Sex-Related Differences in Skin Temperature Responses Induced by Small-Sided Games Assessed Using Infrared Thermography

Introduction: Infrared thermography (IRT) enables non-invasive assessment of exercise-induced changes in skin temperature (Tsk); however, evidence on sex-related responses to soccer-specific exercise remains limited. This study compared Tsk responses and bilateral thermal asymmetry between women and men soccer players following a small-sided game (SSG). Methods: This repeated-measures experimental study included 46 university soccer players (22 women, 24 men), who completed a standardised 4 vs. 4 SSG. Thermographic images were obtained before (Pre), approximately 5 min after exercise (Post), and 10 min after the Post assessment (Post_10). Tsk was assessed in eight lower-limb regions of interest (ROIs). Linear mixed-effects models examined Sex × Time effects, with participant included as a random intercept. Results: Significant Sex × Time interactions were observed across all eight ROIs (Holm-adjusted p < 0.001). Women showed greater increases in Tsk than men from Pre to Post (between-sex differences: 0.86–1.55 °C) and greater net changes from Pre to Post_10 (1.16–1.70 °C). No between-sex differences were observed for the change from Post to Post_10 (all Holm-adjusted p > 0.05). Bilateral thermal asymmetry showed no significant Sex × Time interactions (all p ≥ 0.390). Conclusions: Women and men exhibited different Tsk responses following the SSG, particularly at the Post assessment and in the net change from Pre to Post_10, whereas changes during the 10 min recovery interval were comparable between sexes. Bilateral thermal asymmetry also showed comparable temporal patterns. These findings highlight the importance of considering sex and assessment timing when interpreting exercise-induced Tsk responses using IRT.