Non-invasive measurement of tibialis anterior muscle temperature during rest, cycling exercise and post-exercise recovery

Abstract

We introduce a non-invasive and accurate method to assess tibialis anterior muscle temperature (Tm) during rest, cycling exercise, and post-exercise recovery using the insulation disk (INDISK) technique. Twenty-six healthy males (23.6 +/- 6.2 years; 24.1 +/- 3.1 body mass index) were randomly allocated into the 'model' (n = 16) and the 'validation' (n = 10) groups. Participants underwent 20 min supine rest, 20 min cycling exercise at 60% of age-predicted maximum heart rate, and 20 min supine post-exercise recovery. In the model group, Tm (34.55 +/- 1.02 degrees C) was greater than INDISK temperature (Tid; 32.44 +/- 1.23 degrees C; p < 0.001) and skin surface temperature (Tsk; 29.84 +/- 1.47 degrees C; p < 0.001) throughout the experimental protocol. The strongest prediction model (R-2 = 0.646) incorporated Tid and the difference between the current Tid temperature and that recorded four minutes before. No mean difference (p > 0.05) and a strong correlation (r = 0.804; p < 0.001) were observed between Tm and predicted Tm (Tm-pred) in the model group. Cross-validation analyses in the validation group demonstrated no mean difference (p > 0.05), a strong correlation (r = 0.644; p < 0.001), narrow 95% limits of agreement (-0.06 +/- 1.51), and low percent coefficient of variation (2.24%) between Tm (34.39 +/- 1.00 degrees C) and Tm-pred (34.45 +/- 0.73 degrees C). We conclude that the novel technique accurately predicts Tm during rest, cycling exercise, and post-exercise recovery, providing a valid and cost-efficient alternative when direct Tm measurement is not feasible.