“The purpose of this study was to examine if branched chain amino acid and carbohydrate versus carbohydrate-only sports drink supplementation attenuated markers of muscle damage while preserving performance markers following 3 days of intense weight training,” Wrote researchers from Auburn University in the Journal of the International Society of Sports Nutrition.
Though previous studies support the role of BCAAs in enhancing post-exercise muscle protein synthesis and reducing muscle proteolysis, the current study found that BCAA plus carbohydrate supplementation did not reduce the decline of lower body strength or improve select markers of muscle damage/soreness, compared to carbohydrate supplementation over three consecutive days of intense lower-body training.
Participants and study design
Thirty resistance-trained males participated in the study, which went over five days. All participants were also given standardized pre-exercise meals of cereal bars throughout the course of the study.
The first week was used for baseline measurements. The following week, participants performed 10 sets of five repetitions at 80% of their repetition maximum barbell back squat for three consecutive days. Participants were randomly assigned to consume either BCAA and carbohydrates or just carbohydrates immediately after the exercises.
Immediately after exercises, participants were randomly assigned to consume one of two commercial products in 600 mL of tap water: 1) Branched chain amino acid with carbohydrates (AMINO1 by MusclePharm Corp., who provided the supplement as well as some funding) which contains 10 kcal, 3 g L-leucine, 1 g L-isoleucine, and 2 g L-valine with 2 g of non-sugar carbohydrates per two servings, or 2) 42 g of carbohydrates (Powerade) per serving with 168 kcal, 40 g sugar (57% fructose, 39% glucose, 4% sucrose, and the remainder are trace amounts of lactose and maltose).
“While these supplements were not standardized to carbohydrate or calorie content, our intent was to provide a practical comparison between these two products,” the researchers wrote.
“Alternatively stated, we surmised that (in a real-world setting) participants would either consume a sports drink-like carbohydrate beverage or the experimental BCAA-carbohydrate beverage and, thus, we compared two servings of each supplement regardless of calorie or carbohydrate content,” they added.
Observations: Muscle soreness and post-exercise strength
After the trials and analyses, the researchers wrote that they found BCAA plus carbohydrate supplementation “was not able to reduce decrements in performance variables, markers of muscle damage and perceived muscle soreness increased over the study duration in both groups.”
They found that after three lifting bouts, the BCAA and carbohydrate supplemented group did not experience any significant performance outcomes compared to the carbohydrate group, as the participants’ lower body strength decreased in the same way between groups after the lifting bouts.
This outcome contrasted a previous study, which found that “250 mg/kg of leucine following 100 depth jumps and 6 sets of 10 repetitions on eccentric leg presses, and subsequently observed a greater maintenance of isometric squat force relative to placebo and control groups.”
“The reason for our findings are likely related to the resistance training protocol being too much of a muscle-damaging stimulus,” they wrote.
In addition, the researchers also found that BCAA plus carbohydrate supplementation, compared to just carbohydrate, did not differentially alter muscle soreness and reduced exercise-induced increases in monocyte differentials.
“It would have been nice to have a non-supplemented control or placebo”
The researchers said that limitations of their study included not standardizing carbohydrate or calorie content, and that the training protocol was very brief “and does lack a certain degree of external validity.”
Jose Antonio, PhD, editor-in-chief of the Journal of the International Society of Sports Nutrition, told NutraIngredients-USA that “it would have been nice to have a non-supplemented control or placebo.”
Although the study concluded that adding BCAA to a carbohydrate post-workout supplement does not help reduce the decline of muscle strength or remedy perceived muscle soreness, Antonio thinks the combination is still necessary.
“Protein + carbohydrate is still your best bet in terms of post workout recovery,” he said. “Basically this study shows no difference between BCAAs and carbohydrate. However, by themselves, neither is a good standalone recovery strategy.”
“Carbohydrate is important for glycogen restoration. But ultimately, you'll need protein to promote the repair of skeletal muscle,” he added.
Source: Journal of the International Society of Sports Nutrition
Published online, DOI: 10.1186/s12970-016-0142-y
Authors: Wesley C. Kephart, et al.