To assess how skin temperature could be related with gastrocnemius muscle activation and thus detect association between the extensibility of the triceps-surae and the skin temperature pattern.A Cross Sectional Study. Secondary level of care.Recreational runners from an athletic club.57 healthy male subjects with functional equinus condition were recruited (age 42.82 ± 6.97 years, height 173.68 ± 9.79 cm, weight 73.19 ± 8.13 kg, body mass index 20.41 ± 2.48).Skin temperature and electromyography of the gastrocnemius muscle before and after running exercise.Skin thermal assessment value for Gastrocnemius muscles were assessed in 57 participants before and after running. We found a significant increase of skin temperature after running deeply related with electromyography values (Confidence interval 95%). The temperature of Gastrocnemius was increased in runners after activity.Thermal imaging is deeply related with muscle pattern activation for lower limb. Based on our findings, we propose that infrared thermography assessment of the gastrocnemius is adequate to check Gastrocnemius muscle activity condition in runners.