Exercise was performed at the same absolute workload of 12 W and at a relative workload corresponding to 45%Wmax without (CON) or with (NAC) infusion of N-acetylcysteine in young sedentary (n= 8), older sedentary (n= 8) and older active (n= 8) subjects. Values are means ± SEM. †Significantly different from young sedentary within same condition, P < 0.05; *significantly different from control conditions, P < 0.05; #significantly different from rest, P < 0.05, ‡significantly different from older sedentary within same condition, P < 0.05.