Nutritional Pearls: A Little Movement Yields Big Benefits
Your patient is a 42-year-old man in good health. He eats a relatively healthy diet, has no chronic conditions, and maintains a healthy weight. At a recent check-up, he mentions to you that despite knowing he lives a sedentary lifestyle (working at a desk each day and infrequently getting up to move around), he often can’t bring himself to exercise in the evenings. He tells you that because of his otherwise good health, he figures it doesn’t really matter.
How do you advise your patient?
(Answer and discussion on next page)
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Answer: Physical activity does not have to mean time spent in exhausting effort or at a gym.
Recently, an international team of researchers grouped together several studies of people's levels of activity that related those activity levels to the participants' overall risk of death over a designated span of time.
Unlike other research, instead of relying on people to report their own level of activity—notoriously prone to error—the authors utilized only those studies that relied on the most clinically accurate measures of activity available: accelerometers.
After identifying those eligible studies, the authors pursued the further step of requesting the original data from the studies' authors so that all of the data could be analyzed the same way.
Only 6 studies met the rigorous standards for inclusion in this meta-analysis and made their original data available to the authors: these studies utilized either the Actigraph or Actical accelerometer. Both are considered extremely clinically accurate for measurement of movement and are worn on the body in various locations. Indeed, some studies were excluded because the accelerometers were worn on parts of the body that are considered to provide less accurate measurements of overall movement.
The authors utilized a measure of total movement known as CPM (counts per minute), which allowed them to measure physical activity more holistically than using steps or heart rate alone. Thus, they could estimate total volume of physical activity, including time spent doing such mundane activities as gardening or walking through the parking lot or to the bus stop in addition to intentional exercise such as jogging or lifting weights.
The total number of participants in this pooled study was over 36,000 men and women who were followed for at least 3 years and for as many as 14.5 years.
The authors grouped the participants' level of physical activity according to intensity and total amount of time spent at that intensity, and also kept an eye on the amount of sedentary time in each participants' life.
After breaking down the levels of total physical activity into 4 increasing levels and following adjustment for gender, education levels, body mass index, and other variables, the authors found that compared to those in the lowest level of physical activity, those in the second-to-lowest level of physical activity were still 52% less likely to die of any cause. Those in the second-to-highest quartile of physical activity were 66% less like to die of any cause, and those in the highest level were 73% less likely to die of any cause.
Struck by the incredibly large effect that moving from the lowest quartile of physical activity to the second-lowest had on participants' risk of all-cause mortality, the authors reversed their focus and analyzed the risk for 4 increasing levels of sedentary (inactive) time: compared to those who were least inactive, those in the second quartile of inactivity were 28% more likely to die of any cause, while those in the third quartile of inactivity were 71% more likely to die and those most sedentary saw their risk of death from any cause increase more than 260%.
What’s the Take Home?
This research emphasizes the importance of engaging in physical activity for overall health—indeed, by some measures being sedentary is of greater risk to your health than being clinically overweight or even obese. More importantly, however, it shows that "physical activity" does not have to mean time spent in exhausting effort or at a fancy gym (or both). Great suggestions for getting started at increasing your levels of physical activity include parking a little further away than you usually do in the parking lot, getting off one stop before your regular bus stop and walking the rest of the way, and taking the stairs for at least one floor rather than using the elevator for the entire trip.
Ekelund U, Tarp J, Steene-Johannessen J, et al. Dose-response associations between accelerometry measured physical activity and sedentary time and all cause mortality: systematic review and harmonised meta-analysis. BMJ 2019;366:l4570.