Comparison of cutaneous termic response to a standardised warm up in trained and untrained individuals

Aim. Warm up prior to exercise induces an increased production of metabolic heat, which triggers the thermoregulatory system to initiate heat loss mechanisms. Variations in cutaneous tissue temperature have been already reported in trained subjects, by means of high resolution thermal imaging. Purpose of this paper was to quantitatively evaluate, by means of infrared thermography, the differences in the cutaneous temperature among trained and untrained subjects. Methods. Forty male volunteers performed a standard warm up exercise on a stationary cycle, divided in three steps: 1) 0-5 minutes at 100 Watt; 2) 5-10 minutes at 130 Watt; and 3) 10-15 minutes at 160 Watt Thermal images from thorax and upper limbs were collected during the exercise. Heart rate was also measured. Results. In comparison to baseline, trained subjects exhibited a significant temperature reduction in the third step (trunk, P<0.01 ; upper limbs, P<0.009), while no difference was observed in untrained subjects. In the comparison between groups, a statistically significant difference was observed in both regions of interest, in the second (trunk, P<0.01; upper limbs, P<0.02), and in the third step (trunk, P<0.0002; upper limbs, P<0.0008). During the whole exercise, heart rate increased progressively in all participants, but more markedly in untrained subjects. Conclusion. Cutaneous thermoregulatory response differs among trained and untrained participants. Infrared thermal imaging is useful in detecting these differences, providing additional data to the physiological evaluation of subjects performing sport activities.