Branched Chain Amino Acids
A RCT by Wiśnik et al was designed to examine the effect of BCAA ingestion on psychomotor performance by analyzing changes in the multiple-choice reaction time (MRT) during treadmill running simulation locomotor activity.(Wiśnik et al. 2011) Professional male soccer players (n=10) with a mean age of 25 years performed a treadmill exercise that simulated a soccer game twice within a 1-week interval. One hour before exercise, participants were given either 7g BCAA (40% leucine, 40% valine, and 20% isoleucine) mixed with 250mL nonsweetened, vanilla-flavored liquid pudding containing 3.4g carbohydrates, 1.0g protein, and 1.15g fat. A pudding without BCAA was used as ...view middle of the document...
The results revealed that BCAA supplementation significantly shortened MRT (p<0.01) 1-hour after ingestion during two 45-minute exercise bouts. Based on these results, the authors concluded that BCAAs have a beneficial influence on psychomotor performance during exercise and indirectly supports the hypothesis of serotonin contribution to the central fatigue. Furthermore, Wiśnik et al. concluded that BCAA supplementation might be recommended in sport activities with intensity changing from low to very high and requiring quick responses to external signals, such as soccer and other team games.
This study had many limitations some of which were the small sample size, the non-validated tool to assess for MRT, and the conclusions that the authors drew from their findings. The results may have shown a statistical significance between reduced MRT time and BCAA supplementation but these findings only show a correlation to improved psychomotor performance, not causation. This study could support further research into the association of BCAAs and athletic performance but it does not have the evidence to be considered clinically significant.
A RCT by Knechtle et al. investigated the effect of branched-chain amino acid supplementation on skeletal muscle damage and renal function during a 100-km ultra-marathon.(Knechtle et al. 2012) Ultra-marathoners (n=28) were randomly assigned to two groups: BCAA supplementation or a control group. One-hour prior to the start of the ultra-marathon, each participant received a package of tablets containing either the BCAA or the placebo. The BCAA tablet consisted of 50g of amino acids; 20g of which were BCAA, accounting for 40% of the supplement. Participants in the BCAA group consumed 12 tablets prior to the race then another 4 tablets at each of the 17 aid stations along the race course. The placebo tablets were intended to be consumed at the same time as the BCAA group but due to the manufactures concern regarding high calcium amounts in the tablets, the placebo control was abandoned. Parametric and non-parametric testing within and between groups was performed.
Once linear regression controlled for personal best times between the groups, the study found no statistical significance between the BCAA group and the control group (p> 0.05). The authors concluded that their hypothesis was wrong because they found no difference between the BCAA group and the control group. A strength of this study was the statistical analysis that was used to control for the confounding variable of the different speeds of the participants. Limitations of this study were the failed placebo which impacted the blinding of the study, and the BCAA supplement that had a higher percentage of non-branched-chain amino acid which could have impacted results.
A study by Coomes and McNaughton examined the effects of BCAA supplementation on serum indicators of muscle damage after prolonged exercise.(Coombes and McNaughton 2000) ...