Re-evaluation of exercise prescription for Japanese type 2 diabetic patients by ventilatory threshold

Abstract

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<HR max<79%), heart rate reserve (50<HR reserve<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 2 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 ̇ O 2 ), work rate (WR), HR, ΔHR, %HR max, %HR reserve, and RPE were measured at VT. Type 2 DM patients had significantly lower V ̇ O 2 (3.6±0.4 metabolic equivalents (METs)) and WR (62±14 W) than controls ( V ̇ O 2 , 3.9±0.6 METs; WR, 74±13 W). %HR reserve, (32.6±7.7%) was also significantly lower compared with controls (37.6±8.3%), while %HR max, 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%HR max, 30%HR reserve, and RPE 12 is recommended in elderly diabetics and those with diabetic sensory neuropathy.