Fig. 3.

SDH activity and integrated SDH activity per fiber type for adult, old and old-res muscle. SDH activity for adult, old and old-res muscle in control and overloaded condition for type A, X, and B fibers in the oxidative (a) and glycolytic (b) region of the muscle. c Mean SDH for adult, old and old-res mice in both control (black) and overloaded (white) conditions. SDH activity in old muscle was higher than in adult muscle (^a P < 0.05). SDH activity was higher in old compared to adult muscle for all three fiber types (P < 0.05). Furthermore, the SDH activity in IIB of the glycolytic region of the muscle was lower than of type IIB fibers in the oxidative region (^g P < 0.05). Resveratrol did only increase SDH activity in type IIB fibers of the glycolytic region of the muscle (P < 0.05). SDH activity was lower in type IIB compared to IIX fibers (^χ P < 0.01) and lower in IIX compared to IIA fibers (^α P < 0.01). Integrated SDH activity for adult, old, and old-res muscle in control and overloaded condition for type A, X, and B fibers in the oxidative region (d) and glycolytic region (e) of the muscle. f Mean integrated SDH for adult, old, and old-res mice in both control (black) and overloaded (white) conditions. Integrated SDH activity increased after overload for all three fiber types (P < 0.01). Old muscle showed a higher integrated SDH activity in type IIA fibers, compared to adult (P < 0.01). Type IIX fibers had a lower integrated SDH activity in the glycolytic region, compared to the oxidative region (P < 0.01). Data shown are mean ± SEM