Author(s): KANATANI, K., NAKAGAWA, Y., XY, H., TAKAGI, T., KAWABATA, T., Institution: ENVIROMENT PHYSIOLOGY FOR EXERCISE, Country: JAPAN, Abstract-ID: 2551

INTRODUCTION:
It is important to prevent hyperthermia and heatstroke, and to control dangerous increases in body temperature in order to safely enjoy exercise and sports activities in hot enviroment. We have shown that brief (2minute) cryostimulation(whole body and lower limbs: -120°C, sole of the feet:-50°C) decrease of esophageal temperature during the recovery period after exercise in a hot environment. In this study, the effects of interval the soles of the feet cryostimulation during a football practice game in a hot environment were examined from exercise physiological and biomechanical perspectives.
METHODS:
Twenty-two subjects were selected into two groups: sole of the feet cryostimulation (SC) and a control (CON) group. Both groups participated in a football training session followed by three sets of 15-minute games with 10-minute breaks in between, in a temperature of approximately 32℃ and 45% relative humidity. After training and each game, the SC underwent cryostimulation(-50℃) on the soles of the feet for 2 minutes. Both groups were measured for body weight (BW) and Therm scale before and after training. After training, the tympanic temperature (Ttym) was measured. In the game session, measurements were taken for BW, Therm scale, and Ttym immediately after the game ended. And Ttym was also measured after 2 minutes end of the game. Continuous measurements were taken of running speed and distances and heart rate (HR). Water debt during exercise was calculated by multiplying body weight (in 10g units) by water consumption. The Thermal scale was used to measure 10 levels of subjective temperature sensation.
RESULTS:
Dehydration levels per training and per game increased with exercise duration, with slightly lower levels in the SC. There was no significant difference in Ttym compared to the CON. However, the SC showed a tendency to suppress the increase in Ttym. HR during the game showed an increase with each game in both groups. Post-training and post-game SC significantly suppressed the HR. Additionally, HR during exercise also showed a tendency to be suppressed compared to CON. Subjective thermal sensation was found to be suppressed in resting values due to the effect of the SC. There was no difference in the total running distance per game between the two groups in the SC and the CON. However, during the third game, the total distance covered at high speed running (HSR; < 20km/h) was higher in the SC(6.57 ± 1.66 m) compared to the CON(4.87 ± 0.77 m).
CONCLUSION:
It was found that cryostimulation of the sole of the foot suppresses dehydration and decreases Ttym and HR during exercise. Subjective thermal sensation was also suppressed. It is thought that cooling the arteriovenous anastomosis area (AVA) of the sole effectively returned venous blood that had dissipated heat. There was no difference in the total running distance between games 1, 2, and 3. However, it is worth noting that the SC maintained a significantly higher value of HSR distance in game 3 without any decrease. The Sole of the feet cryostimulation can be easily administered in the field and can suppress the rise in body temperature in a short time. This may be an effective measure to prevent heat stroke caused by environmental (physical) stress from the hot and humid summer environment and exercise (physiological) stress from physical exercise and sports.