Effect of astaxanthin supplementation on cycling performance, muscle damage biomarkers and oxidative stress in young adults: a randomized controlled trial

Background The consumption of dietary supplements to enhance endurance performance and fitness is gaining popularity among professional athletes and nonathletes. Astaxanthin (AST), a natural ketocarotenoid, has been tested for its ergogenic, antioxidant, and tissue protective properties in young male adults. Methods Ten physically active male adults (22.5 +/- 0.9 years) were randomized into placebo or AST trials (according to CONSORT), and consumed placebo or AST (28 mg/d) supplements orally for 4 days. On day-4, participants performed an exhaustive cycling challenge at 75% maximum rate of O-2 uptake (VO(2)max), and the time to exhaustion (TTE) was recorded. Blood and gaseous samples were collected before, during, and immediately after cycling to determine changes in muscle damage, inflammation, oxidative stress, and substrate utilization. Results Short-term AST supplementation significantly enhanced exercise performance, as we found longer TTE in the AST trial (85.41 +/- 4.42 min) than in the placebo trial (72.11 +/- 2.24 min). Statistical analysis revealed a significant larger effect (P < 0.001; partial eta squared (eta(2)p) = 0.71) on enhanced TTE with AST. Exhaustive exercise-induced muscle damage, indicated by increased creatine kinase (CK) and lactate dehydrogenase release, was significantly (P < 0.05) decreased by AST. A significant time and treatment interaction effect for CK (P = 0.039, eta(2)p = 0.217) indicating potential attenuation of muscle damage by AST. In addition, lipid peroxidation, as evidenced by increased malondialdehyde levels during and immediately after exercise, was substantially inhibited by AST (P < 0.05). However, inflammatory markers (tumor necrosis factor-alpha and C-reactive protein) did not respond to either AST supplementation or exercise challenge. Substrate utilization during and after exercise appeared to be similar in both trials. Importantly, AST supplementation had no adverse effects on the 'profile of mood states' among participants. Conclusions Short-term AST supplementation could be a nutritional ergogenic aid to enhance endurance performance and attenuate exhaustive exercise-induced muscle damage or oxidative stress in young adults.