This study examined whether a carbohydrate + casein hydrolysate (CHO+ProH) beverage improved time-trial performance vs. a CHO beverage delivering ~60 g CHO/hr. Markers of muscle disruption and recovery were also assessed. Thirteen male cyclists (VO2peak = 60.8 ± 1.6 ml · kg−1 · min−1) completed 2 computer-simulated 60-km time trials consisting of 3 laps of a 20-km course concluding with a 5-km climb (~5% grade). Participants consumed 200 ml of CHO (6%) or CHO+ProH beverage (6% + 1.8% protein hydrolysate) every 5 km and 500 ml of beverage immediately postexercise. Beverage treatments were administered using a randomly counterbalanced, double-blind design. Plasma creatine phosphokinase (CK) and muscle-soreness ratings were assessed immediately before and 24 hr after cycling. Mean 60-km times were 134.4 ± 4.6 and 135.0 ± 4.0 min for CHO+ProH and CHO beverages, respectively. All time differences between treatments occurred during the final lap, with protein hydrolysate ingestion explaining a significant (p < .05) proportion of betweentrials differences over the final 20 km (44.3 ± 1.6, 45.0 ± 1.6 min) and final 5 km (16.5 ± 0.6, 16.9 ± 0.6 min). Plasma CK levels and muscle-soreness ratings increased significantly after the CHO trial (161 ± 53, 399 ± 175 U/L; 15.8 ± 5.1, 37.6 ± 5.7 mm) but not the CHO+ProH trial (115 ± 21, 262 ± 88 U/L; 20.9 ± 5.3, 32.2 ± 7.1 mm). Late-exercise time-trial performance was enhanced with CHO+ProH beverage ingestion compared with a beverage containing CHO provided at maximal exogenous oxidation rates during exercise. CHO+ProH ingestion also prevented increases in plasma CK and muscle soreness after exercise.
Michael J. Saunders, Rebecca W. Moore, Arie K. Kies, Nicholas D. Luden and Casey A. Pratt
Michal Kumstát, Silvie Rybářová, Andy Thomas and Jan Novotný
The nutritional intake of elite open water swimmers during competition is not well established, and therefore this case study aims to provide new insights by describing the feeding strategies adopted by an elite female swimmer (28 yrs; height; 1.71 m; body mass: 60 kg; body fat: 16.0%) in the FINA open water Grand Prix 2014.Seven events of varying distances (15–88 km) and durations (3–12 hrs) were included. In all events, except one, feeds were provided from support boats. Swimmer and support staff were instructed to track in detail all foods and beverages consumed during the events. Nutritional information was gathered from the packaging and dietary supplements labels and analyzed by nutrition software. Mean carbohydrate (CHO) and protein intake reached 83 ± 5 g·h-1 and 12 ± 8 g·h-1, respectively. Fat intake was neglected (~1 g·h-1). Mean in-race energy intake reached 394 ± 26 kcal·h-1. Dietary supplements in the form of sport beverages and gels, containing multitransportable CHO, provided 40 ± 4 and 49 ± 6% of all CHO energy, respectively. Caffeine (3.6 ± 1.8 mg·kg-1 per event) and sodium (423 ± 16 mg·h-1) were additionally supplemented in all events. It was established that continuous intake of high doses of CHO and sodium and moderate dose of caffeine were an essential part of the feeding strategy for elite-level high intensity ultra-endurance open-water swimming races. A well scheduled and well-prepared nutrition strategy is believed to have ensured optimal individual performance during Grand Prix events.
the 2 periods of the study: 1) control (3 weeks): intake of 500 ml/hour of water during each training session; 2) Intervention (3 weeks): intake of 500 ml/hour of a 6.5% CHO sport beverage during each training session. External load training was unchanged during all the study. Session-RPE (0-10 scale