Associations between baseline autonomic function and recovery from hamstring delayed-onset muscle soreness

The purpose of this study was to assess the relationship between baseline heart rate variability (HRV) and bioelectrical phase angle and hamstring recovery at 72 and 96 h after a DOMS-inducing protocol in physically active men. Following experimentally induced hamstring DOMS in 46 physically active male participants aged 20.78 ± 2.19 years, recovery outcomes including maximal isometric strength, active knee extension range of motion (AROM), pressure pain threshold, and perceived soreness were evaluated at baseline and at 48, 72, and 96 h. Associations between baseline physiological markers and changes in recovery outcomes were subsequently examined using correlation analyses. Statistical significance was set at p < 0.05. Changes in perceived soreness at 72 h showed moderate positive correlations with baseline HRV ( r = 0.45), DFA-alpha 1 ( r = 0.41), and stress index ( r = 0.35), and moderate negative correlations with SDNN ( r = -0.33) and RMSSD ( r = -0.37). At 96 h, correlations with HRV ( r = 0.33), DFA-alpha 1 ( r = 0.38), SDNN ( r = -0.29), and RMSSD ( r = -0.34) remained significant (all p < 0.05). In addition, at 72 h post DOMS left limb ROM demonstrated a moderate positive correlation with DFA-alpha 1 ( r = 0.32), while changes in right limb ROM were moderately positively correlated with phase angle ( r = 0.31). Additionally, changes in left limb peak torque exhibited a moderate negative correlation with HRV ( r = -0.32). Baseline HRV-derived indices, particularly SDNN and RMSSD, were associated with perceived soreness in the later stages of recovery from hamstring DOMS. On the other hand, relationships with objective recovery outcomes were less consistent. Phase angle showed limited and outcome-specific associations, suggesting it may be less sensitive for monitoring acute recovery after eccentric exercise. These results suggest that autonomic status may be involved in interindividual variability in the perceptual response to muscle damage.