Health benefits of physical activity: the evidence

Abstract

The primary purpose of this narrative review was to evaluate the current literature and to provide further insight into the role physical inactivity plays in the development of chronic disease and premature death. We confirm that there is irrefutable evidence of the effectiveness of regular physical activity in the primary and secondary prevention of several chronic diseases (e.g., cardiovascular disease, diabetes, cancer, hypertension, obesity, depression and osteoporosis) and premature death. We also reveal that the current Health Canada physical activity guidelines are sufficient to elicit health benefits, especially in previously sedentary people. There appears to be a linear relation between physical activity and health status, such that a further increase in physical activity and fitness will lead to additional improvements in health status.

Fig. 1: Relative risks of death from any cause among participants with various risk factors (e.g., history of hypertension, chronic obstructive pulmonary disease [COPD], diabetes, smoking, elevated body mass index [BMI ≥ 30] and high total cholesterol level [TC ≥ 5.70 mmol/L) who achieved an exercise capacity of less than 5 METs (metabolic equivalents) or 5–8 METs, as compared with participants whose exercise capacity was more than 8 METs. Error bars represent 95% confidence intervals. Adapted, with permission, from Myers et al (N Engl J Med 2002;346:793-801). Copyright © 2002 Massachusetts Medical Society. All rights reserved.

Fig. 2: Relation between changes in physical fitness and changes in mortality over time. Participants were evaluated at baseline (PF1) and again 13 years later (PF2). The ratio of PF2/PF1 × 100 was calculated to evaluate changes in physical fitness over the study period compared with fitness level at baseline. For this figure, participants were grouped according to fitness quartiles (Q1 = least fit, Q4 = most fit) for the baseline evaluation and to quartiles for change in fitness from baseline to 13-year follow-up (Q1 PF2/PF1 = least change, Q4 PF2/PF1 = most change). Adapted, with permission, from Erikssen et al (Lancet 1998;352:759-62).

Fig. 3: Theoretical relation between musculoskeletal fitness and independent living across a person's lifespan. As a person ages, his or her musculoskeletal fitness (i.e., muscular strength, muscular endurance, muscular power or flexibility) declines, such that a small impairment may result in disability. Many elderly people currently live near or below the functional threshold for dependence. High levels of (or improvements in) musculoskeletal fitness will enhance the capacity to meet the demands of everyday life and allow a person to maintain functional independence for a greater period.,