Abstract
BackgroundDecreased heart rate variability (HRV) is associated with a higher risk of mortality. Overall, postmenopausal women have lower levels of HRV than premenopausal women, which may be additionally complicated by lifestyle related behaviors such as physical inactivity and obesity. Though cardiorespiratory exercise training increases HRV, little is known regarding the exercise dose necessary to promote this improvement.Methodology/Principal FindingsOur primary aim was to measure HRV in post-menopausal women following 6-months of exercise training. We examined supine resting HRV in 373 post-menopausal women (45–75 y) after 6-months of randomly assigned and double-blinded administered exercise training exercise training at 50%, 100% and 150% of the NIH Consensus Development Panel's recommended minimal physical activity level. This corresponded to 4, 8, or 12 kcal/kg per week (KKW) of energy expenditure. At baseline, we observed no significant differences in HRV or hormone replacement use between treatment groups. However, we did observe that Caucasian women and those taking antidepressant medications had lower levels of baseline HRV. After 6-months of exercise intervention, we observed a dose dependent increase in all parasympathetically derived time and frequency domain measurements across exercise groups after adjustment for age, ethnicity, antidepressants, and baseline rMSSD (all, P<0.001). For example, the parasympathetic index rMSSD was greater than control (23.19±1.0) for the 4-KKW (25.98±0.8; P = 0.14), 8-KKW (27.66±1.0; P<0.05), and 12-KKW (27.40±0.0; P<0.05) groups at follow-up.Conclusions/SignificanceModerate intensity exercise training exercise is sufficient to improve HRV in previously sedentary postmenopausal women in a dose-dependent manner, as 4-KKW is insufficient to improve parasympathetic indices of HRV, while 12-KKW conferred no greater improvement than 8-KKW.Trial RegistrationClinicaltrials.gov NCT 00011193
Highlights
Menopause represents a key transition period in a woman’s health
The assessment of heart rate variability (HRV) in postmenopause is important because cardiovascular (CV) disease typically occurs later in women than in men; yet, the fact remains that CV disease is one of the two leading causes of death in women [6,7]
We examined the HRV response of women participating in the Dose-Response to Exercise in Women study (DREW) who participated in 6-months of strictly monitored, moderate intensity exercise training at approximately 50%, 100%, and 150% of the minimal National Institutes of Health (NIH) Panel’s recommendation for physical activity
Summary
A fundamental etiology associated with menopause is the intricate link between estrogen metabolism and the autonomic nervous system. Autonomic nervous system balance can be assessed non-invasively via the use of heart rate variability (HRV). While a thorough review of HRV can be obtained elsewhere,[1] HRV is clinically useful because reduced HRV is associated with an increased risk of CV disease, type II diabetes and insulin resistance and has been shown to be reduced in postmenopausal women as compared with premenopausal women [2,3,4,5]. A lifestyle behavior that has a significant affect on the metabolic processes surrounding CV disease is cardiorespiratory exercise training. Decreased heart rate variability (HRV) is associated with a higher risk of mortality. Though cardiorespiratory exercise training increases HRV, little is known regarding the exercise dose necessary to promote this improvement
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
