Muscle biopsy, respiratory chain, and citrate synthase enzymes activities Skeletal muscle sample from vastus lateralis muscle was performed in every participant using a standard Bergström technique[7, 8]. Biopsy was performed at fasting conditions. About 200 mg of wet weight was obtained. The sample was immediately microdissected, weighed, divided for respective analyses and snap-frozen in liquid nitrogen and stored in -80oC until analyses.