RESUMEN
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.
RESUMEN
OBJECTIVES: Conduct a comprehensive epidemiological study of match injury characteristics (incidence, severity, causes, diagnostics, and temporal trends) in professional rugby league. DESIGN: Prospective cohort design. METHODS: Data was captured over the 2013, '14, and '15 seasons, collected via an online-reporting survey tool, and underpinned by nominal group technique-agreed definitions. Injury details were provided by club medical staff in accordance to the survey fields from all European Super League teams (e.g. injury occurrence/return dates, diagnosis, mechanism, recurrence). All time-loss injuries have been reported. RESULTS: Injury incidence of 57 injuries/1000h has been observed over the three-year period, with an average of 34days missed per injury. The final 20-min period was the most significant period for injury occurrence, and higher incidence of injury/1000h played was during the start of the season in February, although an absolute injury risk for injury frequency was shown in April due to the greatest playing time. Forward positions reported the highest injury incidence whilst tackle activities were the most frequent mechanism of injury. Concussions and hamstring strains (5 injuries/1000h) were the most commonly diagnosed injuries, although the knee joint region (10 injuries/1000h) was the most frequently injured area. CONCLUSIONS: In light of the most common injury diagnoses, mechanisms, identified seasonal risk, and time of match, the data should look to inform player preparation in terms of physical conditioning and tackle technique in order to optimise player welfare and availability for participation.