Effects of a phase change cooling garment during exercise in the heat

The purpose of our study was to examine the physiological, perceptual, and performance effects of wearing a phase change cooling garment (CG) during an interval exercise routine in the heat. Sixteen male participants (age 23 +/- 3 years, ht 1.76 +/- 0.11m; wt 78.5 +/- 11.2kg; body fat 15.2 +/- 5.8%) completed two trials (one with phase change inserts, CG, and one control without inserts) consisting of two submaximal exercise portions separated by 5-minute seated rest, and a final maximal effort performance bout. Each submaximal bout involved 30seconds or 1minute of muscular endurance and agility exercises and 5minutes of treadmill jogging and step-ups. The performance bout included 30seconds or 1minute of muscular endurance and agility exercises, with participants completing as many repetitions as possible, followed by a 15-minute recovery (active and passive). Rectal temperature (T-re) and heart rate were not different between trials, however change in T-re from baseline was improved during 10 and 15 minutes of recovery with the CG (P<.05). Mean skin temperature was lower using the CG vs control throughout the trial (P<.05). Thermal sensation was lower when using the CG compared to control (P<.001). There were no differences in any outcomes of the performance exercises (P>.05). These findings indicate that the continuous use of a CG during an interval style workout in the heat provides improvements in thermal sensation, however, only minimal thermophysiological benefits, and no performance augmentation.