Whole-body cryotherapy boosts exercise performance by shifting the sympathovagal balance toward vagal predominance

Whole-body cryotherapy (WBC) is known to maximize physical recovery after intense exercise and to reduce the ensuing muscle damage, also by affecting the cardiovascular system. Considering the strong influence of autonomic nervous system on cardiovascular responses, we tested the effects of WBC on sympathovagal balance, as well as on Heart Rate (HR) recovery after exercise. ECG was recorded in 28 healthy adults who underwent rest, all-out effort on a cycloergometer, 5 min recovery and again rest. After 2-3 days, WBC (3 min, -150°C) was applied and the protocol repeated. Sympathovagal balance was evaluated by measuring HR variability power in the low (LF) and high (HF) frequency bands, both before exercise and after recovery. Sympathetic vs. vagal predominance was assessed by the index LFnu. Total exercise duration was split into the time needed to reach peak power (tPEAK) and the time to exhaustion (tEXH). The post-exercise exponential decay of HR was characterized by its delay from exercise end (tDELAY) and by its time constant (τOFF). ANOVA on HR variability confirmed that exercise shifted the sympathovagal balance towards sympathetic predominance, but it also highlighted that WBC enhanced vagal drive at rest, both before exercise and after recovery, covering ~70% of the exercise effect. In parallel, paired t-tests indicated that WBC increased tEXH and reduced tDELAY, speeding up HR recovery. This suggests that WBC may be exploited to boost exercise performance.