OLDRIDGE, N. B., N. MCCARTNEY, A. HICKS, and N. L. JONES. Improvement in maximal isokinetic cycle ergometry with cardiac rehabilitation.Med. Sci. Sports Exerc, Vol. 21, No. 3, pp. 308–312,1989. It is unclear whether improvements in short-term (30 s) exercise capacity are associated with the increased aerobic exercise tolerance frequently observed in cardiac patients following training. Carefully selected patients with documented coronary artery disease were randomly allocated either to a control group (N= 10) or to 12 wk of endurance exercise training (N= 12); both progressive incremental cycle ergometer testing (maximal power output and peak &OV0312;O2) and 30 s maximal isokinetic cycle ergometry (peak power, total work, and fatigue index) were measured on entry into the study and 12 wk later. Initial maximum performance measures in progressive incremental exercise and in maximal short-term isokinetic cycling were similar in both groups. Following the training program, maximum power output measured during progressive incremental exercise increased by 21% (P< 0.005) and peak &OV0312;O2increased by 18% (P<0.005) in the exercise group, but they were unchanged in the control group. Isokinetic peak power and total work improved by 14% (P<0.001) and 11%, respectively, in the exercise group, whereas there were corresponding reductions of 6 and 8% in the control subjects, with little change in fatigue index in either group. The similar relative increases in isokinetic peak power and peak &OV0312;O2suggest that improvement in short-term exercise capacity may be an important contributor to the improvement in aerobic exercise tolerance frequently observed in cardiac patients undergoing an endurance exercise program.