Comparison of Linear and Nonlinear HRV Dynamics Across Exercise Intensities After Menopause.

The authors compared the linear and nonlinear heart rate variability dynamics from rest through maximal exercise in postmenopausal women who trained at either moderate or high intensities. The outcome variables included the RR triangular index, TINN, SD1, SD2, SD1/SD2, DFA α1, DFA α2, and α1/α2. Maximal exercise reduced SD1, SD2, DFA α1, DFA α2, α1/α2, RRTri, and TINN in both groups and increased SD1/SD2 (p < .05). Two minutes of active recovery produced significant increases in SD1, SD2, DFA α1, and TINN, compared with exercise in both groups (p < .0001). There was also a significant main effect between groups for RRTri during exercise recovery, with the moderate group achieving higher levels (p < .04). The authors have shown that both moderate and vigorous exercise training can lead to a healthy response to maximal exercise and recovery, with the moderate group having a slightly improved recovery in the triangular index.

Is Vigorous Exercise Training Superior to Moderate for CVD Risk after Menopause?

Postmenopausal women have an increased risk for cardiovascular disease through many factors, such as a sedentary lifestyle and reduced heart rate variability (HRV). Endurance training improves coronary risk but the role of exercise intensity is unclear. The purpose of this observational study was to evaluate the effects of moderate versus vigorous exercise on cardiovascular disease risk in postmenopausal women. Thirty-six postmenopausal women who self-reported training at moderate (3-5.9 METS; n=18; age 58.9±4.4yr) or vigorous intensities (>6 METS; n=18; age 59.7±5.2yr) participated. C-reactive protein (CRP), HRV, VO 2 max, and stress (Perceived Stress Survey, Menopause Rating Scale) were measured. Groups were compared using independent samples t- tests, and associations of exercise intensities with CRP and HRV were assessed using multiple regression. CRP, HRV, and VO 2 max were similar ( p >0.05). Vigorous exercise had lower stress subscale scores ( p <0.01) and higher counter-stress subscale scores compared to moderate ( p <0.05). There was a positive association between time spent in vigorous exercise and HRV ( p <0.05).Vigorous exercise may not confer additional benefits in CRP and HRV over moderate, except for stress reduction. However, more time spent in vigorous exercise was associated with higher HRV. Therefore, increased parasympathetic tone may provide cardioprotection after menopause.