Effects of cold-water immersion after rugby-specific training on endurance performance.

Time to exhaustion and V̇O2peak did not differ significantly between Control and CWI trials in absolute terms.

• Time to exhaustion was 485±72 s (Control) vs. 518±77 s (CWI), P=0.107, Cohen's d=0.45.
• The difference was not statistically significant at the conventional threshold.
• V̇O2peak also did not differ between the two conditions.
• Eleven healthy male collegiate rugby players participated in the study.

Relative changes in time to exhaustion and V̇O2peak from baseline (Pre) were significantly greater in the CWI trial than in the Control trial.

• Both relative change comparisons reached statistical significance (P<0.05).
• This suggests that CWI attenuated the decline in, or improved, endurance performance relative to pre-training baseline compared to seated rest.
• Effect size for time to exhaustion was d=0.45, indicating a small-to-medium effect.

CWI was performed for 8 minutes at 15°C immediately following a 180-minute standardized rugby-specific training session.

• The training session included warm-up, skill-based passing, contact drills, individual training (conversion kicking and scrummaging), and a bronco endurance test.
• The control condition consisted of 8 minutes of seated rest.
• Interventions were assigned in randomized order using a crossover design.
• The incremental cycling test was performed 24 hours after each recovery intervention.

Training load during the rugby-specific training session did not differ between the CWI and Control trials.

• Training load was assessed using heart rate-based training load and blood lactate concentrations.
• No significant differences were found between trials for these measures.
• This indicates that the training stimulus was equivalent before each recovery intervention, supporting the validity of the comparison.

Oxygen uptake, minute ventilation, and rating of perceived exertion during submaximal exercise were similar across the Pre, Control, and CWI trials.

• No significant differences were observed in these submaximal physiological and perceptual variables among the three conditions.
• This suggests CWI did not alter submaximal exercise economy or perceived effort.
• The incremental cycling test was used to assess these variables at baseline (Pre) and 24 h after each intervention.

The authors acknowledged that an expectancy or placebo effect of water immersion on exercise performance could not be excluded.

• The study design did not include a thermoneutral water immersion control to blind participants to the temperature condition.
• This limitation is explicitly noted in the abstract and represents a common methodological challenge in CWI research.
• The authors stated: 'the expectancy/placebo effect of water immersion on exercise performance could not be excluded.'