Precooling with an ice vest: Effect on core temperature in collegiate female swimmers

Abstract

Precooling has been shown to improve athletic performance, delay core heating, and decrease heartrate in cyclists and runners, but very little research has observed core temperature (CT), rate of perceived exertion (RPE) and heartrate (HR) response to precooling in collegiate female swimmers. Purpose: The purpose of the current study was to observe the effect of precooling on CT, RPE, and HR while swimming 1600-yards. Methods: Eleven female collegiate swimmers participated in randomized crossover swimming trials with and without precooling. Trials were separated by one week with each subsequent trial performed at the same time of day in the same pool and lane set-up with a water temperature of 26.1° C. Subjects rested for 30 min while wearing an ice vest and wet t-shirt in precooling trials. All trials included the same 15 minute warm up followed by 1600-yards at 75% of their individual fastest mile pace. CT, RPE and HR were recorded before and after warm up, and at 100-yard intervals. Results: Average group precooling CTs were significantly lower (37.88±4° C) than the control condition (38.17±.19° C, P=.02) throughout the test. Group precooling HRs were not significantly different (P=.20), however seven of the 11 subjects did present lower HRs during the precooling trial. Group RPEs were not significantly different between conditions (P>.05), although six subjects presented significantly higher RPEs in the precooling condition (P<.05). Conclusion: Precooling using an ice vest 45 min prior to exercise was shown to significantly reduce CT during swimming compared to no precooling. HR and RPE varied between subjects, suggesting that athletes respond differently both physiologically and psychologically to precooling. Coaches should consider individual variation and experiment prior to competition to determine whether precooling can improve performance in a 1600-yd swim.