Effects of physical activity on health status in older adults. II. Intervention studies

This review has focused on a specific part of the relationship of exercise to health. The overall evidence supporting the health benefits of exercise is substantial and has been critically reviewed recently (18, 94). Thus, the United States Preventive Services Task Force recommends that all adults exercise regularly (94). The conclusions summarized below regarding older adults do not affect this basic recommendation. There is solid evidence that exercise can improve measures of fitness in older adults, particularly strength and aerobic capacity. These exercise effects occur in chronically ill adults, as well as in healthy adults. Because physical fitness is a determinant of functional status, it is logical to ask whether exercise can prevent or improve impairments in functional status in older adults. The evidence that exercise improves functional status is promising, but inconclusive. Problems with existing studies include a lack of randomized controlled trials, a lack of evidence that effects of exercise can be sustained over long periods of time, inadequate statistical power, and failure to target physically unfit individuals. Existing studies suggest that exercise may produce improvements in gait and balance. Arthritis patients may experience long-term functional status benefits from exercise, including improved mobility and decreased pain symptoms. Nonrandomized trials suggest exercise promotes bone mineral density and thereby decreases fracture risk. Recent studies have generally concluded that short-term exercise does not improve cognitive function. Yet the limited statistical power of these studies does not preclude what may be a modest, but functionally meaningful, effect of exercise on cognition. Future research, beyond correcting methodologic deficiencies in existing studies, should systematically study how functional status effects of exercise vary with the type, intensity, and duration of exercise. It should address issues in recruiting functionally impaired older adults into exercise studies, issues in promoting long-term adherence to exercise, and whether the currently low rate of exercise-related injuries in supervised classes can be sustained in more cost-effective interventions that require less supervision.