Skin temperature modifications during physical exercise measured by infrared thermography

Heat dissipation during sport exercise is an important physiological mechanism that may affect athletic performance. It depends on skin temperature (ST) and on cutaneous blood flow (CBF). ST, as an indicator of CBF, can be measured by infrared thermography (IRT). ST modifications during different kinds of exercise have been studied by few researchers using IRT. Global endurance exercise, such as graded load running, was characterized by a decrease in the ST of the all body (Merla et al., 2010); similar results was also found in incremental cycling exercise where the ST of the trunk (Torii et al., 1992) and of the finger of the hand (Zontak et al., 1998) begun to fall immediately on starting to exercise. Different ST trend was found in exercise involving only small muscle groups. In a localized resistance physical exercise it was observed a little increase in ST of the posterior thigh (Ferreira et al., 2008) and of the deltoid after static exertion until exhaustion (Bertmaring et al., 2008). Also breathing exercises were evaluated using IRT: it was found a different dynamics of ST changes in diaphragmatic and thoracic respiration. In diaphragmatic exercise, which mainly uses internal musculature, as compared to thoracic one, temperature did not increase in trunk areas. This is probably due to a lesser use of superficial muscle (Ludwig et al., 2012). A recent study put in evidence that trained subjects responded more quickly than untrained controls in standing calf raise exercise (Formenti et al., 2013). A possible explanation may be found in the different grade of vasoconstriction in trained and untrained subjects that occur in the beginning of the exercise. In a new study that we are performing, we would to test the hypothesis that differences in ST trend exist in two modalities of squat exercise: normal velocity of movement (1 sec. eccentric/1 sec. concentric phase) and slow velocity of movement (5 sec. eccentric/5 sec. concentric phase) that should cause more vasoconstriction in the quadriceps. Medical thermal images are captured in several modes that can be classified according to the temporal rate of shooting. Single state image enhance areas of the body with hot and cold spots. Temporal sequences of thermal images can be helpful to detect thermal anomalies linked to different pathologies and during exercise. With very fast image shooting (100 hz.) it is possible to detect variations in temperature arise from hemodynamic or neural control. Because of the difficult in recording and analyzing thermal images, the methods by researchers are not similar with the others. Thus, further studies are necessary to standardize the methods both in thermal images analysis and protocol procedure, as well as applying IRT to other kind of physical exercises and subjects. Bibliography Bertmaring et al., Ergonomics. 2008, 51, 1606-1619. Ferreira et al., Ann. Biomed. Eng. 2008, 37, 1420-1427. Formenti et al., Ann. Biomed. Eng. 2013, 41, 863-871. Ludwig et al., Acta Bioeng. Biomech. 2012, 14, 41-47. Merla et al., Ann. Biomed. Eng. 2010, 38, 158-63. Torii et al., Br. J. Sports. Med. 1992, 26, 29-32. Zontak et al., Ann. Biomed. Eng. 1998, 26, 988-993.