WEIGHT LOSS IMPROVES HEART RATE RECOVERY RESPONSE IN OBESE SUBJECTS

Abstract

The magnitude of the decrease in heart rate during the minutes after completion of exercise, defined as heart rate recovery (HRR), has been shown to be an independent predictor of cardiac mortality. Obesity is associated with the impaired autonomic control of heart rate, however, no evaluation of HRR in obese subjects has been demonstrated previously. PURPOSE To determine the effect of weight loss program on HRR in obese subjects. METHODS Changes of heart rate response and oxygen uptake during sub-maximal treadmill exercise test, were measured in 18 obese subjects (13 males, age 39 ± 8 y, BMI 35.9 ± 6.5 kg/m2) before and after a 12-week weight loss program. The program included supervised exercise session and dietary consultation once a week. HRR was defined as the change from peak heart rate to that measured 2 minutes later during the treadmill test. RESULTS The weight loss program resulted in a 10% weight reduction (p < 0.01) associated with a significant increase in maximal oxygen uptake (24.9 ± 5.5 to 28.7 ± 6.6 ml/kg/min, p < 0.01). Although resting heart rate (75 ± 17 to 70 ± 10 bpm, NS) and peak heart rate (153 ± 25 to 156 ± 19 bpm, NS) remained unchanged, HRR at 2 minutes improved from 51 ± 12 to 56 ± 14 bpm (p < 0.05) after the weight loss program. CONCLUSION HRR increases with weight loss in obese subjects. This increase appears to reflect improved autonomic control of the heart, leading to the better clinical outcome.