News & Views from the Editor-in-Chief - L. Bruce Gladden
This month's issue contains a special section devoted to summary reviews of the 2018 Physical Activity Guidelines Advisory Committee, and I am calling out three of those papers. First, William Kraus and colleagues noted that daily step counts are a readily accessible means by which to monitor and set physical activity goals. Step counts are a basic unit of locomotion; are an easily understood metric of ambulation; motivate diverse samples of individuals to increase physical activity levels; provide a readily attainable self-assessment of steps through objective, readily obtainable technology; and include a range of activity intensities spanning low- to high-intensity ambulatory exercise. A summary of incomplete evidence shows an inverse dose-response relationship of daily step counts with important health outcomes, including all-cause mortality, cardiovascular events, and type 2 diabetes. The current data suggest a range of 7,000 to 9,000 steps per day are equivalent to, and have similar effects on important clinical outcomes as do the guidelines of 150 to 300 minutes per week of moderate to vigorous physical activity!
In the second highlighted paper, Katzmarzyk et al. summarized the evidence for associations between sedentary behavior and several health outcomes. While the primary focus of previous public health guidelines has been on the benefits of obtaining sufficient levels of moderate-to-vigorous physical activity, there is emerging evidence of hazardous health effects associated with excessive sedentary behavior. A central message of the paper is that people should limit their sedentary behavior, especially if they are not meeting the current guidelines for moderate-to-vigorous physical activity. Alternatively, high levels of physical activity appear to greatly attenuate the risks associated with excessive sedentary behavior. The integration of information on sedentary behavior into the physical activity guidelines is a major advance, one that acknowledges the important interactions between physical activity and other behaviors on health.
Finally Virginia Kraus and coauthors report that there is strong evidence that physical activity decreases pain and improves physical function and moderate evidence that physical activity improves quality of life among people with hip or knee osteoarthritis. These benefits can be obtained from various modes of physical activity (land, pool, aerobic, resistance, flexibility). Even 45 minutes a week of moderate-intensity physical activity can improve or help maintain physical function. Additionally, greater amounts of physical activity—up to 10,000 steps a day—do not appear to accelerate the progression of osteoarthritis. People with lower extremity osteoarthritis should engage in physical activity throughout the day to the extent they are able and be confident in gaining health and arthritis-related benefits.
L. Bruce Gladden
School of Kinesiology