Whole-body cryotherapy rebalances the sympathovagal activity both before and after a maximal exercise

Whole-body cryotherapy (WBC) is a short exposure to air below -100°C known to enhance the physical recovery and to reduce pain and perceived symptoms of muscle soreness (Rose et al, DOI: 10.1055/s-0043-114861). This practice seems to act on metabolism, inflammation, and tissue damage. Literature mainly studied WBC applied immediately after exercise, while no data are available on the net effect of WBC in the resting periods preceding and following the exercise. Hence, we evaluated the sympathovagal balance both before and after complete recovery from maximal exercise in naïve subjects; then the whole procedure was repeated after WBC (3 min, -100 to -150°C). ECG was recorded in 11 healthy men during rest, all-out exercise on a cycle ergometer (~30 s), and after recovery. R-R intervals were extracted and HR variability power was measured in the low and high frequency ranges (LF ~0.04-0.15 Hz; HF ~0.15-0.4 Hz) to estimate the sympathetic and the vagal activation, respectively. As expected, exercise reduced LF and, largely, HF, thus increasing LF/HF ratio up to ~2.5 times. In turn, WBC decreased LF/HF both at rest (from 2.01 to 1.53) and after exercise (from 5.37 to 3.53). Repeated measures ANOVA confirmed this finding with a frequency x exercise (p<0.003) and frequency x WBC interactions (p=0.047), with no three-way interaction. These results indicate that a single WBC session helps to rebalance the sympathovagal activity with an effect that persists even after a maximal exercise.