Thermal stress has been a concern for athletes during sporting events, especially in environments with a high ambient temperature and percentage of relative humidity. It was hypothesized that precooling may improve performance among athletes of sports with intermittent sprinting.
PURPOSE: To investigate the effects of a 20-minute part-body precooling on performance and physiological variables during an intermittent sprinting protocol (ISP) in a warm and humid environment.
METHODS: Ten male athletes (age: 24.60 ± 0.96 years) who participated in intermittent-sprinting sports were recruited and randomly assigned to either the control trial (CT) or experimental trial (ET). During ET, prior to warm up, a precooled towel dipped in ice was administered around their neck, covering both carotid arteries and a 0.5 kg ice pack was placed on each of the quadriceps muscle for 20 minutes. Warm up consisted of jogging 2 rounds around the hockey pitch, static stretches (quadriceps, hamstrings, groin and calves) and running 3 laps between the cones set at 20 metres apart. The ISP is a 20-minute test consisting of 4x5 minute sets of intermittent sprinting exercise with 2 minutes rest. Participants would sprint for 5 seconds followed by either hard running, jogging, walking, which is rotated every minute. Heart rate (HR), rate of perceived exertion (RPE), thermal scale sensation (TSS) and temperature were recorded across timepoint (TP) (after warm up, every 5 minutes during ISP, and 10 minutes after test).
RESULTS: There was significant improvement in total ISP distance covered between trials (ET: 2551.40 ± 177 m vs. CT: 2371.10 ± 216 m, p = 0.024). There was also a significant effect of precooling on core temperature across TP between trials, F(1, 9) = 15.12, p = 0.00). However, there were no significant differences across TP between trials for HR F(1, 9) = 2.10, p = 0.145), RPE F(1, 9) = 1.49, p = 0.246), TSS F(1, 9) = 2.66, p = 0.072). Moreover, there was no significant difference between pre- and post-trials for sweat loss (ET: 0.62 ± 0.16 kg vs. CT: 0.67 ± 0.24 kg, p = 0.177).
CONCLUSION: Smaller field-based precooling methods may improve performance during intermittent sprinting exercises. Athletes participating in sports with intermittent sprints may want to implement precooling method during trainings and competitions to improve performance.