/j.nut.2011.12.002 Cruz-Jentoft, A. J., Baeyens, J. P., Bauer, J. M., Boirie, Y., Cederholm, T., Landi, F., . . . European Working Group on Sarcopenia in Older, P. (2010). Sarcopenia: European consensus on definition and diagnosis: Report of the European Working Group on Sarcopenia in Older People. Age Ageing, 39(4), 412-423. doi: 10.1093/ageing/afq034 Frankenfield, D., Roth-Yousey, L., & Compher, C. (2005). Comparison of predictive equations for resting metabolic rate in healthy nonobese and obese adults: a systematic review. J Am Diet Assoc, 105(5), 775-789. doi: 10.1016/j.jada.2005.02.005 Morley, J. E. (2008). Sarcopenia: diagnosis and treatment. J Nutr Health Aging, 12(7), 452-456. von Haehling, S., Morley, J. E., & Anker, S. D. (2010). An overview of sarcopenia: facts and numbers on prevalence and clinical impact. J Cachexia Sarcopenia Muscle, 1(2), 129-133. doi: 10.1007/s13539-010-0014-2

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.

Deficiencies in protein and energy intakes are partly responsible for age-related sarcopenia. We investigated the effects of supplements matched in essential amino acid (EAA) content (7.5 g) on energy intake and appetite. Ten women aged 69.2 ± 2.7 years, completed three trials in a randomised, crossover design. Composite appetite scores, peptide-YY (PYY), and insulin responses to a 200 ml whey protein isolate (WP, 275 kJ), a 50 ml EAA gel (GEL, 478 kJ) or nothing as the control condition (CON) were investigated over one hour, followed by an ad libitum breakfast. Energy intake at breakfast (CON 1957 ± 713, WP 1413 ± 623, GEL 1963 ± 611 kJ) was higher in CON and GEL than in WP (both P = 0.006). After accounting for supplement energy content, energy intake in GEL was higher than in CON (P = 0.0006) and WP (P = 0.0008). Time-averaged area under the curve for composite appetite scores (CON 74 ± 20, WP 50 ± 22, GEL 60 ± 16 mm) was higher in CON than WP (P = 0.015). Time-averaged area under the curve for PYY (CON 87 ± 13, WP 119 ± 27, GEL 97 ± 22 pg·mL-1) was higher in WP than CON (P = 0.009) and GEL (P = 0.012). In conclusion, supplementation with WP facilitated an increase in protein intake, whereas supplementation with GEL increases in both energy and protein intakes, when consumed before an ad libitum breakfast. Such findings, highlight potential gel-based EAA supplementation intake for addressing age-related sarcopenia.

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.

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.

The consumption frequency and portion size of discretionary snacks are thought to contribute to a greater food intake and risk of overweight or obesity in the developed world but evidence from epidemiological studies is inconclusive. To investigate this, we systematically evaluated evidence on the effects of discretionary snack consumption on weight status, energy intake, and diet quality. Articles involving discretionary snacks reported against the outcome measures of any primary, peer-reviewed study using human participants from free-living conditions for all age groups were included. A total of 14,780 titles were identified and 40 eligible publications were identified. Three key outcomes were reported: weight status (n = 35), energy intake (n = 11), and diet quality (n = 3). Increased discretionary snack consumption may contribute modestly to energy intake, however, there is a lack of consistent associations with increased weight/BMI. Although cross-sectional analyses offered conflicting findings, longitudinal studies in adults showed a consistent positive relationship between discretionary snack intake and increasing weight or body mass index. Given that experimental findings suggest reducing the size of discretionary snacks could lead to decreased consumption and subsequent energy intake, food policy makers and manufacturers may find it valuable to consider altering the portion and/or packaging size of discretionary snacks.

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.

Introduction Acute exposure to very high altitude (>3500m) is associated with a suppression of appetite, acylated ghrelin (AG) and energy intake. Appetite suppression at altitude is likely caused by the reduction in arterial oxygen saturation (SpO2), consequent to the low oxygen tensions present at altitude. Beetroot juice (BRJ) has shown to minimise the altitude-related reductions in SpO2 and may therefore provide relief of altitude-induced suppression of AG and appetite. The present study investigated the effects of BRJ supplementation on appetite, AG and energy intake at 4300m simulated altitude. Methods Ten healthy males (mean(SD); age 24(7) years, body mass index 25(3)kg·m-2) completed two 6h 30mins experimental trials in normobaric hypoxia, simulating an altitude of 4300m (~11.7% FiO2). Trials were conducted in a randomised, double blind, counter-balanced fashion. After an overnight fast, participants arrived at the laboratory and completed baseline measures. Following cannulation, participants consumed a porridge breakfast accompanied by 140ml concentrated BRJ (Beet It, James White Ltd., UK) or placebo. Participants entered the hypoxic chamber 90mins after breakfast, where they rested for 2h 30mins. Participants then completed a 60min treadmill walk at 10% gradient and 50% of relative V̇O2max, whilst carrying a 10kg rucksack. After exercise, participants consumed a snack and 70ml concentrated BRJ or placebo. Participants then rested inside the chamber until 6h 30mins. After leaving the chamber, the participants were given an ad-libitum homogenous pasta meal. Fractional exhaled nitric oxide (FeNO) provided a marker of nitric oxide bioavailability. Composite appetite score (CAS) and AG were measured throughout; results are presented for four area under the curve (AUC) periods: pre-hypoxic, hypoxic rest, exercise and post-exercise. Results At baseline there were no differences in any variables between conditions (P≥0.382). There was no significant difference in FeNO between conditions upon entry to the chamber (P=0.110), however FeNO was significantly elevated in BRJ immediately prior to exercise, compared with placebo (P=0.034). There were no differences between conditions during any of the AUC periods for SpO2 (P≥0.746), AG (P≥0.231), or CAS (P≥0.730). Energy intake at the ad-libitum buffet meal did not differ between BRJ (3542±1306kJ) and placebo (3980±1342kJ; P=0.270). Discussion This study suggests that acute BRJ supplementation has no effect on appetite, AG, or energy intake at 4300m simulated altitude. However, other methodological approaches which may elevate SpO2, such as chronic BRJ loading, require further investigation.

