Article

Individuals with walking limitations often experience challenges engaging in
functionally relevant exercise. An adapted elliptical trainer (motor to assist
pedal movement, integrated body weight harness, ramps/stairs, and grab rails) has
been developed to help individuals with physical disabilities and chronic
conditions regain/retain walking capacity and fitness. However, limited published
studies are available to guide therapeutic interventions. This repeated measures
study examined the influence of motor-assisted elliptical training speed on lower
extremity muscle demands at four body weight support (BWS) levels commonly used
therapeutically for walking. Electromyography (EMG) and pedal trajectory data
were recorded as ten individuals without known disability used the motor-assisted
elliptical trainer at three speeds [20,40, 60 revolutions per minute (RPM)]
during each BWS level (0%, 20%, 40%, 60%). Overall, the EMG activity (peak, mean,
duration) in key stabilizer muscles (i.e., gluteus medius, gluteus maximus,
vastus lateralis, medial gastrocnemius and soleus) recorded at 60 RPM exceeded
those at 40 RPM, which were higher than values at 20 RPM in all but three
situations (gluteus medius mean at 0% BWS, vastus lateralis mean at 20% BWS,
soleus duration at 40% BWS); however, these differences did not always achieve
statistical significance. Slower motor-assisted speeds can be used to accommodate
weakness of gluteus medius, gluteus maximus, vastus lateralis, medial
gastrocnemius and soleus. As strength improves, training at faster motor-assisted
speeds may provide a means to progressively challenge key lower extremity
stabilizers.
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