Monday, 15 February 2010

Health benefits of physical activity: the evidence

This is a summary of the main findings from a systematic review carried out by Warburton, Nicol and Bredin (2007. The article can be found here!

Health benefits of physical activity: the evidence
Warburton, Nicol and Bredin (2007)

All cause mortality and cardiovascular disease
Recent investigations have that being physically active leads to reductions in the risk of death from any cause and from cardiovascular disease. For instance, being fit or active was associated with a greater than 50% reduction in risk.
Observational studies have provided compelling evidence that regular physical activity and a high fitness level are associated with a reduced risk of premature death from any cause and from cardiovascular disease in particular among asymptomatic men and women. Furthermore, a dose– response relation appears to exist, such that people who have the highest levels of physical activity and fitness are at lowest risk of premature death.

Several investigators have reported a reduced incidence of type 2 diabetes among high-risk people (e.g., those who are overweight) after lifestyle interventions. Modest weight loss through diet and exercise reduced the incidence of the disease among high-risk people by about 40%–60% over 3–4 years. Exercise interventions for patients with diabetes are beneficial in improving glucose homeostasis. Many studies have shown a strong association between exercise and reduced rates of death from any cause and from diabetes in particular.

Several seminal reviews have been published regarding the relation between cancer and routine physical activity. It appears that routine physical activity, whether as part of a job or as a leisure activity, is associated with reductions in the incidence of specific cancers, in particular colon and breast cancer.

Weight-bearing exercise, especially resistance exercise, appears to have the greatest effects on bone mineral density. There is compelling evidence that routine physical activity, especially weight-bearing and impact exercise, prevents bone loss associated with aging. Exercise training programs were found to prevent or reverse almost 1% of bone loss per year. Exercise training appears to significantly reduce the risk and number of falls.

How does physical activity do this?
Several biological mechanisms may be responsible for the reduction in the risk of chronic disease and premature death associated with routine physical activity. For instance, routine physical activity has been shown to improve body composition, enhance lipid lipoprotein profiles, improve glucose homeostasis and insulin sensitivity, reduce blood pressure and improve coronary blood flow.

Recent studies have shown that exercise training may cause marked reductions in C-reactive protein levels. Each of these factors may explain directly or indirectly the reduced incidence of chronic disease and premature death among people who engage in routine physical activity.

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