Francisco Tavares, Martyn Beaven, Júlia Teles, Dane Baker, Phil Healey, Tiaki B Smith, Matthew Driller

While the acute effects of cold water immersion (CWI) have been widely investigated, research analysing the effects of CWI over a chronic period in highly-trained athletes is scarce. The aim of this study was to investigate the effects of CWI during an intense three week pre-season phase in elite rugby athletes. Twenty-three elite male rugby union athletes were randomized to either CWI (10 min at 10 ºC, n = 10) or a passive recovery control (CON, n = 12) during three-weeks of high volume training. Athletes were exposed to either CWI or CON, after each training day (12 days in total). Running loads, conditioning and gym sessions were kept the same between groups. Measures of countermovement jump (CMJ), perceived muscle soreness and wellness were obtained twice a week, and saliva samples for determining cortisol and interleukin-6 (IL-6) were collected once per week. Although no significant differences were observed between CWI and CON for any measure, CWI resulted in lower fatigue markers throughout the study, as demonstrated by the moderate effects on muscle soreness (d = 0.58 to 0.91) and IL-6 (d = -0.83), and the small effects (d = 0.23 to 0.38) on CMJ in comparison to CON. The results from this study demonstrate that CWI may provide some beneficial effect by reducing fatigue and soreness during an intense three week training phase in elite rugby athletes.