Elevated heart rate variability in physically active postmenopausal women: a cardioprotective effect?

Area of Science:

• Cardiovascular Physiology
• Exercise Science
• Women's Health

Background:

• Coronary heart disease (CHD) and cardiac sudden death (CSD) incidence increase post-menopause.
• Low heart rate variability (HRV) is a known risk factor for CHD and CSD.
• Physical activity is associated with lower CHD and CSD incidence in women.

Purpose of the Study:

• To test if HRV is greater in physically active postmenopausal women compared to less active controls.
• To hypothesize that greater HRV in active women is linked to elevated spontaneous cardiac baroreflex sensitivity (SBRS).

Main Methods:

• Measured HRV (time and frequency domains) and SBRS using the sequence method.
• Data collected during controlled breathing in supine, sitting, and standing postures.
• Included 9 physically active and 11 age-matched less active postmenopausal women.

Main Results:

• Physically active women had lower body weight, BMI, and body fat percentage, with higher maximal oxygen uptake.
• Active women exhibited significantly higher HRV across all postures and breathing conditions.
• SBRS was also significantly higher in active women, explaining ~70% of the variance in high-frequency HRV.

Conclusions:

• Physically active postmenopausal women demonstrate superior HRV compared to their less active counterparts.
• SBRS is a major determinant of HRV in active postmenopausal women, suggesting a role in cardiac autonomic regulation.
• Findings suggest a potential cardioprotective mechanism associated with physical activity in postmenopausal women.