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Heat dissipation during sport exercise is an important physiological mechanism that may influence athletic performance. Our aim was to test the hypothesis that differences exist in the dynamics of exercise-associated skin temperature changes between trained and untrained subjects. We investigated thermoregulation of a local muscle area (muscle-tendon unit) involved in a localized steady-load exercise (standing heels raise) using infrared thermography. Seven trained female subjects and seven untrained female controls were studied. Each subject performed standing heels raise exercise for 2 min. Thermal images were recorded prior to exercise (1 min), during exercise (2 min), and after exercise (7 min). The analysis of thermal images provided the skin temperature time course, which was characterized by a set of descriptive parameters. Two-way ANOVA for repeated measures detected a significant interaction (p = 0.03) between group and time, thus indicating that athletic subjects increased their skin temperature differently with respect to untrained subjects. This was confirmed by comparing the parameters describing the speed of rise of skin temperature. It was found that trained subjects responded to exercise more quickly than untrained controls (p < 0.05). In conclusion, physical training improves the ability to rapidly elevate skin temperature in response to a localized exercise in female subjects.

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Among the main physiological stress indicators, the temperature evaluation is very important and innovative because it may be monitored without directly interacting with the animal. The use of a thermographic system, which is based on the detection of infrared radiation emitted by a subject, is a suitable method in order to measure temperature without any contact. In this research, a thermographic system was employed in order to single out the rabbit skin's zones most suitable for the temperature monitoring during stress challenges. Six hybrid rabbits were observed during induced stress; the areas selected as reference were: the ocular area (globe and periocular area), the internal auricle pavilion, and a shaved area of the head. The results of this pilot study show that the thermographic technique is a suitable method for the evaluation of temperature on rabbit. The best areas singled out were the eye bulb, the periocular area and the ear skin. The results concerning the effect of stress on cutaneous temperature showed that during stress condition a decrease in temperature occurs with respect to the basal condition (ΔT~1°C) and this trend is more evident for the auricle pavillion. In fact, this reaction is more evidenced in the ear skin, where a vasoconstriction process occurs. Moreover, corticosterone levels slightly increase (P=0.08) following the stressor's challenge due to tonic immobility test. In this research, both temperature and the change in corticosterone level show that the stress reaction induced by tonic immobility test is stronger than the one due to the other stressors applied to rabbits.

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Although moderate relationships (|r| ∼ 0.5) were reported between skin temperature and performance-related variables (e.g., kinetic), it remains unclear whether skin temperature asymmetry reflects muscle force imbalance in cycling. Therefore, the aim of this study was to assess whether a relationship exists between kinetic and thermal asymmetry during a fatiguing exercise. Ten elite cyclists were enrolled and tested on a maximal incremental cycling test. Peak crank torques of both legs were obtained at the initial and final workload. Likewise, bilateral skin temperatures were recorded before and after exercise. Asymmetric indexes were also calculated for kinetic (AIK) and skin temperature (AIT) outcomes. The bilateral peak crank torques showed a larger difference at the final compared to the initial workload (p < 0.05) of the incremental exercise. Conversely, the bilateral skin temperature did not show any differences at both initial and final workload (p > 0.05). Additionally, trivial relationships were reported between AIK and AIT (−0.3 < r < 0.2) at the initial and final workload. The obtained results showed that changes in bilateral kinetic values did not reflect concurrent changes in bilateral skin temperatures. This finding emphasizes the difficulty of associating the asymmetry of skin temperature with those of muscle effort in elite cyclists. Lastly, our study also provided further insights on thermal skin responses during exhaustive cycling exercise in very highly-trained athletes.