Evaluating indices of age-related muscle performance by using surface electromyography

Recently, there has been an increasing focus on the rapid reduction of muscles that are required for the bending of the hip joint during walking (flexor muscles around the hip joint) with age. The flexor muscles around the hip joint include femoral rectus and abdominal muscles. These muscles have been implicated in falling in the elderly. In this study, we examined the smoothed surface electromyography (sEMG) of femoral rectus muscles during biofeedback training (BFT) of the dominant leg. To this end, we developed parameters for the measurement of shapes in the smoothed sEMG, and evaluated the changes in these parameters in the muscles with age. Statistical analysis indicated that it was necessary to include the time constant of the exponential decay curve fit to maximal points during prolonged muscular contraction, to evaluate the changes with age by using the smoothed sEMG during BFT. Reduction of the muscular regulation capacity due to aging can be detected by performing sEMG during BFT by using the time constant.