The Effect of Long-term Aerobic Exercises on Autonomic Imbalance in Postmenopausal Women

Objective: Study the effects of aerobic exercises on autonomic imbalance associated with menopausal women.

Methods: The study included twenty postmenopausal women (age 50.7± 0.86 mean ± SEM years old). All of them underwent 6 months of aerobic training program (3 sessions per week where every session is about one hour). Before and after the training program we measured the following parameters: 1) Heart rate variability indices using 24 hours ambulatory monitoring (Cardio Holter), both of time and frequency domain parameters were measured. 2) Serum levels of nitric oxide and catecholamines (adrenaline and noradrenaline). 3) Number of hot flashes per day.

Results: Six months of aerobic training program produced significant increase of all heart rate variability indices as compared with the starting levels: 1) Time domain parameters in the form of standard deviation of all normal RR intervals (SDNN), P<0.0001, and root mean square of successive RR intervals (rMSSD), P<0.001, where RR is the time between two successive R waves in the ECG. 2) Frequency domain parameters in the form of power in the low frequency range (LF), P<0.001 and power in the high frequency range (HF), P<0.0001. Chemical analysis revealed significant increase in serum level of nitric oxide, P < 0.0001 alongside with significant decrease in catecholamines levels (P<0.0001) for both adrenaline and noradrenaline) compared with the starting levels. Number of hot flashes per day was significantly decreased as compared to the starting number, P<0.001.

Conclusions: Regular moderate intensity aerobic exercises can induce significant improvement of the disturbed autonomic balance in postmenopausal women most probably through increasing NO production. The exercise would most likely have to be sustained in order to reduce long term risk.