Prescription of aerobic exercise for Type 2 diabetes mellitus (Type 2 DM) in clinical practice is frequently based on exercise intensity at maximum heart rate (60 < HRmax < 79%), heart rate reserve (50 < HRreserve < 74%), and rating of perceived exertion (12 < RPE < 13). We examined these parameters in Japanese males with Type 2 DM at ventilatory threshold (VT) to investigate the exercise capacity of Type 2 DM patients and re-evaluate the exercise prescription. Fifty-six Japanese Type ? DM males without autonomic neuropathy [age, 53.5 +/- 7.7 years; body mass index (BMI), 23.7 +/- 3.6 kg/m(2)] were enrolled and compared with 56 age- and BMI-matched healthy Japanese males. VT was determined breath by breath during exercise test using a ramp protocol and rates of oxygen consumption ((V) over dotO(2)), work rate (WR), HR, Delta HR, %HRmax '%HRreserve, and RPE were measured at VT. Type 2 DM patients had significantly lower (V) over dot O-2 (3.6 +/- 0.4 metabolic equivalents (METs)) and WR (62 +/- 14 W) than controls ((V) over dot O-2 3.9 +/- 0.6 METs; WR, 74 +/- 13 W). %HRreserve, (32.6 +/- 7.7%) was also significantly lower compared with controls (37.6+/-8.3%), while %HRmax, was not different. RPE was also similar in diabetics (12.4 +/- 1.5) and controls (12.9 +/- 1.2). however, it was significantly lower in diabetic patients aged 60-69 years (11.8 +/- 2.0) and those with distal symmetric sensory neuropathy (12.2 +/- 1.0). Our results indicate reduced exercise capacity in Japanese Type 2 DM males and the exercise intensity of 60%HRmax, 30%HRreserve, and RPE 12 is recommended in elderly diabetics and those with diabetic sensory neuropathy. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.