Low-frequency electrically induced exercise after spinal cord injury: Physiologic challenge to skeletal muscle and feasibility for long-term use

Skeletal muscle has traditionally been considered a "force generator": necessary for purposes of locomotion, but expendable for non-ambulators who use wheelchairs, such as people with a spinal cord injury (SCI). Active skeletal muscle plays an indispensable role in regulating systemic metabolic functions, even in people with paralysis, but because of severe osteoporosis, high tetanic muscle forces induced with high frequency electrical stimulation may be risky for some individuals. The purpose of this study was to compare the physiologic muscle properties incurred by two low force/low frequency repetitive stimulation protocols (1 and 3 Hz); and, to assess the acceptability of each protocol among people with SCI.