Figure 1.Chronic contractile activity-evoked increases in skeletal muscle endurance performance and mitochondrial content are reduced in old, compared to young animals. (A).Fatigue resistance during 5 min
of 1 Hz in situ stimulation of the control (CON, open squares) and
chronically stimulated (STIM, closed circles) tibialis anterior muscles
from young (solid lines) and old (dashed lines) animals (n = 7-8). (B)
Electron micrographs depicting skeletal muscle morphology and SS and
IMF mitochondrial volumes in young and old, control (CON, open bars) and
chronically stimulated (STIM, closed bars) extensor digitorum longus (EDL)
muscle sections. All images were taken at the same magnification. Scale bar
located at the lower right of each picture represents 1 μm. (C) COX
enzyme activity in EDL muscle homogenates (n = 9-13). Data represent
the mean ± SEM. * P < 0.05 vs. Young; ¶ P < 0.05 vs.
CON.
