Optimizing Cognitive And Exercise Performance In Hot Conditions

PURPOSE: Balance of physical and mental performance is critical for military mission readiness. High mental acuity in challenging conditions is necessary for achieving mission objectives. As the global climate warms, thermal management is crucial in mission planning. This study examines if managing heat strain enhances cognitive performance during exercise in a controlled heat stress environment.

MATERIALS AND METHODS: Eighteen healthy male subjects participated in two counterbalanced two-hour exercise sessions, exercising at 75% of maximum heart rate (HR) or maintaining a physiological strain index (PSI) below 6. Cognitive performance was assessed using Stroop Color and Word (SCWT) and N-back (N = 2) tests at 15-minute intervals. Subjects made three lab visits. In the first visit, subjects completed cognitive tests 12 times for familiarization. In subsequent visits, subjects did pre-exercise cognitive assessments followed by exercise trials paced by HR or PSI. The exercise trial involved a loaded (13.6 kg) two-hour run on a treadmill at 1% grade in a heat chamber (35 °C; 40% relative humidity), with cognitive tests during exercise conducted at 15-minute intervals. We hypothesized individuals’ performance on cognitive tasks would increase under the PSI condition compared to the HR condition.

RESULTS: SCWT scores showed no significant difference between HR and PSI conditions (34.31 ± 6.92 and 32.68 ± 5.93; p = 0.12). However, N-back test scores were significantly higher in the PSI condition (23.42 ± 10.04) compared to the HR condition (18.58 ± 13.22; p = 0.03).

CONCLUSIONS: PSI-guided pacing enhances working memory during exercise in a hot environment without affecting the ability to ignore cognitive interference. These results highlight the benefits of physiological feedback in optimizing cognitive function under thermal stress, emphasizing the importance of integrating heat strain management into training protocols for sustained performance in demanding conditions. Future research will explore underlying physiological mechanisms and optimize thermal management strategies across diverse operations.