Asociación entre actividad física medida objetivamente y variabilidad de la frecuencia cardíaca en adultos sanos de atención primaria de salud

Objective: To assess the association between daily physical activity and heart rate variability in adults without established cardiovascular disease enrolled in a primary health care unit.Methods: This cross-sectional study included 197 apparently healthy individuals (mean age 47 ± 13 years; 58% female) enrolled in a primary health care unit. Heart rate variability indices (time domain, frequency domain, and nonlinear indices) were derived from 5-minute resting RR-interval recordings while participants breathed at 12 breaths per minute. Daily physical activity was recorded over 7 consecutive days using accelerometers, with data classified into sedentary time, light, and moderate-to-vigorous physical activity. Correlation and multivariate linear regression analyses examined associations between daily physical activity and heart rate variability indices.Results: Sedentary time and light physical activity were not associated with any heart rate variability index. Adjusting for age, sex, and resting heart rate, moderate-to-vigorous physical activity was inversely correlated with the low-to high-frequency power ratio (r²= -0.18). Moderate-to-vigorous physical activity (β= -0.14), along with sex (β= 0.32), waist circumference (β= 0.14), and age (β= 0.05), was an independent predictor of the low-to-high frequency power ratio, explaining 2.3% of its variance.Conclusion: Although a cardioprotective effect of moderate-to-vigorous physical activity on heart rate variability was not definitively demonstrated, an inverse association was found with the low-to-high frequency power ratio. Sedentary time and light activity, however, were not associated with cardiac autonomic function.