Plain language summary
Exercise-induced fatigue can limit sports performance and training goals. Branched chain amino acids (BCAA) have been shown to prevent fatigue and improve recovery but can also lead to excess ammonia which in turn may contribute to fatigue. Citrulline has been shown to counteract this ammonia accumulation and may increase nutrient delivery to the muscles through promoting nitric oxide synthesis. Alpha-glycerylphosphoryl choline (A-GPC), which releases choline, is thought to increase peak power and delay fatigue in athletes. This randomised, double-blind, placebo-controlled crossover trial of 30 trained male cyclists evaluated supplementation of the combination of BCAA, citrulline and A-GPC for 7 days on the performance in a 20 km cycling time trial and a high intensity endurance cycling (HIEC) test. Outcome measures for both tests were time to completion, peak and average power output and subjective measures of exertion. In the time trial, cyclists had significantly higher peak performance when taking the supplement compared to placebo, whilst they experienced less muscle soreness and greater mental/focus concentration on the placebo. There were no differences between supplement and placebo for time to completion, average power, overall energy, muscle fatigue or levels of exertion. In the HIEC test, there was a significantly longer time to fatigue with the supplement, whilst there was again less muscle soreness with the placebo. There were no differences for muscle fatigue, overall energy or mental focus/concentration. The authors conclude that this combination of nutrients may help improve performance in sports requiring muscle strength and endurance.
Abstract
BACKGROUND Nutrition plays a key role in training and athletic performance and dietary supplements can make a small, but potentially valuable, contribution to achieving peak athletic performance. This study is the first to investigate the effects of supplementation from the combination of BCAAs, L-citrulline, and A-GPC on exercise performance. METHODS In this randomized, double-blind, crossover study 30 male trained cyclists (age: 43.7 ± 8.5 years) completed a 20 km cycling time trial (TT) test and a high intensity endurance cycling (HIEC) test following a 7-day supplementation period with either a supplement containing 8 g BCAAs, 6 g L-citrulline, and 300 mg A-GPC or a placebo (15 g maltodextrin). For each trial, mean values for time to completion, peak and average power output, OMNI rating of perceived exertion, and visual analogue scale (VAS) responses on perceived exertion were computed for the 20 km TT test. Mean values for time to fatigue and VAS responses on perceived exertion were computed for the HIEC test. Procedures for dietary intake and exercise patterns were implemented to achieve consistency throughout the study period. RESULTS There was a significant increase (p = .003) in peak power in the 20 km TT (354.27 ± 87.88 and 321.67 ± 63.65, for supplement and placebo trials, respectively) and a significant increase (p = .001) in time to fatigue in the HIEC test (0:19:49 ± 0:11:13 min and 0:14:33 ± 0:09:59 min, for supplement and placebo trials, respectively) with the test supplement compared to the placebo. With the test supplement, there was an average increase in TT peak power of 11% and an average increase in time to fatigue of 36.2% in the HIEC test compared to the placebo. There was no significant improvement in time to completion, average power, OMNI rating of perceived exertion, or VAS responses on perceived exertion in the TT test and no significant improvement in VAS measures of perceived exertion in the HIEC test. CONCLUSIONS The combination of BCAAs, L-citrulline, and A-GPC used in this study improves cycling performance and may be useful for individuals seeking to improve athletic performance, particularly in disciplines requiring lower body muscular strength and endurance.
Methodological quality
Jadad score
:
2
Allocation concealment
:
Not applicable
