A Study on the Variation in Muscle Fiber Type Composition among Sprinters and Marathon Runners Using sEMG features

Muscle fiber type proportion of skeletal muscles is an important parameter affecting force production, fatigue characteristics, and endurance. Athletic training can change the fiber type proportion. The study intends to generate an inference on the muscle fiber type composition of sprinters and marathon runners by analysis of surface electromyography (sEMG) signals. Signals are recorded from the rectus femoris (RF) muscle of subjects during isometric knee extension protocol with loads until the subjects experience muscle fatigue. Extracted Features include mean frequency (MNF), median frequency (MDF), mean absolute value (MAV), and average energy (AE) are extracted. Results demonstrate spectral compression in the signals of both subject groups. Frequency domain features namely MNF and MDF are found to be higher in the signals of marathon runners during NF and F states when compared to sprinters. However, the time domain features namely MAV and AE are found to be higher in the signals of sprinters indicating the increased concentration of type 2 fibers. The percentage variation (PV) of extracted features is higher in the signals of sprinters compared to marathon runners indicating the greater fatigability of their muscles. Among the different features considered, AE exhibited the highest variation of 54.38 % and 40.19 % in the signals of sprinters and marathon runners respectively during fatigue. Thus, the proposed study reflects the importance of sEMG features in investigating the difference in fiber type composition among sprinters and endurance runners.