Thermographic response to acute muscle fatigue and delayed onset soreness (DOMS) following a protocol until exhaustion with concentric exercises in the triceps suralis

<i>Objective.</i>Infrared thermography is projected as an innovative and very promising tool for the observation of muscle response to fatigue. The aim of this study was to observe the skin temperature (Tsk) by thermography about acute muscle fatigue and delayed soreness (DOMS) following an exercise protocol until exhaustion in the triceps suralis.<i>Approach.</i>An open longitudinal descriptive observational study of the posterior leg region was performed in 73 healthy subjects. Data on age, sex, body mass index and triceps suralis thermography pre, post and 24 h after maximum muscle fatigue physical exercise, as well as pressure-pain threshold (PPT) and pain sensation by analogic visual scale (VAS) were collected.<i>Main Results.</i>Results showed significant difference in skin temperature over time (Tsk B: 30.1 °C (CI 95% (29.7-30.3), Tsk POST: 29.9 °C (CI 95% (29.6-30.2) and Tsk 24 H: 30.6 °C (CI 95% (30.3-30.9),<i>p</i>= <0.001;<i>η</i>2<i>p</i>= 0.272), side (Tsk right: 30.2 °C (CI 95% (29.4-30.3) and Tsk left: 30.1 °C (CI 95% (29.8-30.4),<i>p</i>= 0.021;<i>η</i>2<i>p</i>= 0.072) and a time x side interaction (Right Tsk B: 30.1 °C (CI 95% (29.8-30.4), Tsk POST: 29.9 °C (CI 95% (29.6-30.2), Tsk 24 H: 30.6 °C (CI 95% (30.3-30.9) and Left Tsk B: 30.0 °C (CI 95% (29.6-30.3), Tsk POST: 29.8 °C (CI 95% (29.5-30.1), Tsk 24 H: 30.6 °C (CI 95% (30.3-30.9),<i>p</i>= 0.011;<i>η</i>2<i>p</i>= 0.061). Regarding the PPT, significant changes were observed over time (B: 9.11 Kg (CI 95% (8.3-10.1), POST: 10.5 Kg (CI 95% (9.7-11.6) and 24 H: 7.64 Kg (CI 95% (7.0-8.3),<i>p</i>= <0.001;<i>η</i>²<i>p</i>= 0.328) and in the interaction between time and sex (men B: 11.0 Kg (CI 95% (9.7-12.3), POST: 12.5 Kg (CI 95% (11.1-13.9), 24 H: 8.8 Kg (CI 95% (7.8-9.7) and women B: 7.4 kg (CI 95% (6.1-8.7), POST: 8.8 Kg (CI 95% (7.4-10.1), 24 H = 6.6 Kg (CI 95% (5.7-7.5),<i>p</i>= 0.050;<i>η</i>²<i>p</i>= 0.041). Finally, the VAS scores showed significant changes over time (B: 0.32 cm (CI 95% (0.18-0.43) and 24 H: 4.46 cm (CI 95% (3.85-5.17),<i>p</i>= <0.001;<i>η</i>²<i>p</i>= 0.831).<i>Significance.</i>According to the results obtained, this technique could be a reliable method to evaluate DOMS. Exploring the integration of thermography with other modalities could provide a global understanding of muscle recovery processes.