Palm Cooling Delays Fatigue during High-Intensity Bench Press Exercise

Local cooling can induce an ergogenic effect during a short-term intense exercise. One proposed method of personal cooling involves heat extraction from the palm. In this study, we hypothesized that local palm cooling (PC) during rest intervals between progressive weight training sets will increase total repetitions and exercise volume in resistance-trained subjects exercising in a thermoneutral (TN) environment. Sixteen male subjects (mean +/- SD; age = 26 +/- 6 yr, height = 178 +/- 7 cm, body mass = 81.5 +/- 11.3 kg, one-repetition maximum (1RM) bench press = 123.5 +/- 12.6 kg, weight training experience = 10 +/- 6 yr) performed four sets of 85% 1RM bench press exercise to fatigue, with 3-min rest intervals. Exercise trials were performed in a counterbalanced order for 3 d, separated by at least 3 d: TN, palm heating (PH), and PC. Heating and cooling were applied by placing the hand in a device called the rapid thermal exchanger, set to 45 degrees C for heating or 10 degrees C for cooling. This device heats or cools the palm while negative pressure (-35 to -45 mm Hg) is applied around the hand. Total exercise volume during the four PC sets (2480 +/- 636 kg) was significantly higher than that during TN (1972 +/- 632 kg) and PH sets (2156 +/- 668 kg, P < 0.01). The RMS of the surface EMG with PC exercise was higher (P < 0.01), whereas esophageal temperature (P < 0.05) and RPE (P < 0.05) were lower during PC compared with TN and PH. PC from 35 degrees C to 20 degrees C temporarily overrides fatigue mechanism(s) during intense intermittent resistance exercise. The mechanisms for this ergogenic function remain unknown.