Abstract
The minimum amount of physical activity needed to obtain health benefits has been widely determined. Unlikely, the impact of extreme amounts of very vigorous physical activity (VVPA, ≥ 8 metabolic equivalents) to the heart remains controversial. We aimed to evaluate the dose-response relationship between VVPA and heart rate variability (HRV) in adults. We selected 1040 asymptomatic individuals (60% women, 42 ± 15 years, 28 ± 6 kg/m2) from the Epidemiology and Human Movement Study (EPIMOV). Participants remained in the supine position for 10 min, and we selected an intermediate 5-min window for HRV analysis. The standard deviation of the RR intervals, root mean square of RR intervals, successive RR intervals that differ > 50 ms, powers of the low-and high-frequency bands and Poincaré plot standard deviations were quantified. Participants used a triaxial accelerometer (Actigraph GT3x+) above the dominant hip for 4–7 consecutive days for quantifying their physical activity. We also evaluated the maximum oxygen uptake () during an exercise test. We stratified participants into five groups according to the VVPA in min/week (group 1, ≤ 1.50; 2, 1.51–3.16; 3, 3.17–3.54; 4, 3.55–20.75; and 5, > 20.75). The linear trends of the HRV through the quintiles of VVPA were investigated. We used logarithmic transformations to compare the five groups adjusted for age, sex, cardiovascular risk, and . We found a better HRV with increased VVPA for all HRV indices studied (p trend < 0.05). However, group 5 did not differ from group 4 (p > 0.05) for none of the indices. We conclude that there is an incremental benefit of VVPA on HRV of asymptomatic adults. Since we found neither additional benefits nor the harmful impact of amounts of VVPA as high as 22 min/week on HRV, our results should not discourage asymptomatic adults to perform VVPA.
Highlights
Physical activity is defined as any body movement produced by skeletal muscles that result in energy expenditure higher than basal energy expenditure [1]
We have shown in the present study that excessive amounts of very vigorous physical activity, i.e., equal to or greater than 8 metabolic equivalents (MET), are associated neither with healthier nor with worse heart rate variability indices
Our results suggest a plateau concerning the benefit of very vigorous physical activity (VVPA) on Heart rate variability (HRV) and are very similar to the group considered as moderate-intensity in the study of Schnohr et al [20], i.e., between 6 and 12 MET, which showed a lower risk of mortality compared to non-runners, but no benefit over the light jogging group
Summary
Physical activity is defined as any body movement produced by skeletal muscles that result in energy expenditure higher than basal energy expenditure [1]. The relationship between excessive amounts and intensities of physical activity and cardiovascular health is not well elucidated. The results are controversial, Lavie et al [3] have observed in a systematic review of the literature that the achievement of an excessive amount of exercise, defined as > 60–90 minutes per session, is associated with a risk of cardiotoxicity and with deleterious effects on cardiovascular health. It has been observed that the combination of HRV indices may identify hypertensive patients at high risk to develop future vascular events [9]. It is associated with overtraining syndrome [10]
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