Author(s): LOPES STORNIOLO, J., ZARRILLI, A., CAVALLARI, P., Institution: AUXOLOGIC ITALIAN INSTITUTE, IRCCS , Country: ITALY, Abstract-ID: 2053

INTRODUCTION:
Early recovery after intense running involves simultaneous autonomic, metabolic, and neuromuscular processes that may not develop at the same rate. We examined whether 10-minute active versus passive recovery influences the balance (“decoupling”) between autonomic recovery (RMSSD) and neuromuscular recovery (reactive strength index-modified, RSImod), and whether metabolic recovery (lactate clearance) helps explain this pattern.
METHODS:
Fourteen endurance-trained runners completed two maximal incremental treadmill tests in a randomized crossover design. After each test, participants either performed 10 minutes of low-intensity running (Active) or stood still (Passive) to recover. RSImod and HRV were measured before the maximal test and after the recovery period, with RSImod calculated from the highest value obtained during three countermovement jumps performed on a force platform. HRV was analyzed from the interval heartbeats collected by a chest strap during the last three minutes of the 10-minute recovery period, with RMSSD and HF parameters calculated in the time and frequency domains, respectively. Blood lactate was measured at rest, after the test, and after recovery to calculate lactate clearance (LAclear), defined as the difference between post-test and post-recovery lactate levels. Autonomic-neuromuscular decoupling was quantified as DECRMSSD = z(ΔRSImod%) − z(ΔRMSSD), with within-subject z-scores computed across
RESULTS:
A linear mixed model showed DECRMSSD varied between recovery methods (LMM: Passive–Active = - 2.00, 95% CI- 3.02 to -0.99; F(1, 26) = 16.5, p<0.001), with higher DECRMSSD during active (EMM = +1.00, 95% CI 0.29-1.72) than passive recovery (EMM = -1.00, 95% CI -1.72 to -0.29). This was confirmed by a paired t-test (p = 0.013). Active recovery improved lactate clearance compared with passive recovery (t(13) = 5.48, p < 0.001). However, neuromuscular recovery (percentual difference of RSImod values between post recovery and rest periods) was not linked to vagal recovery indices (RMSSD: p = 0.762; HF: p = 0.968), and no condition vs. vagal index interactions were found (p ≥ 0.264).
CONCLUSION:
Active recovery enhanced metabolic recovery by increasing lactate clearance and altering the balance between neuromuscular and autonomic recovery, resulting in greater autonomic–neuromuscular decoupling than Passive recovery. However, short-term changes in vagal markers (RMSSD or HF) did not predict RSImod recovery, indicating an early disconnect between autonomic and neuromuscular recovery trajectories within 10 minutes after exhaustive running. These results emphasize that recovery methods can differentially affect physiological systems, and that metabolic improvements do not necessarily indicate that neuromuscular and autonomic recovery are synchronized immediately after maximal running exercise.