Prediction of muscle fatigue based on correlation between accelerometer and electromyography signals and muscle mass

Aim: The aim of this study is to estimate muscle fatigue based on the correlation between muscle mass and accelerometer and electromyography signals, which are non-invasive methods. Material and Method: The study included 30 healthy male athletes aged 18–30 years who were involved in amateur/professional soccer (age: 21.53±3.42 years; weight: 72.00±8.70 kg; height: 172.26±19.30 cm; BMI: 26.60±18.33 kg/m²). The athletes were referred to as the "experimental fatigue group." The study was designed using descriptive statistical methods to investigate muscle fatigue based on the correlation between muscle thickness and accelerometer and electromyography (sEMG) signals. Anthropometric measurements (height, weight, age, BMI) were taken; muscle thickness (VLO, VMO, RFO) was assessed by ultrasonography. Isometric contractions were recorded at 90°, 60°, and 30° knee angles using a Cybex device. Participants performed leg extensions for 20 seconds with their dominant leg. sEMG and acceleration signals were collected simultaneously using the Noraxon system, and electrodes were placed on the muscles according to SENIAM criteria. Two accelerometers were used for muscle twitching; one was placed on the thigh (VLO, VMO, RFO), and the other was placed on the tibialis anterior in the leg. Results: A significant difference was found between age and muscle thickness and sEMG (p<0.01, p<0.05). Median frequencies differed between muscles at 90°, 60°, and 30° angles (p<0.01, p<0.05). Significant differences were found between isometric data and BMI, age, muscle thickness, sEMG, height, weight, accelerometer, and maximum voluntary contraction (p<0.01, p<0.05). There was a difference between accelerometer pre-contraction and contraction data and maximum voluntary contraction and isometric force (p<0.01, p<0.05). A significant difference was also determined between maximum voluntary contraction and median frequency (p<0.01, p<0.05). Conclusions: As muscle thickness increased, maximum voluntary contraction, isometric force, and fatigue increased. Median frequency increased between joint angles, indicating increased muscle activation. As maximum contraction and force increased, displacement acceleration decreased. A weak correlation was found between accelerometer readings, sEMG, and muscle thickness; however, these results are not statistically significant. Keywords: Muscle Fatigue, Surface Electromyography, Muscle Vibration, Muscle Thickness, Accelerometer