The Metabolic Marvels of Movement over the 24-hour Period

Soren Harnois-Leblanc, PhD

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​Staying active and limiting sedentary time may require a bit more encouragement over these cold winter months. Here is one incentive: did you know that you can optimize your health by considering all movement behaviors and their influence on each other over a 24-hour period?

​The Physical Activity Guidelines for Americans, 2nd edition, provide age group- and condition-specific (such as pregnancy) guidelines for physical activity. For example, children and adolescents should get at least 60 minutes of moderate-to-vigorous physical activity daily, and for adults, it should be at least 150 minutes (or 2.5 hours) weekly. Brisk walking, shoveling, running, and taking an aerobics class are moderate-to-vigorous intensity activities. All age groups should also strive to include bone-strengthening physical activity at least three days a week. The Canadian 24-hour movement guidelines follow similar targets, but emphasize the importance of balancing physical activity with sedentary behaviors and sleep over a 24-hour period, as all three factors are interconnected.
 
That means we should look at our movement behaviors over a 24-hour period. Every little movement counts, such as taking the stairs, walking to work or during lunchtime, or even getting up from your chair at work to go get water or ask a question to a colleague throughout the day. So it may be that on a given day, you did not do your planned workout/preferred activity of the moment, but with the several non-structured activities, it accumulates to the daily 30 minutes that is minimally required by the guidelines, five days a week.
 
What else is different with the 24-hour movement concept? It highlights that the time we allocate to one behavior will affect the other behaviors. This is where it becomes even more motivating because you get a two-for-one benefit by making small changes. For example, by choosing to go on a walk after dinner with your significant other, you probably cut down 20 minutes of social media scrolling on the couch. Or by leaving your phone outside of the bedroom, you reduce screen time by allocating this time towards sleep.
 
Overall, by considering the integration of all three behaviors throughout the day, we realize that taking little actions can have huge benefits. One study in youth showed that even small increments in physical activity, by as little as 10 minutes a day, can improve insulin sensitivity and reduce insulin secretory requirements, potentially preventing prediabetes and type 2 diabetes. The study findings also suggest similar benefits by cutting down screen time by one hour a day. In another study in youth that considered all movement behaviors over 24 hours using compositional data analysis, vigorous physical activity relative to other behaviors was linked to lower waist circumference and higher HDL-cholesterol levels, therefore, in favor of better metabolic health. Lastly, a systematic review and meta-analysis found that adults who interrupted prolonged sitting periods with physical activity showed, on average, a lower rise in glycemia and lower insulin response following meals. Thus, regularly cutting work in a seated position with breaks (i.e., getting a cup of tea in the kitchen, doing some standing stretches), could protect against type 2 diabetes development.
 
Overall, until the nice weather returns, it can be helpful to remember that for your metabolic health, every little bit of physical activity counts – both structured and unstructured. It may be easier to stay active this time of year if you enjoy winter activities, and if not, just remember that small adjustments aimed at increasing physical activity and sleep are also beneficial.
 

Author
​Soren is a postdoctoral fellow in the Division of Chronic Disease Research Across the Lifecourse (CoRAL) in the Department of Population Medicine at Harvard Medical School and Harvard Pilgrim Health Care Institute. Her work supported by the Pyle award and the American Diabetes Association fellowship aims to better characterize the role of diet on diabetes risk markers from early childhood to late adolescence in Project Viva pre-birth cohort using causal inference methods. She additionally investigates how the associations between diet and diabetes risk markers differ based on the children’s sex assigned at birth and genetic predisposition to diabetes. More broadly, her research focuses on the prevention of obesity, type 2 diabetes and cardiovascular disease over the first decades of life. 
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