Dialysis patients have limited physical functioning as measured by self-reported functioning, peak oxygen consumption, physical performance tests, and tests of muscle strength. A recent study highlighted the severity of debility, reporting that more than one third of hemodialysis patients were unable to perform the normal activities of daily living without assistance. In addition, physical functioning has been shown to be a major determinant of patients' assessment of their global quality of life. Taken together, available evidence suggests that impaired physical functioning is widespread among dialysis patients and profoundly affects their lives. Therefore, interventions to improve functioning in this population have the potential to significantly improve quality of life.