Endurance and intermittent exercise performance are impaired by high ambient temperatures. Various countermeasures are considered to prevent the decline in exercise performance in the heat, convenient, and practical cooling strategies attracts attention. The purpose of this study was to investigate the effect of wearing a new type of cooling vest which cooled torso and neck during half-time (HT) on intermittent exercise performance that imitated intermittent athletic games. All measurements on the experiments were carried out with the bicycle ergometer. Eight male soccer players performed a familiarization session and two experimental trials of a 2 × 30 min intermittent cycling exercise protocol, which consisted of a 5 s maximal power pedaling (body weight ×0.075 kp) every minutes separated by 25 s unloaded pedaling (80 rpm) and rest (30 s) in the heat (33.0°C; 50% relative humidity). The two trials included cooling-vest condition (VEST) and control condition (CON), and the difference is with or without wearing cooling vest imposed for 15 min at HT. Mean and peak power output, rectal (Tre) and skin temperature (neck, upper back, chest, right upper arm, and thigh), heart rate (HR), deep thigh temperature, rating of perceived exertion (RPE), and thermal comfort (TC) and thermal sensation (TS) were measured. Mean power output at 2nd half was significantly greater ( p < 0.05) in VEST (3rd trial: 589 ± 58 W, 4th trial: 584 ± 58 W) than in CON (3rd trial: 561 ± 53 W, 4th trial: 561 ± 53 W). HR were significantly lower in VEST during HT and higher in VEST at the last maximal pedaling ( p < 0.05). At the end of HT, neck skin temperature and mean skin temperature were significantly lower in VEST (32.04 ± 1.47°C, 33.76 ± 1.08°C, respectively) than in CON (36.69 ± 0.78°C, 36.14 ± 0.67°C, respectively) ( p < 0.05). During 2nd half, TS, TC, and RPE were significantly lower in VEST than in CON ( p < 0.05). There was no significant difference in Tre and deep thigh temperature throughout each conditions. These results indicate that wearing a new type of cooling vest during HT significantly improves intermittent exercise performance in the heat with decreased neck and mean skin temperature and improved subjective responses.

Intermittent exercise performance in a hot environment is lower than in temperate conditions. Cooling strategies at rest are important; however, the appropriate cooling temperature is not clear. The purpose of this study was to investigate the effect of temperature for cooling leg during half-time (HT) on intermittent exercise performance. Eleven men performed two pre-tests and three experimental trials of a 2 × 30 min intermittent exercise protocol in the heat (33°C; 50% relative humidity). During HT, three experimental conditions were set: no cooling (CON), cooling at the thigh using 12°C ice packs (COOL), and cooling at the thigh using 0°C ice packs (ICE) for 15 min. During the 2nd half, which consisted of 5 s maximal power pedaling every minute separated by 50 s of unloaded pedaling (80 rpm) and rest (5 s), the subjects repeated 2 × 15 sets of the intermittent exercise protocol. The peak power output under the COOL condition (694 ± 80 W) was significantly higher than that of the CON (653 ± 84 W). Thigh skin and deep temperatures showed a significant difference between each condition. In the COOL, thermal sensation was significantly lower, and thermal comfort was significantly higher. In a protocol that simulates intermittent athletic competitions such as soccer in a hot environment, using ice packs at 12°C to cool the thigh during HT lowered thigh skin and deep temperatures and improved heat perception and intermittent exercise performance. This cooling strategy is practical, suggesting that it would be effective for actual competitive situations.

The present study aimed to investigate the effect of cold water immersion of the hand and forearm during half-time (HT) on intermittent exercise performance and thermoregulation by imitating intermittent athletic games in the heat. In a randomized crossover design, 11 physically active men performed the first half (first and second block) and second half (third and fourth block) intermittent cycling exercise protocol, which consisted of a 5-s maximal power pedalling (body weight × 0.075 kp) every minute separated by 25-s of unloaded pedalling and rest (30 s) in the heat (33°C, 50% relative humidity). The two-halves were separated by a 15-min HT. During HT, the participants were assigned to the CON (sedentary resting) or COOL (immersion of hands and forearms in cold water at 15–17°C) condition. The mean power output in the second half was significantly greater (third and fourth block: p &lt; 0.05) in the COOL than in the CON condition. Moreover, there was a significant decrease in the rectal (0.54 ± 0.17°C, p &lt; 0.001) and mean skin (1.86 ± 0.34°C, p &lt; 0.05) temperatures of the COOL condition during HT. Furthermore, the heart rate (16 ± 7 bpm, p &lt; 0.05) and skin blood flow (40.2 ± 10.5%, p &lt; 0.001) decreased at the end of HT in the COOL condition. In the second half, thermal sensation was more comfortable in the COOL condition (p &lt; 0.001). Cold water immersion of the hand and forearm during HT improved physiological and reduced perceived heat stress. Moreover, it prevented a reduction in intermittent exercise performance in the second half.