Thermographic assessment three intensity training in healthy subjects

Introduction: Several studies showed exercise-related temperature changes in both muscle and skin by direct measurement Aim: It was hypothesized that the three very distinct, but isocaloric, exercise sessions of either INC, INT or CONT would increase temperature in an intensity dependent manner in healthy subjects. Methods: Eight healthy (4 male) participated in this study. Each of the 8 volunteers participated in 3 trials (INC, INT, and CONT) with one week between each trial and the starting trial was randomized. The INT was performed on a treadmill and consisted of 4 intervals of 4 min at an intensity that yielded 85–95 % of HRmax. Between the intervals, the subjects performed 4 min of active recovery at 50–60% of HRmax. To achieve an isocaloric protocol, INC involved incremental test for 20-30 minutes on the treadmill at 85-95% of HRmax and CONT involved walking continuously for 30-45 minutes on the treadmill at 60–70% of HRmax. The skin temperature of the anterior tibial muscle, gastrocsoleus muscle and achilles tendon (right and left) conventionally called "region of interest" (ROI), were measured by infrared thermography on before exercise, and during the 5-min and 10-min period post-trials. For each individual subject, repeated tests were performed at the same time of day. Results: nitial skin temperature was similar at before exercise in all trials, but after the CONT training skin temperature decreased both in the anterior tibial muscle as in the gastrocsoleus muscle. In contrast, achilles tendon temperature in the three trials remained elevated following the 5-min and 10-min period post-trials (p<0.05) Conclusion: These findings reveal a clinically relevant changed effect of acute exercise upon the skin temperature that is clearly exercise intensity dependent.