Research on Monitoring Exercise-Induced Fatigue Through Infrared Thermal Imaging and Surface Electromyography: A...

Objectives: This study aims to investigate the correlations between changes in skin temperature and surface electromyography (sEMG) parameters during fatigue induced by varying exercise intensities. The study uses infrared thermal imaging and sEMG to explore whether skin temperature fluctuations can indicate muscle fatigue states. Methods: Two static contraction fatigue tests were administered on the right biceps brachii muscle group of 30 healthy male subjects at 30% and 70% MVC (Maximum Voluntary Contraction) intensity levels. Tests were separated by a 5-day interval and continued until complete fatigue was achieved. The left arm served as a control and was not subjected to any load. Infrared thermal imaging was employed to record continuous skin temperature, capturing data from 120 s pre-exercise to 480 s post-exercise commencement at ten frames per second. Concurrently, sEMG parameters (RMS-Root Mean Square, MPF-Mean Power Frequency, and MF-Median Frequency) were synchronously collected at a sampling frequency of 1 kHz. Results: During 70% MVC exercise, skin temperature on the exercised arm consistently decreased, reaching its nadir by the end of the exercise, with a statistically significant divergence from the baseline (p < 0.05). At 30% MVC, skin temperature initially slightly declined before gradually increasing. The control arm's temperature significantly declined across exercise intensities and during recovery. A significant temporal correlation was observed between skin temperature and sEMG parameters. Conclusions: 1. Variability in skin temperature patterns during muscular fatigue is contingent on the level of exercise intensity. 2. The strong correlation between skin temperature and sEMG parameters suggests that infrared thermal imaging is a promising, rapid technique for monitoring exercise-induced muscle fatigue.