Research has demonstrated the relationship between astaxanthin supplementation and improved muscle endurance and recovery. In support of this research several studies have suggested possible causal relationships. Two studies, one human and the other animal showed significantly lower serum lactate levels after exercise with use of astaxanthin. In another animal study astaxanthin was found to attenuate exercise-induced damage in skeletal and heart muscle, including inhibition of neutrophil infiltration into the tissues. This study also showed inhibition of reatine kinase activity by the astaxanthin group. Also, in a human rheuology study, astaxanthin supplementation showed significant increase in peripheral blood flow.