Thermal imaging of cutaneous temperature modifications in runners during graded exercise

In this paper we used high-resolution thermal imaging to visualize the human whole body anterior cutaneous temperature (T(c)) variations in well-trained runners during graded exercise. Fifteen male volunteers underwent a graded treadmill test until reaching their individual maximal heart rate. Total body T(c) decreased as the subjects started the exercise. Thighs and forearms exhibited the earliest response. A further T(c) diminution occurred with the progress of the exercise. At the exercise interruption, T(c) values were in average 3-5 degrees C lower than at baseline. T(c) increased during recovery from exercise. Forearms and thighs exhibited the earliest increase, followed by total body T(c) increase. Thermal imaging documented the presence of hyperthermal spots (occasionally tree-shaped) due to the presence of muscle perforator vessels during baseline and recovery, but not during exercise. The results we report indicate that thermal infrared imaging permits the quantitative evaluation of specific cutaneous whole body thermal adaptations which occur during and after graded physical activity. Thus providing the basis for evaluating local and systemic cutaneous blood flow adaptation as a function of specific type, intensity and duration of exercise, and helping to determine the ideal conditions (in terms of environment and apparel) in which physical activities should be conducted in order to favor thermal regulatory processes.