Role of supplementary L-carnitine in exercise and exercise recovery.

L-Carnitine is a conditionally essential nutrient and plays an important role in mitochondrial β-oxidation. As a dietary supplement for athletes, L-carnitine has been investigated for its potential to enhance β-oxidation during exercise ultimately to improve performance. While some studies have shown a positive impact on VO(2 max) and other performance measures, other studies have found contradictory results. As such, investigations to a different mechanism by which L-carnitine supplementation could impact exercise and recovery were explored. Based on findings from cardiovascular research that L-carnitine enhances vascular endothelial function, an alternate hypothesis was developed. The hypothesis is centered on improving blood flow to muscle tissues and decreasing hypoxic stress and its resulting sequelae. Studies have shown a decrease in markers of purine catabolism and free radical generation and muscle soreness as a result of L-carnitine supplementation. Direct assessment of muscle tissue damage via magnetic resonance imaging also indicates the ability of L-carnitine to attenuate tissue damage related to hypoxic stress. L-Carnitine is regarded as a safe supplement for athletes and has been shown to positively impact the recovery process after exercise.