Energy Expenditure of a Male and Female Tennis Player during Association of Tennis Professionals/Women's Tennis Association and Grand Slam Events Measured by Doubly Labeled Water.

METHODS: Doubly labeled water assessed TEE during a 17-d period analyzed by days 1 to 7 (P1) and 7-17 (P2) which included a Women's Tennis Association/Association of Tennis Professionals tournament and culminated at the Wimbledon Championships. Daily training and match loads were assessed using a 10-point Borg scale multiplied by time. Match data were provided by video analysis and player tracking technology. RESULTS: The TEE during P1 for the female player was 3383 kcal·d-1 (63.5 kcal·kg-1) fat-free mass (FFM) with 362 points played over 241 min in three matches covering a distance of 2569 m, with an additional 875 min training. During P2, TEE was 3824 kcal·d-1 (71.7 kcal·kg-1) FFM with 706 points played over 519 min during five matches, covering a distance of 7357 m with an additional 795 min training. The TEE during P1 for the male player was 3712 kcal·d-1 (56.3 kcal·kg-1) FFM with 133 points played over 88 min during one match covering 1125 m, with an additional 795 min training. During P2, TEE was 5520 kcal·d-1 (83.7 kcal·kg-1) FFM with 891 points played over 734 min during five matches, covering 10,043 m, with an additional 350 min training. CONCLUSIONS: This novel data positions elite tennis, played at the highest level, as a highly energetic demanding sport, highlighting that nutritional strategies should ensure sufficient energy availability during competition schedules.

Muscle glycogen utilisation during Rugby match play: Effects of pre-game carbohydrate.

OBJECTIVES: Although the physical demands of Rugby League (RL) match-play are well-known, the fuel sources supporting energy-production are poorly understood. We therefore assessed muscle glycogen utilisation and plasma metabolite responses to RL match-play after a relatively high (HCHO) or relatively low CHO (LCHO) diet. DESIGN: Sixteen (mean±SD age; 18±1 years, body-mass; 88±12kg, height 180±8cm) professional players completed a RL match after 36-h consuming a non-isocaloric high carbohydrate (n=8; 6gkgday-1) or low carbohydrate (n=8; 3gkgday-1) diet. METHODS: Muscle biopsies and blood samples were obtained pre- and post-match, alongside external and internal loads quantified using Global Positioning System technology and heart rate, respectively. Data were analysed using effects sizes ±90% CI and magnitude-based inferences. RESULTS: Differences in pre-match muscle glycogen between high and low carbohydrate conditions (449±51 and 444±81mmolkg-1d.w.) were unclear. High (243±43mmolkg-1d.w.) and low carbohydrate groups (298±130mmolkg-1d.w.) were most and very likely reduced post-match, respectively. For both groups, differences in pre-match NEFA and glycerol were unclear, with a most likely increase in NEFA and glycerol post-match. NEFA was likely lower in the high compared with low carbohydrate group post-match (0.95±0.39mmoll-1 and 1.45±0.51mmoll-1, respectively), whereas differences between the 2 groups for glycerol were unclear (98.1±33.6mmoll-1 and 123.1±39.6mmoll-1) in the high and low carbohydrate groups, respectively. CONCLUSIONS: Professional RL players can utilise ∼40% of their muscle glycogen during a competitive match regardless of their carbohydrate consumption in the preceding 36-h.

Energy intake and expenditure assessed 'in-season' in an elite European rugby union squad.

