An analysis of 174 studies found that gardening, household chores and more strenuous activities, when done in sufficient quantities, were strongly associated with a lower risk of stroke and of contracting breast and bowel cancer, diabetes and heart disease. However, the researchers, from the US and Australia, concluded that for the biggest risk reductions, the level of total physical activity per week should be five to seven times the minimum level recommended by the WHO.
At present, the WHO recommends that people conduct at least 600 metabolic equivalent minutes (MET minutes) of physical activity — the equivalent of 150 minutes each week of brisk walking or 75 minutes of running, but the new study suggested most health gains were achieved at 3,000 to 4,000 MET minutes per week. “Major gains occurred at lower levels of activity,” lead author Hmwe Kyu from the University of Washington said. “The decrease in risk was minimal at levels higher than 3,000 to 4,000 MET minutes per week.” “A person can achieve 3,000 MET minutes per week by incorporating different types of physical activity into the daily routine — for example, climbing stairs 10 minutes, vacuuming 15 minutes, gardening 20 minutes, running 20 minutes and walking or cycling for transportation 25 minutes on a daily basis would together achieve about 3,000 MET minutes a week,” Kyu said.
Analyzing studies published from 1980 to this year, the researchers found the pattern highlighted was most prominent for ischemic heart disease and diabetes, and least prominent for breast cancer. For example, people with a total activity level of 600 MET minutes per week had a 2 percent lower risk of diabetes compared with those reporting no physical activity. An increase from 600 to 3,600 MET minutes reduced the risk by an additional 19 percent. The same amount of increase yielded much smaller returns at higher levels of activity.
As the meta-analysis, published in the BMJ on Tuesday, is based on observational research, it cannot draw conclusions about cause and effect, but the authors said their findings have important public policy implications. “With population aging and an increasing number of cardiovascular and diabetes deaths since 1990, greater attention and investments in interventions to promote physical activity in the general public is required,” they wrote. “More studies using the detailed quantification of total physical activity will help to find a more precise estimate for different levels of physical activity.”
In a linked editorial, researchers at the University of Strathclyde and the International Prevention Research Institute in Lyon, France, wrote that the study has importance for the prevention of chronic diseases, but added: “It cannot tell us whether risk reductions would be different with short duration intense physical activity or longer duration light physical activity.” Oliver Monfredi, clinical lecturer in cardiovascular medicine at Manchester University, praised the research, saying: “What is clear, in summary, is that in terms of protecting oneself from the development of these five common and potentially life-limiting illnesses, undertaking any level of exercise is protective, more is better and should be encouraged by healthcare professionals, politicians and charities alike, to decrease the burden of these debilitating illnesses in society today.”
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