Effect of cold water immersion on 100-m sprint performance in well-trained swimmers

The aim of the present study was to examine the effect of cold water immersion (CWI) on sprint swimming performance in simulated competition conditions. Ten well-trained swimmers (5 males, 5 females; 19.0 ± 3.9 years) performed two 100-m swimming sprints (S1 and S2) interspersed with a 30-min passive recovery period, during which athletes were randomly assigned to 5 min of CWI (14°C) or an out-of-water control condition (CON 28°C). During tests, sprint times, heart rate (HR), pre- and post-race parasympathetic activity via HR variability (natural logarithm of the square root of the mean of the sum of the squares of differences between adjacent normal R–R intervals; Ln rMSSD) and blood lactate accumulation (La]_ac) and clearance (La]_cle) were recorded. Rates of perceived recovery (RPR) and exertion (RPE) were evaluated before and after each sprint. CWI was associated with a ‘likely’ decrease in swimming performance 1.8% (90% CI 0.2, 3.5)], as well as ‘likely’ lower peak HR −1.9% (−3.6, −0.2)]. CWI was also associated with a ‘likely’ smaller decrease in Ln rMSSD after the first sprint −16.7% (−30.9, −4.1)]. RPR was ‘likely’ better +27.2% (−3.7, 68.0)] following CWI. ‘unclear’ effects were observed for La]_ac +24.7% (−13.4, 79.5)], La]_cle −7.6% (−24.2, 12.7)] or RPE +2.0% (−12.3, 18.5)]. Following CWI, changes in sprint times were ‘largely’ correlated with changes in peak HR (r = 0.80). Despite a subjective perception of improved recovery following CWI, this recovery intervention resulted in slower swimming times in well-trained athletes swimming in simulated competition conditions.