Most dialysis patients experience prolonged periods of physical inactivity and often bedrest. The physiological consequences of bed rest and inactivity are many and detrimentally affect the functioning of many bodily systems, several of which affect physical functioning. Reductions in plasma volume reduce cardiac filling, stroke volume, and cardiac output. Skeletal muscle fiber size, diameter, and capillarity are reduced, as is bone density. These changes result in profound reductions in physical work capacity. The effects of bed rest and inactivity in patients with chronic renal failure may have more serious consequences, in that they may exacerbate the pathophysiology of renal failure such as cardiac dysfunction, anemia, muscle wasting, muscle weakness, neuropathy, glucose intolerance, and reduced bone density.