Atividade física, tempo sedentário e modulação autonômica cardíaca pós-exercício em crianças com obesidade: um estudo transversal

Abstract

Introduction: Childhood obesity has been associated with autonomic dysfunction, with reduced parasympathetic modulation of heart rate. Physical activity (PA) is an important protective factor, however evidence on its relationship with post-exercise autonomic recovery in children with obesity remains limited. Objective: To investigate the associations between PA levels, sedentary time and post-exercise heart rate variability (HRV) in children with obesity. Methods: This was a cross-sectional observational study. Eighty-four children with obesity, aged 6 to 12 years, were evaluated for PA levels using accelerometry and autonomic function through the natural logarithm of RMSSD every 30 seconds post-exercise (LnRMSSD30) during the 5-minute recovery period. LnRMSSD30 is a normalized measure of HRV that reflects the parasympathetic nervous system activity on the heart. Global vagal recovery was also assessed using the area under the curve (AUC). Associations between PA (moderate and vigorous), sedentary time (ST) and post-exercise HRV were analyzed. Results: Vigorous physical activity (VPA) showed a positive association with autonomic recovery (b = 0,31; IC95% = 0,08 – 0,54; p = 0,009), while ST was negatively associated (b = -0,25; IC95% = -0,48 – -0,02; p = 0,033). Moderate physical activity (MPA) did not show significant association with LnRMSSD30 between groups. AUC was significantly associated with MPA (b = 0,06; IC95% = 0,01 – 0,12; p = 0,027), VPA (b = 0,26; IC95% = 0,04 – 0,48; p = 0,023) and ST (b = -0,01; IC95% = -0,03 – -0,00; p = 0,027). Conclusion: Children with obesity who engaged in higher levels of VPA and lower ST demonstrated better post-exercise autonomic modulation. These findings highlight the importance of promoting active lifestyles for children's health.