Combined Application of Electrical Stimulated Antagonist Contraction During Walking (Walking Study)

Electrodes (15 cm x 6 cm) will be placed over the quadriceps and electrodes (11 cm x 6 cm) (Sekisui Plastics Co., Tokyo, Japan) will be placed over the hamstrings. Electrical stimulation parameters will be based on a standard Russian waveform in which a 5,000 Hz carrier frequency is modulated at 40 Hz (2.4 ms on, 22.6 ms off) to deliver a rectangular voltage biphasic pulse. Acceleration sensors as a joint motion sensor (EWTS9PD, Home Appliances Development Center Corporate Engineering Division, Appliances Company Panasonic Corporation 2-3-1-2 Noji-higashi,Kusatsu City, Shiga, Japan) is placed on the front of each leg 88mm above the patellar edge. It analyzes the algorithm of each exercise pattern, and stimulates the antagonist of the motion of each bilateral knee joint during exercise. Electrical stimulation intensity will be set to \~50-60% of 1RM based on the subject's tolerance. The subject's tolerance gradually increases, and electrical stimulation intensity is reset every 2 weeks.

The electrical stimulation intensity will be set under the muscle contraction threshold (but at a level at which the subject can perceive as sensory TENS). Electrical stimulation parameters (i.e. waveform and pulse duration) will be the same of HTS, while the amplitude will be lower. The subject will be stimulated using the same device as for HTS.