Effects of treatment dosage of whole‐body cryotherapy upon post‐match recovery of endocrine and biochemical markers in elite rugby league players: An experimental study

Background and Aims: The use of whole‐body cryotherapy (WBC) for athletic recovery is becoming increasingly popular despite the lack of evidence supporting the dosage parameters in its implementation. The aim of the current study was to investigate the dose–response effects of WBC following match‐play in elite rugby league players. Methods: We observed endocrine (salivary cortisol and testosterone) and biochemical (creatine kinase) responses following three separate post‐match recovery periods in elite rugby league players. Comparisons were made between a single exposure (3 min at −120°C to ‐−135°C) of WBC to two consecutive exposures (2 × 3 min), to a control (no exposure) during the recovery trials. Recovery characteristics were measured 36 h prematch, immediately postmatch, and 60 h postmatch. Results: Cortisol concentrations remained unchanged in its pattern of response during the postmatch recovery periods across all WBC doses. Testosterone concentrations increased significantly (p < 0.0005) at 60 h, in the WBC2 trial. The Testosterone:Cortisol ratio increased significantly (p < 0.0005) at 60 h in the WBC2 trial, while during the WBC0 trial it did not recover to baseline levels. No significant effect on creatine kinase concentration was observed, although a statistical trend was shown in WBC2 for improved reduction of this marker at 60 h. Conclusions: These findings suggest that two, consecutive exposures to WBC immediately following fatiguing rugby league competition appear to stimulate an increase to the anabolic endocrine profile of participants by 60 h post‐match, and may reduce the CK concentration. Coaches and athletes should consider the treatment dosage of WBC when used to optimize the desired response following a high‐stress environment.