Encouraging sedentary adults to move just a little more every day could produce more widespread population health benefits than urging everyone to meet the current guideline of 150 minutes or more of moderate activity each week, say the authors of two new analyses.
Although the 150-minute goal is still ideal, the authors say, it may be a barrier to the most sedentary and to some older people.
In fact, it may take far less than 150 minutes to achieve a significant reduction in mortality risk in sedentary people, they write in two articles published January 21 in the BMJ.
"Guidelines may be discouraging for fully sedentary people, who have reported feeling 'being pushed too hard,' especially as they get older," writes Philipe de Souto Barreto, PhD, a researcher at Gerontopole of Toulouse, University Hospital of Toulouse, France, in the first article.
Writing in a separate analysis focused on older adults, Phillip B. Sparling, EdD, professor, School of Applied Physiology, Georgia Institute of Technology, Atlanta, and colleagues comment: "We argue that when advising patients on exercise doctors should encourage people to increase their level of activity by small amounts rather than focus on the recommended levels."
The sedentary population has been the least responsive to calls for increased physical activity during the last 2 decades, data show. Across the US population, the percentage of people engaging in no physical activity has remained stable, at 25%, between 1996 and 2014, Dr Barreto reports. In contrast, people who were active became more active, with the number of people who participate in sufficient physical activity rising from 22% in 1996 to 51.6% in 2014.
A mounting body of research shows that too much sitting is associated with increased all-cause mortality, as well as higher mortality from cardiovascular disease and cancer. Sitting is also associated with a higher incidence of heart disease, cancer, and type 2 diabetes.
Dr Sparling and colleagues analyzed accelerometer data from 7000 adults, aged 20 to 79 years, in the US National Health and Nutrition Examination Survey. Those data show low levels of moderate and vigorous physical activity in all age groups, with only the youngest adults, ages 20 to 29 years, reaching the recommended 30 minutes of exercise daily. At the same time, the study found that all adults sat longer than 7 hours a day, the amount identified in earlier research as being associated with increased mortality. The youngest people (aged 20 to 29 years) sat 7.7 hours daily, and the oldest group (70 to 79 years) sat 9.6 hours daily. A study in the United Kingdom found similar results.
"Collectively, these accelerometer findings from the US and UK indicate that, even when exercise intensity is adjusted for age related decline in physical capacity, only some 10-15% of free living, older adults are meeting the minimum standard for 'sufficient activity' (>150 min/week of moderate intensity activity)."
Several studies have shown the benefits of any increase in exercise, the authors of both analyses report. In seven large longitudinal, observational studies Dr Barreto examined, researchers showed that the greatest differences in mortality risk were between the most sedentary and the slightly more active, "suggesting that sedentary people can greatly reduce their risk of all cause mortality with relatively minor increments in physical activity," Dr Barreto writes. All but one of the seven studies showed that people judged "somewhat active" were at a lower mortality risk compared with inactive people, with risk reductions for the "somewhat active" group ranging from 14% to 37% across the studies.
In a study conducted in Norway among 56,072 people, those who engaged in a single weekly exercise session had lower cardiovascular mortality than inactive people, Dr Barreto reports, leading to a relative risk in men of 0.71 (95% confidence interval, 0.59 - 0.86) compared with inactive men. In women, the single session dropped the relative risk even more dramatically, to 0.56 (95% confidence interval, 0.44 - 0.71).
"Small incremental increases in physical activity should be promoted in a slowly progressive manner to maximise health benefits and minimise potential adverse effects," Dr Barreto writes.
Dr Sparling advises that exercise recommendations focus on introducing light activity throughout the day, increasing light activities by 30 minutes daily, and reducing prolonged sitting by suggesting standing or strolling 1 or 2 minutes every hour. People could be advised to get up from their chair during commercials, pace during telephone conversations, and take 5-minute walks three times a day.
"We are not proposing that the 150 minute a week standard be abandoned," Dr Sparling and colleagues write. "Rather, our purpose is to remind colleagues that a broad perspective to counselling is already embedded in the guidelines and that a whole day approach for older sedentary patients may help them move towards the recommended activity levels."
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