Author(s): TOKUNAGA, K., YAMAMOTO, T., TSUNEMATSU, H., ABE, S., NAKASHIMA, S., KOMATSU, T., TANAKA, H., SHIRAISHI, A., MICHISHITA, R., SAKU, K., UEHARA, Y., Institution: FUKUOKA UNIVERSITY, Country: JAPAN, Abstract-ID: 2369

INTRODUCTION:
For athletes, maintaining daily training can be essential. Physical stress disrupts normal physiological balance or homeostasis, including the immune system, especially during high-intensity exercise. Natural killer (NK) cells, a type of immune cell, are sensitive to exercise, and a decrease in NK cell activity contributes to immune system dysfunction. Therefore, maintaining high NK cell activity after exercise is a key factor in improving long-term performance. Recently, it has been reported that maintaining deep muscle temperature with a heat-retaining function after exercise can improve performance. The aim of this study was to investigate the acute effects of wearing thermoretentive tights after high-intensity exercise on immune function.
METHODS:
Thirteen healthy adult males (21-29 years of age) participated in a randomized crossover study comparing conditions with and without heat-retaining tights (prototype of Thermal Charge®, Mizuno, Japan). The exercise protocol consisted of resistance training followed by high-intensity interval training (HIIT) on a bicycle ergometer. The effects on NK cell activity and heat shock protein 60 (HSP60) were assessed at baseline, 0, 30, and 150 minutes after exercise. A two-way ANOVA was performed, and when significant interactions were observed, trend analysis was performed for each group. A significance level of p < 0.05 was used.
RESULTS:
All 13 participants completed the exercise. The control group showed a significant decrease in blood NK cell activity from baseline to 150 minutes after high-intensity exercise. In contrast, there was no decrease in NK cell activity from baseline to 150 minutes post-exercise when wearing thermoretentive tights. In addition, a significant increase in blood heat shock protein 60 concentration was observed only when wearing thermal-keeping tights.
CONCLUSION:
Wearing thermal-keeping tights prevented the decline in serum NK cell activity at 150 minutes after high-intensity exercise and increased serum HSP60 levels after exercise. The thermoretentive garments used in this study have been shown to maintain both deep and superficial muscle temperature during exercise.
Thus, it is suggested that heat retention in deep muscles may have contributed to the suppression of immune decline.