Dynamic Thermography: Analysis of Hand Temperature During Exercise

Abstract

Exercise has a noted effect on skin blood flow and temperature. We aimed to characterize the normal skin temperature response to exercise by thermographic imaging. A study was conducted on ten healthy and active subjects (age=25.8+/-0.7 years) who were exposed to graded exercise for determination of maximal oxygen consumption (VO2 max), and subsequently to constant loads corresponding to 50%, 70%, and 90% of VO2 max. The skin temperature response during 20 min of constant load exercise is characterized by an initial descending limb, an ascending limb and a quasi-steady-state period. For 50% VO2 max, the temperature decrease rate was - 0.0075+/-0.001 degrees C/s during a time interval of 390+/-47 s and the temperature increase rate was 0.0055+/-0.0031 degrees C/s during a time interval of 484+/-99 s. The level of load did not influence the temperature decrease and increase rates. In contrast, during graded load exercise, a continuous temperature decrease of -0.0049+/-0.0032 degrees C/s was observed throughout the test. In summary, the thermographic skin response to exercise is characterized by a specific pattern which reflects the dynamic balance between hemodynamic and thermoregulatory processes.

Time required to stabilize thermographic images at rest

“…Studies in the field of thermography have evaluated only the lower limbs [14], hands [8] or whole body [4]. The results of this study suggest different acclimatization times for different body areas.…”

“…One of the main mechanisms is increasing skin circulation, while the systolic volume is decreased. Increased flow of blood to the skin promotes heat exchange mediated by the evaporation of sweat and may increase the T SK to 38°C [8,9]. However, in a neutral thermal environment and at rest, T SK tends to stay in balance, and a significant increase or decrease in its normal levels may indicate a pathological state.…”

“…This lack of consensus [4,8,[14][15][16][17] makes it difficult to determine the optimal acclimatization protocol because each study recommends a different acclimatization period to achieve a stable T SK to ensure the homogeneity of results and allow consistent interpretation and comparison of results between studies. Consequently, the objective of this study was to identify the time required to achieve a stable T SK at rest in a group of young men and women.…”

“…The scientific use of thermography began in medical research, in which it has been used to diagnose vascular disease [11], inflammation [12], tumors [6,13], metabolic disorders and abnormalities in body temperature [12]. In the field of physical activity and sports, some studies have used the technique to study differences in thermogenesis between young and elderly people [14], the effect of exercise on hand temperature [8], and the distribution and variation of T SK during progressive exercise [4].…”

“…Roy and collaborators [16] performed a study in which thermography was used to analyze the time necessary for the temperature in the region of the spine to stabilize and suggested a minimum time of 8 min and maximum of 16 min for reliable measurements [16]. The recommended acclimatization time varies between studies of skin thermometry, with periods of 10 min [14,17], 15 min [8] and 20 min [4] suggested for the subject to remain at rest in a room with controlled temperature and humidity. This variation may be influenced by environmental conditions, especially by the temperature outside the test room.…”