Effects of carnosine supplementation on physical endurance: a placebo-controlled randomized clinical trial

Background Carnosine (β-alanine-L-histidine) is an endogenous dipeptide found in abundance in highly metabolic tissues such as skeletal muscle and the brain, where it is thought to play a role in intracellular buffering, and thereby, promote anaerobic glycolysis. Due to its perceived ability to support muscle energetics, carnosine, and its precursor, β-alanine, have found widespread use as performance-enhancing supplements. Nevertheless, the utility and efficacy of carnosine in enhancing physical performance have not been rigorously evaluated.Methods We conducted a placebo-controlled clinical trial in which 299 participants were randomized to consume either placebo or carnosine-containing capsules (2 g per day). Several assessments of physical performance (hand grip strength, bilateral calf raise, 2-min step test, gait speed) were measured before initiating supplementation (Baseline: Visit-2) and after approximately 6 week (Visit-3) and 12 week (Visit-4) of supplementation. At each clinical visit, blood and urine were also collected. For Visit-3 and Visit-4, absolute changes and percent changes from baseline were calculated for each physical function measurement.Results At Visit-3 we observed a statistically significant (p = 0.018) increase in the calf raise measure (number of bi-lateral flexions to exhaustion) for those in the carnosine supplementation group younger than 40 years of age. At Visit-4 we observed a statistically significant (p = 0.010) increase in the number of steps for males in the carnosine supplementation group greater than 40 years age and a trend toward significance (p = 0.06) for all males taking carnosine. No significant (p < 0.05) differences were observed in the carnosine versus placebo supplementation groups for any other physical performance measure.Conclusions In select age groups, carnosine supplementation improves muscular and cardiorespiratory endurance but not grip strength. The benefits appeared to be limited to males. Carnosine supplementation is likely to have beneficial effects in those undertaking short-term repetitive movements.