Thermography Applied During Exercises With or Without Infrared Light-Emitting Diode Irradiation: Individual and Comparative Analysis

Objective: The aim of our study was to evaluate the cutaneous temperature during an exercise on a treadmill with or without infrared light-emitting diode (LED) irradiation in postmenopausal women. Background data: Thermography is an imaging technique in which radiation emitted by a body in the middle and far infrared spectrum is detected and associated with the temperature of the body's surface. Materials and methods: Eighteen postmenopausal women were randomly divided into two groups: (1) the LED group, which performed the exercises on a treadmill associated with phototherapy (n = 9) and; (2) the exercise group, which performed the exercises on a treadmill without additional phototherapy (n = 9). The irradiation parameters for each women's thigh were: array of 2000 infrared LEDs (850 nm) with an area of 1,110 cm(2), 100 W, 39 mW/cm(2), and 108 J/cm(2) for 45 min. The submaximal constant-speed exercise on the treadmill at intensities between 85% and 90% maximal heart rate (HRmax) with or without phototherapy were performed during 45 min, to perform the thermographic analysis. Thermography images were captured before the exercise (t = 0), after 10, 35, and 45 min of exercising (t = 10, t = 35, and t = 45) and at 5 min post-exercising (t = 50). Results: The LED group showed an increased cutaneous thigh temperature during the exercise (from 33.5 +/- 0.8 degrees C to 34.6 +/- 0.9 degrees C, p = 0.03), whereas the exercise group showed a reduced cutaneous temperature (from 33.5 +/- 0.6 to 32.7 +/- 0.7 degrees C, p = 0.02). The difference between the groups was significant (p < 0.05) at t = 35, t = 45, and t = 50. Conclusions: These data indicate an improved microcirculation, and can explain one possible mechanism of action of phototherapy associated with physical exercises.