Purpose: Cold environments may deteriorate psychomotor performance due to slowing of neuronal signals, distractions caused by pain and discomfort, and a loss of manual dexterity. The extent to which core temperature (Tc) influences psychomotor performance in the cold has not been established. Therefore, psychomotor performance and Tc were assessed during a cold weather military training exercise to evaluate this relationship.

Methods: Thirty-six military personnel (age: 26 ± 4 yr, ht: 175 ± 8 cm, wt: 79.1 ± 11.1 kg) participating in cold weather training volunteered for this study. Participants completed a 10-min immersion in cold (1°C) water, followed by 60 min of rewarming. Physiological, perceptual, and psychomotor assessments were made throughout the training. For analysis, participants were divided into groups based on their lowest achieved core temperature (< 35.0°C = HYP; 35.0-36.0°C = CS-M; > 36.0°C = CS-S). Psychomotor performance was then compared among the groups to determine the influence of Tc on performance.

Results: Although cold water immersion deteriorated performance, no differences were observed among the three groups at any time point during the training for simple reaction time (HYP: 298 ± 49 ms; CS-M: 313 ± 55 ms; CS-S: 326 ± 53ms; p = 0.677).

Conclusion: Findings suggest that cold water immersion deteriorates psychomotor performance which, even in the presence of mild hypothermia, is not directly influenced by Tc. Additional observations reveal large variations in Tc among a homogenous group in response to cold water immersion.