Effects of Mitochondria-Targeted Antioxidant Supplementation on Mitochondrial Adaptations to Endurance Training in Healthy Men

Abstract

The production of reactive oxygen species (ROS) during exercise is one signal for training-induced mitochondrial biogenesis. Previous studies have shown that antioxidant supplementation blunts mitochondrial adaptations to exercise training via suppression of ROS production. PURPOSE: To determine the effects of mitochondria-targeted antioxidant (mtAO) supplementation on mitochondrial adaptations to chronic exercise training. METHODS: Young (22 ± 3 yr), healthy men (n = 19) were randomized to receive either mtAO (n = 9) or placebo (n = 10). Participants performed cycle training for 3-weeks at 50-70% of maximal oxygen uptake (VO2max). VO2max and an in vivo assessment of mitochondrial oxidative capacity were assessed before and after training. Mitochondrial oxidative capacity was assessed via post-exercise recovery kinetics of muscle oxygen consumption using near infrared spectroscopy (NIRS) in the vastus lateralis (VL) muscle. RESULTS: Exercise training increased VO2max (baseline: 40.1 ± 4.8 ml/kg/min; after training: 42.8 ± 3.9 ml/kg/min, main effect: p < 0.001), but no differences were detected between treatment groups (training × treatment: p = 0.29). Similarly, exercise training increased mitochondrial oxidative capacity rate constants (baseline: 1.8 ± 0.3 min-1; after training: 2.2 ± 0.5 min-1, main effect: p < 0.002), with no differences between treatment groups (training × treatment: p = 0.39). CONCLUSIONS: Mitochondria-targeted antioxidant supplementation does not alter mitochondrial adaptations to endurance exercise training. Further, our data indicate that three weeks of cycle training enhances mitochondrial oxidative capacity in the VL as measured by NIRS.