Impact of Body Cooling and Mental Fatigue on Endurance Performance: New Research Findings

Endurance sports such as long-distance running, cycling, and cross-country skiing demand sustained physical effort over extended periods, influenced by multiple environmental and psychological factors. Recent research highlights how cold temperatures and mental fatigue can impair athletic performance, especially when combined.

Studies show that in moderate cold conditions around 10°C (50°F), endurance performance may improve under certain circumstances. However, extreme cold can hinder muscle and nerve function, resulting in decreased efficiency and performance decline. Such reactions are believed to involve the sympathetic adrenal-medullary (SAM) stress response system.

Concurrently, mental fatigue—often caused by psychological stressors—has been shown to reduce motivation and elevate feelings of fatigue, further impairing performance. In hot environments, mental exhaustion appears to influence performance through the hypothalamic-pituitary-adrenal (HPA) axis, another stress pathway.

Despite these insights, the interaction between cold exposure and mental fatigue remained poorly understood until recently. A study led by Associate Professor Daiki Imai at Osaka Metropolitan University's Research Center for Urban Health and Sports investigated this interplay. The research involved nine healthy young men who underwent mental fatigue induction through Stroop color-word tasks while wearing cooling suits to lower their whole-body temperature. Researchers assessed their endurance during exercise, paying close attention to subjective fatigue and the body's stress responses.

The findings, published in the European Journal of Applied Physiology, indicated no overall difference in endurance performance across conditions. However, individual variations were significant—participants reporting higher subjective fatigue experienced notably reduced endurance. The results suggested that the SAM stress response system, rather than the HPA axis, played a more pivotal role in fatigue associated with cold and mental stress.

Professor Imai emphasized the practical implications: "Our study offers a scientific basis to develop more effective conditioning strategies for winter sports and activities in cold environments." Future research aims to refine methods to mitigate cold and mental fatigue effects and identify individuals more susceptible to these stressors.

This research underscores the importance of managing psychological and environmental stressors to optimize endurance performance in challenging conditions.