Short‐term effects of weight‐loading on heart rate variability in obese adults

Abstract Weight‐loading reduces body fat, but its effects on cardiac autonomic modulation remain unclear. We examined heart rate variability (HRV) during free‐living weight‐loading in adults with class I obesity. Fifty‐one participants (27 females) were randomized to wear a heavy (11% of body weight) or a light vest (1%) for 8 h/day for 15 days. Twenty‐four‐hour ECG recordings were obtained before and on day 15. Heart rate (HR), relative HR reserve (%HRR), and time‐ and frequency‐domain HRV indices were analyzed across four predefined periods: morning (rest), afternoon (vest‐usage), evening, and night. During the afternoon period, the high versus low load increased HR ( p = 0.0496) and %HRR ( p = 0.03), while reducing SDNN (standard deviation of normal‐to‐normal intervals; p = 0.01) and RMSSD (root mean square of successive differences; p = 0.002). In females, but not in males, high load was associated with lower high‐frequency power (P HF ), higher low‐frequency power (P LF ), and an increased P LF /P HF ratio during the afternoon, consistent with reduced parasympathetic modulation. No differences between groups were observed during resting periods. These findings indicate that weight‐loading increases cardiovascular workload and transiently alters autonomic modulation during active vest use, with more consistent responses in females and no sustained resting adaptations.