A, basal (V0, pyruvate + malate), and maximal (Vmax, 1 mm ADP) respiration rates measured on saponin-permeabilized fibres and reported relative to citrate synthase (CS) activity. B, acceptor control ratio (ACR, Vmax/V0). Values are means ± s.e.m. (n = 8). Different superscripts denote significantly different values.