The most common system for lower extremity FES exercise is the bicycle ergometer (Glenn and Phelps, 1985). The most common commercially available ergometer is the ERGYS Clinical Rehabilitation System (Therapeutic Technologies, Inc., Tampa, FL). This computer controlled ergometer uses six channels and surface electrodes to sequentially stimulate quadriceps, hamstrings and glutei bilaterally. Some systems also include the capacity for simultaneous voluntary arm crank exercise by paraplegics, thereby permitting hybrid exercise.
Cardiac capacity and muscle oxidative capacity (see Volume II, Chapter 21) have both been shown to improve with FES ergometry. Some subjects can train with FES ergometry up to a similar aerobic metabolic rate (measured by peak VO2) as those achieved in the able-bodied population (Glaser, 1991). Electrical exercise also increases peripheral venous return and fib-rinolysis. There are limits to the cardiovascular benefits of FES ergometry, however, especially in those with lesions above T5. In those patients, there is loss of supraspinal sympathetic control, which in turn limits the body's ability to increase heart rate, stroke volume and cardiac output (Ragnarsson, 1991). Evidence is mixed as to whether FES ergometry can retard or reverse the osteoporosis seen in patients with SCI. In one study of 10 spinal cord injured individuals who underwent 12 months of FES cycling 30 min per day, 3 days per week, bone mineral density of the proximal tibia increased 10%. Unfortunately, after a further 6 months of exercise but at a frequency of only one session per week, the bone mineral density reverted to pre-training levels (Mohr et al., 1997).
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