The Effects of Short-term Moderate Intensity Aerobic Exercise and Long-term Detraining on Electrocardiogram Indices and Cardiac Biomarkers in Postmenopausal Women

Objective: The purpose of this study was to investigate the effects of 12-week of moderate-intensity aerobic exercise and 5-month detraining on electrocardiogram (ECG) indices and serum levels of 25-hydroxivitamin D (Vit D), parathyroid hormone (PTH), calcium (Ca), and phosphorus (P) in postmenopausal women (PMWs).

Materials And Methods: Thirty-one PMWs (aged 50-70 yrs) were randomized to exercise (EX, n = 16) and control (C, n = 15) groups. EX group performed of 12-week of warm up- walking/jogging moderate intensity aerobic exercise training program- recovery (60 min/day, 3 days/week at 70% of maximal heart rate reserve), and then 5-month detraining remained. C group maintain their normal lifestyle during 8 months. The ECG indices and cardiac serum levels were measured at baseline, after 12-week exercise, and after 5-month detraining.

Results: After 12-week exercise intervention, P-R interval, serum PTH and serum Vit D were significantly increased in the EX group compared to the C group (P = 0.020, P = 0.001 and P = 0.001, respectively). After 5-month detraining, P-R segment and S-T interval were significantly decreased (P = 0.042 and P = 0.001, respectively) while serum Vit D was significantly increased (P = 0.014) in the EX group compared to the C group.

Conclusions: The results suggested that 12-week of moderate intensity aerobic exercise increased the P-R interval, PTH and Vit D, as severe Vit D deficiency status (below 10 ng/ml) improved to Vit D deficiency status (between 10 and 20 ng/ml) in PMWs. Also, long-term positive adaptations to aerobic exercise such as increased Vit D were observed even after 5-month detraining. In addition, P-R segment and S-T interval decreased after 5-month detraining in sedentary PMWs, which may be a sign of atrial positive adaptations to aerobic exercise.