Rugby union (RU) is a complex high-intensity intermittent collision sport with emphasis placed on players possessing high lean body mass and low body fat. After an 8 to 12-week pre-season focused on physiological adaptations, emphasis shifts towards competitive performance. However, there are no objective data on the physiological demands or energy intake (EI) and energy expenditure (EE) for elite players during this period. Accordingly, in-season training load using global positioning system and session rating of perceived exertion (sRPE), alongside six-day assessments of EE and EI were measured in 44 elite RU players. Mean weekly distance covered was 7827 ± 954 m and 9572 ± 1233 m with a total mean weekly sRPE of 1776 ± 355 and 1523 ± 434 AU for forwards and backs, respectively. Mean weekly EI was 16.6 ± 1.5 and 14.2 ± 1.2 megajoules (MJ) and EE was 15.9 ± 0.5 and 14 ± 0.5 MJ. Mean carbohydrate (CHO) intake was 3.5 ± 0.8 and 3.4 ± 0.7 g.kg(-1) body mass, protein intake was 2.7 ± 0.3 and 2.7 ± 0.5 g.kg(-1) body mass, and fat intake was 1.4 ± 0.2 and 1.4 ± 0.3 g.kg(-1) body mass. All players who completed the food diary self-selected a 'low' CHO 'high' protein diet during the early part of the week, with CHO intake increasing in the days leading up to a match, resulting in the mean EI matching EE. Based on EE and training load data, the EI and composition seems appropriate, although further research is required to evaluate if this diet is optimal for match day performance.

Quantification of training load, energy intake, and physiological adaptations during a rugby preseason: a case study from an elite European rugby union squad.

Rugby Union (RU) is a high-speed collision sport consisting of an intermittent activity profile. Given the extreme physical demands of the sport, significant emphasis is placed on players possessing high lean body mass while minimizing body fat. Anecdotally, the most significant changes in body composition are observed during the preseason; however, there are no objective data on the physiological demands and energy intake during this time. We therefore monitored 45 elite European RU players over the 10-week preseason period by assessing training load using Global Positioning System and session rate of perceived exertion (sRPE) while also assessing changes in anthropometry and physical performance. For forwards and backs, respectively, mean weekly distance covered was 9,774 m (1,404) and 11,585 m (1,810) with a total mean weekly sRPE of 3,398 (335) arbitrary units and 2,944 (410) arbitrary units. Mean daily energy intake was 14.8 MJ (1.9) and 13.3 MJ (1.9), carbohydrate (CHO) intake was 3.3 (0.7) and 4.14 (0.4) g·kg body mass, protein intake was 2.52 (0.3) and 2.59 (0.6) g·kg body mass, and fat intake was 1.0 (0.3) and 0.95 (0.3) g·kg body mass for forwards and backs, respectively. Markers of physical performance (1 repetition maximum strength, speed, and repeated sprint tests) and anthropometry (body fat and estimated lean mass) improved in all players. Interestingly, all players self-selected a "low" CHO "high" protein diet. Based on physiological improvements the training load and energy intake seems appropriate, although further research is required to evaluate if such energy intakes would also be suitable for match day performance.

Vitamin D supplementation does not improve human skeletal muscle contractile properties in insufficient young males.

PURPOSE: Vitamin D may be a regulator of skeletal muscle function, although human trials investigating this hypothesis are limited to predominantly elderly populations. We aimed to assess the effect of oral vitamin D3 in healthy young males upon skeletal muscle function. METHODS: Participants (n = 29) received an oral dose of 10,000 IU day(-1) vitamin D3 (VITD) or a visually identical placebo (PLB) for 3 months. Serum 25[OH]D and intact parathyroid hormone (iPTH) were measured at baseline and at week 4, 8 and 12. Muscle function was assessed in n = 22 participants by isokinetic dynamometry and percutaneous isometric electromyostimulation at baseline and at week 6 and 12. RESULTS: Baseline mean total serum 25[OH]D was 40 ± 17 and 41 ± 20 nmol L(-1) for PLB and VITD, respectively. VITD showed a significant improvement in total 25[OH]D at week 4 (150 ± 31 nmol L(-1)) that remained elevated throughout the trial (P < 0.005). Contrastingly, PLB showed a significant decrease in 25[OH]D at week 12 (25 ± 15 nmol L(-1)) compared with baseline. Despite marked increases in total serum 25[OH]D in VITD and a decrease in PLB, there were no significant changes in any of the muscle function outcome measures at week 6 or 12 for either group (P > 0.05). CONCLUSIONS: Elevating total serum 25[OH]D to concentrations > 120 nmol L(-1) has no effect on skeletal muscle function. We postulate that skeletal muscle function is only perturbed in conditions of severe deficiency (<12.5 nmol L(-1)).