ABSTRACT
Aerobic dance (AD) is a form of fitness exercise whose program is constructed by a combination of various joint movements. Therefore the exercise is expected to give enough stimulus to not only the cardiorespiratory but also the musculoskeletal system. The purpose of this study was to evaluate the activity level of the leg muscles among the major 22 AD leg movements, or steps (13 low-impact steps and high-impact steps), by electromyography (EMG) analysis. The subjects were two trained AD instructors, who were asked to perform individual steps at a pitch of 144 bpm. EMG data were recorded from the iliopsoas, gluteus maximus, vastus lateralis, biceps femoris, tibialis anterior, and gastrocnemius muscles on the right side by means of surface electrodes. The half-wave of the raw EMG was rectified and integrated over periods of 20 s during the exercise. From the raw EMG data it was observed that the pattern and amplitude of the electrical discharge of each muscle varied in response to the difference in step motion. The integrated EMGs of the iliopsoas, biceps femoris, and gastrocnemius tented to show higher values for high-impact steps in comparison with low-impact steps, but that of the tibialis anterior showed a contrary trend. The mean value and stan-dard deviation of iEMG of each muscle for the 22 steps was calculated for the same subjects, and the muscle activity level was classified into 5 degrees. Making use of this evaluation table, it may be possible to construct an AD program that can activate the leg muscles impartially.