Spinal Manipulative Therapy Effects in Autonomic Regulation and Exercise Performance in Recreational Healthy Athletes: A Randomized Controlled Trial

Abstract

Objective. To analyse the acute effects of spinal manipulative therapy (SMT) on performance and autonomic modulation.

Summary of Background Data. The use of SMT is progressively spreading from the clinical to the sporting context owing to its purported ergogenic effects. However, its effects remain unclear.

Methods. . 37 male recreational athletes (aged 37 ± 9 years) who had never received SMT were assigned to a sham (n = 19) or actual SMT group (n = 18). Study endpoints included autonomic modulation (heart rate variability), handgrip strength, jumping ability and cycling performance (8-minute time trial [TT]). Differences in custom effects between interventions were determined using magnitude-based inferences.

Results. A significant and very likely lower value of a marker of sympathetic modulation, the stress score, was observed in response to actual compared to sham SMT (p = 0.007; effect size [ES] = -0.97). A trend towards a significant and likely lower sympathetic:parasympathetic ratio (p = 0.055; ES = -0.96) and a likely higher natural logarithm of the root-mean-square differences of successive heartbeat intervals ([LnRMSSD], p = 0.12; ES = 0.36) was also found with actual SMT. Moreover, a significantly lower mean power output was observed during the TT with actual compared with sham SMT (p = 0.035; ES = -0.28). Non-significant (p > 0.05) and unclear or likely trivial differences (ES < 0.2) were found for the rest of endpoints, including handgrip strength, heart rate during the TT, and jump loss thereafter.

Conclusion. A single pre-exercise SMT session induced an acute shift towards parasympathetic dominance and slightly impaired performance in recreational healthy athletes.