Sequential associations among perceived heat-related symptoms, fatigue, and performance-related behavior during summer training.

Heat exposure during exercise is a physiological stressor that athletes perceive and that can influence subsequent behavior. This study examined the sequential relationships among perceived health factors, perceived heat-related symptoms (dizziness, headache, nausea, and malaise), and performance-related athletic behaviors during summer training in Japanese collegiate athletes. A paper-based survey conducted in 2015 at 11 Japanese universities yielded valid responses from 1322 male and 552 female athletes. The survey assessed perceived heat-related symptoms, perceived performance declines (strength, power, endurance, concentration, perceptual-cognitive skill, and motivation), athletic activity conditions (e.g., prolonged duration, insufficient rest or hydration, excessive heat or humidity, solar radiation, poor airflow, and clothing discomfort), and health-related factors (appetite loss, sleep deprivation, diarrhea, sickness, dehydration, fatigue, mental stress, and, in females, menstruation) during summer sports.). Structural equation modeling revealed that perceived heat and humidity, poor airflow, and clothing discomfort were associated with unfavorable activity conditions. These conditions were linked to worsening perceived health factors, including fatigue, illness, and mental stress, which were subsequently associated with perceived dehydration and appetite loss, indicative of body fluid imbalance. This imbalance was strongly associated with perceived heat-related symptoms (males: β=0.92, R2=0.85; females: β=0.77, R²=0.74) and perceived performance declines (males: β=0.42-0.53, R2=0.28-0.67; females: β=0.23-0.56, R²=0.38-0.40) (all p < 0.001). These findings suggest that impaired perceived health status is associated with both heat-related symptoms and declines in physical and cognitive performance during summer training. Monitoring athletes' perceived health status may support timely training adjustments in hot environments.