Figure 3. High-intensity interval training increases activity and content of the mitochondrial enzyme citrate synthase.

A, maximal activity (mmol (kg protein)⁻¹ h⁻¹ w.w.) of citrate synthase (CS) measured in whole muscle homogenates prepared from muscle biopsy samples (v. lateralis) obtained before (pre) and after (post) training. B, protein content of CS before (pre) and after (post) training. *P < 0.05 vs. pre-training. Values are means ±s.e.m. Representative Western blots from two subjects are shown.