“It should be noted that accumulating data suggest positive effects of BCAAs on moderate muscle damage—however, findings vary substantially across studies,” said the researchers from the School of Nutritional Sciences and Dietetics of the Tehran University of Medical Sciences. Their study was published in the journal Nutrition.
“We aimed to conduct a meta-analysis from randomized controlled trials (RCTs) to specify the effects of BCAA supplementation on [muscle soreness] and indirect markers of muscle damage in all studies with this subject,” they added.
Total studies and sample size
The researchers collected studies using Medline, Sport Discus, Scopus, and Google Scholar. Criteria for inclusion included: Randomized study design where BCAA supplementation is compared to a placebo group; at least one outcome measured muscle damage and soreness; BCAA applied before and immediately after exercise; and variables were measured within four days.
Eight randomized controlled trials that met all the criteria were chosen for analysis. Combined, the meta-analysis included 70 healthy study participants, all men, with a mean age of 23. The studies analysed were conducted between 2008 and 2015.
Exercises included heavy resistance training, soccer, marathon, and several other sports study drills such as a drop-jump test or neuromuscular electrostimulation exercise.
BCAA supplementation has positive effects to post-exercise muscle damage
The studies pooled together revealed that BCAA applied during exercise “is not effective on muscle soreness at follow-up time,” the researchers wrote. The studies analysed measured muscle soreness at 24, 48, 72, and 96 hours after exercise.
However, the studies did reveal that BCAA had a statistically significant effect on reducing the efflux of creatine kinase—a marker for muscle injury—after exercise compared to placebo supplemented groups. This means that BCAA may have a positive effect after exercise-induced muscle damage.
Additionally, there was significantly lower values of creatine kinase concentration for the BCAA supplement groups compared to study participants who only rested.
Beyond this, there were still some inconclusive areas because of high heterogeneity of the results from studies analysed. “The variations in BCAA classifications between countries; different manufacturers of BCAA; and the percent of leucine, isoleucine and valine may contribute to the inconsistencies in results,” according to the researchers.
Published online ahead of print: https://doi.org/10.1016/j.nut.2017.05.005
Branched-chain amino acid supplementation and exercise-induced muscle damage in exercise recovery: A meta-analysis of randomized clinical trials
Authors: Mohammad Hossein Rahimi, et al