Purpose Circulating acylated ghrelin concentrations are associated with altitude-induced anorexia in laboratory environments, but have never been measured at terrestrial altitude. This study examined time course changes in appetite, energy intake, body composition, and ghrelin constituents during a high-altitude trek. Methods Twelve participants [age: 28(4) years, BMI 23.0(2.1) kg m−2] completed a 14-day trek in the Himalayas. Energy intake, appetite perceptions, body composition, and circulating acylated, des-acylated, and total ghrelin concentrations were assessed at baseline (113 m, 12 days prior to departure) and at three fixed research camps during the trek (3619 m, day 7; 4600 m, day 10; 5140 m, day 12). Results Relative to baseline, energy intake was lower at 3619 m (P = 0.038) and 5140 m (P = 0.016) and tended to be lower at 4600 m (P = 0.056). Appetite perceptions were lower at 5140 m (P = 0.027) compared with baseline. Acylated ghrelin concentrations were lower at 3619 m (P = 0.046) and 4600 m (P = 0.038), and tended to be lower at 5140 m (P = 0.070), compared with baseline. Des-acylated ghrelin concentrations did not significantly change during the trek (P = 0.177). Total ghrelin concentrations decreased from baseline to 4600 m (P = 0.045). Skinfold thickness was lower at all points during the trek compared with baseline (P ≤ 0.001) and calf girth decreased incrementally during the trek (P = 0.010). Conclusions Changes in plasma acylated and total ghrelin concentrations may contribute to the suppression of appetite and energy intake at altitude, but differences in the time course of these responses suggest that additional factors are also involved. Interventions are required to maintain appetite and energy balance during trekking at terrestrial altitudes.

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

Abstract

Objective: To evaluate the effect of a high‐protein diet on anthropometry, body composition, subjective appetite, and mood sensations in overweight and obese children attending a residential weight‐loss camp.

Research Methods and Procedures: Children (120; BMI, 33.1 ± 5.5 kg/m2; age, 14.2 ± 1.9 years) were randomly assigned to either a standard or high‐protein diet group (15% vs. 22.5% protein, respectively). All children were assessed at baseline and at the end of the camp for anthropometry, body composition, blood pressure, biochemical variables (n = 27), and subjective appetite and mood sensations (n = 50).

Results: Attendance at the weight‐loss camp resulted in significant improvements in most measures. Campers lost 5.5 ± 2.9 kg in body weight (p < 0.001) and 3.8 ± 5.4 kg in fat mass (p < 0.001) and reduced their BMI standard deviation score by 0.27 ± 0.1 (p < 0.001) and their waist circumference by 6.6 ± 2.8 cm (p < 0.001). Subjective sensations of hunger increased significantly over the camp duration, but no other changes in appetite or mood were observed. There were no significant differences between the two diets on any physical or subjective measures.

Discussion: Weight‐loss camps are effective in assisting children to lose weight and improve on a range of health outcomes, independently of the protein content of the diet. The implications of an increase in hunger associated with weight loss needs to be considered. Further work is warranted to investigate whether higher levels of dietary protein are feasible or effective in longer‐term weight‐loss interventions of this type.

This narrative review examines the mechanisms underlying the development of cardiovascular (CVD) and metabolic diseases (MDs), along with their association with sarcopenia. Furthermore, non-pharmacological interventions to address sarcopenia in patients with these conditions are being suggested. The significance of combined training in managing metabolic disease and secondary sarcopenia in type II diabetes mellitus is emphasized. Additionally, the potential benefits of resistance and aerobic training are being explored. This review emphasises the role of nutrition in addressing sarcopenia in patients with CVD or MDs, focusing on strategies such as optimising protein intake, promoting plant-based protein sources, incorporating antioxidant-rich foods and omega-3 fatty acids, and ensuring sufficient vitamin D levels. Moreover, the potential benefits of targeting gut microbiota through probiotics and prebiotic fibres in sarcopenic individuals are being considered. Multidisciplinary approaches that integrate behavioural science are explored to enhance the uptake and sustainability of behaviour-based sarcopenia interventions. Future research should prioritise high-quality randomized controlled trials to refine exercise and nutritional interventions and investigate the incorporation of behavioural science into routine practices. Ultimately, a comprehensive and multifaceted approach is essential to improve health outcomes, well-being, and quality of life in older adults with sarcopenia and coexisting cardio-vascular and metabolic diseases.