The use of whole-body cryotherapy: time- and dose-response investigation on circulating blood catecholamines and heart rate variability

Abstract

Purpose: A predominance of parasympathetic drive is observed following cold exposure. Such modulation of the autonomic nervous system (ANS) is associated with faster post-exercise recovery. Within this context, whole-body cryotherapy (WBC) has been spreading in sport medicine, though the optimal temperature and frequency are unclear. The aim of this study was to examine the effects of different cryotherapy conditions on the sympathovagal balance.

Methods: Forty healthy males were randomly assigned into five different groups (- 110 °C, - 60 °C, - 10 °C, control temperature [≃ 24 °C]) and undertook 5 WBC sessions over 5 consecutive days. Cardiac autonomic activity was assessed through heart rate variability (HRV) using power density of high frequency (HF), root-mean square difference of successive R-R intervals (RMSSD) and sympathovagal balance (LF/HF). Systemic sympathetic activity was assessed via circulating blood catecholamines.

Results: Mean weekly RMSSD (pre: 48 ± 22 ms, post: 68 ± 29 ms) and HF (pre: 607 ± 692 ms², post: 1271 ± 1180 ms²) increased (p < 0.05) from pre to post WBC, only in the - 110 °C condition. A rise in plasma norepinephrine was found after the first - 110 °C WBC session only (pre: 173 ± 98, post: 352 ± 231 ng L^-1, p < 0.01); whereas, it was not significant after the 5th session (pre: 161 ± 120, post: 293 ± 245 ng L^-1, p = 0.15).

Conclusion: These results suggest that one - 110 °C WBC exposure is required to stimulate the ANS. After five daily exposures, a lower autonomic response was recorded compared to day one, therefore suggesting the development of physiological habituation to WBC.

Keywords: Autonomic nervous system; Body temperature; Cryostimulation.

Fig. 1

Study design. HR heart rate, HRV heart rate variability, WBC whole-body cryotherapy

Fig. 2

Mean and SD values of tympanic (a) and skin temperature (c) of the whole body before (Pre), immediately after (Post) and for 20 min (P1–P20) after a whole-body cryotherapy (WBC) session at − 10 °C, − 60 °C, − 110 °C, and in the control condition (CONT). Values are means obtained for 5 WBC sessions. *Significantly (p < 0.05) different from Pre;# Significantly (p < 0.05) different from CONT. The magnitude of change (Hedge’s g) from pre for tympanic (b) and skin temperature (d). Horizontal dashed lines correspond to very small (< 0.2), small (0.2 < ES < 0.5), moderate (0.5 < ES < 0.8), large (0.8 < ES < 1.2) effects

Fig. 3

Mean and SD values of thermal (a) and comfort (c) sensation scores recorded before (pre), immediately (Post), 5 min (P5), and 20 min (P20) after a whole-body cryotherapy (WBC) session at − 10 °C, − 60 °C, − 110 °C, and in the control condition (CONT). Values are means obtained for 5 WBC sessions. *Significantly (p < 0.05) different from pre;# Significantly (p < 0.05) different from CONT. The magnitude of change (Hedge’s g) from pre for thermal (b) and comfort sensation (d). Horizontal dashed lines correspond to very small (< 0.2), small (0.2 < ES < 0.5), moderate (0.5 < ES < 0.8), large (0.8 < ES < 1.2) effects

Fig. 4

Magnitude of changes (Hedge’s g) from pre values for systolic (a) and diastolic (b) pressure and for heart rate (c) at day 1, day 5 and for mean weekly values. Horizontal dashed lines correspond to very small (< 0.2), small (0.2 < ES < 0.5), moderate (0.5 < ES < 0.8), large (0.8 < ES < 1.2) effects

Fig. 5

Magnitude of changes (Hedge’s g) from pre values for RMSSD (a), HF (b) epinephrine (c) and norepinephrine (d) at day 1, day 5 and for mean weekly values. Horizontal dashed lines correspond to very small (< 0.2), small (0.2 < ES < 0.5), moderate (0.5 < ES < 0.8), large (0.8 < ES < 1.2) effects