Effects of whole-body cryotherapy on exercise performance and subsequent fast recovery

Purpose: Whole-body cryotherapy (WBC) has been reported to maximize physical recovery after intense exercise and reduce muscle damage. In addition, as exercise, also WBC affects the cardiovascular system. Considering the strong influence of the autonomic nervous system on cardiovascular responses, we sundered the effects of WBC and exercise regards to i) sympathovagal balance assessment; and ii) successive R-waves on the electrocardiogram (RR interval) before and after the exercise protocol. Methods: ECG was recorded in 28 healthy adults who underwent rest (5 min), all-out effort on a cycle ergometer (~30 s), and following recovery (5 min). After 30 days, WBC (3 min, -150°C) was applied, and the whole procedure was repeated. Sympathovagal balance was evaluated by measuring HR variability power in the low and high-frequency bands and by time domain (RR interval and the root mean square of successive differences between normal heartbeats, lnRRMSSD) before and after exercise. These parameters were evaluated in ultra-short-term steady rest and recovery phases (3 min). Total exercise duration was split into the time needed to reach peak power output (tPEAK) and the time to exhaustion (tEXH). The post-exercise exponential decay of HR was characterized by its delay from exercise cessation (tDELAY) and by its time constant (tOFF). Results: ANOVA on HR parameters confirmed that exercise and WBC treatment changed HR and RR values in specific conditions. In both situations, exercise significantly lowered RR interval (p<0.001) while increased HR (p<0.0001). In analogous, the WBC treatment increased RR interval and diminished HR only at rest (724 ms to 765 ms, p=0.023; and 85.1 to 80.6 bpm, p=0.03; respectively) without changes in the recovery phase. From the autonomic nervous standpoint, both lnRMSSD and lnLF/HF did not change in rest and recovery phases influenced by WBC (p>0.05). In contrast, the exercise reduced only the lnRMSSD in control and WBC situations (p<0.001) without changes in lnLF/HF (p>0.05). In parallel, paired t-tests indicated that WBC increased tEXH (p=0.0122), keeping a similar tPEAK (p>0.05) but reducing tDELAY (p=0.0027) following the exercise, which may be corresponded to speeding up the HR recovery but without significant reductions on tOFF. Conclusions: This suggests that WBC may be exploited to boost exercise performance and its fast recovery (lower tDELAY) by improving the readiness before exercise. However, these changes did not reflect a more immediate vagal reactivation after exercise. References: Costello JT, Donnelly AE, Karki A, Selfe JN. (2014) Effects of whole-body cryotherapy and cold-water immersion on knee skin temperature. Int J Sports Med 35: 35-40. Storniolo JL, Esposti R, Cavallari P. (2020) Heart rate kinetics and sympatho-vagal balance accompanying a maximal sprint test. Front Psychol 10:2950.