EFFECT OF ECCENTRIC VERSUS CONCENTRIC EXERCISE TRAINING ON MITOCHONDRIAL FUNCTION

Introduction: The effect of eccentric (ECC) versus concentric (CON) training on metabolic properties in skeletal muscle is understood poorly. We determined the responses in oxidative capacity and mitochondrial H2O2 production after eccentric (ECC) versus concentric (CON) training performed at similar mechanical power. Methods: Forty-eight rats performed 5- or 20-day eccentric (ECC) or concentric (CON) training programs. Mitochondrial respiration, H2O2 production, citrate synthase activity (CS), and skeletal muscle damage were assessed in gastrocnemius (GAS), soleus (SOL) and vastus intermedius (VI) muscles. Results: Maximal mitochondrial respiration improved only after 20 days of concentric (CON) training in GAS and SOL. H2O2 production increased specifically after 20 days of eccentric ECC training in VI. Skeletal muscle damage occurred transiently in VI after 5 days of ECC training. Conclusions: Twenty days of ECC versus CON training performed at similar mechanical power output do not increase skeletal muscle oxidative capacities, but it elevates mitochondrial H2O2 production in VI, presumably linked to transient muscle damage. Muscle Nerve50: 803-811, 2014