Newsletter #160: Physical Activity versus Sedentary Behavior đ€ž
Hello again friends, and welcome to the Memorial Day weekend edition of the humanOS newsletter! đș This week, we looked at some new research examining some of the well-known health benefits of physical movement, the problems associated with sitting, and how these interact with one another.
We learned that people who maintain substantial weight loss are more physically active than obese counterparts, but they also spend much less time sitting throughout the day. We also found out that exercise is linked to reduced risk of dying (duh), but whether and to what extent it does this depends on how much time you spend sitting. Finally, we found out that exercise for leisure and exercise for work are very, very different in terms of health effects.
To find out the details, scroll down đđŒ
Question of the week
đ€Â Ten thousand steps is a popular daily walking target (itâs what I generally shoot for). But where did that specific number originally come from?
đĄAnswer
This Weekâs Research Highlights
đșÂ People who have maintained significant weight loss sit less and move more than people maintaining an obese BMI.
Researchers examined physical activity and sedentary behavior patterns in participants in the Weight Watchers Success Registry (n=4305), an observational study of people who lost at least twenty pounds in the WW program and had maintained it for at least a year, and compared them to a control group of weight-stable individuals with obesity. The researchers found that the group that had maintained weight loss spent on average 3 hours less per day sitting compared to controls. Furthermore, weight loss maintainers expended more than twice as many calories per week in physical activity (1835 versus 785 calories), and expended three times more calories per week in moderate-to-vigorous physical activity (678 versus 182 calories). Across both groups, higher BMI was associated with more time spent sitting. This lines up with prior observational research in long-term weight loss maintainers. Most of the successful maintainers in the National Weight Control Registry are highly active, and consistent physical activity has repeatedly been characterized as one of the best, if not the best, predictors of weight maintenance.
đââïžÂ Regular exercise is beneficial, but how much you move and sit the rest of the time also matters a lot.Â
Researchers combined and analyzed data from six prospective cohorts looking at a total of 130239 people. All of these studies used accelerometers (like Fitbit) to measure how much participants moved and sat throughout the day, and then followed the subjects over a period of 4-14 years to track all-cause mortality. Unsurprisingly, regular daily exercise decreased risk of death substantially. However, when the researchers zoomed in on how much the participants sat on a daily basis, this relationship became a bit more complicated, as the benefits of this exercise seemed to depend on levels of sedentary behavior across the day. For example, 30 minutes daily of exercise was linked to up to 80% reduction in risk of early death for those who spent less than seven hours per day sitting. But for those who spent 11-12 hours per day sitting, the benefit of daily exercise on mortality was abolished. The good news is that the researchers found that longer periods of light activity - like walking or housework - also conferred significant mortality benefits, suggesting that people can adopt different mixtures of activity durations and intensities in order to stay healthy. Of course, intense exercise is far more time efficient: this study found that one minute of moderate to intense exercise was equivalent to six minutes of light activity.
đ·Â A high level of leisure physical activity is linked to health benefits - but occupational activity is not.Â
Researchers examined data on occupational and leisure physical activity from a large cohort in Copenhagen (n=104046), and followed them for a median of ten years. At the end of the follow-up period, the researchers found that moderate, high, and very high leisure activity were associated with 26%, 41%, and 40% reduced risks of death respectively, compared to low leisure time activity.
This pattern was strikingly different, however, when looking at occupational activity. High and very high levels of work activity were associated with 13% and 27% increased risk of mortality. Notably, this was after adjusting for a number of potential confounding variables, including age, sex, lifestyle, health, and socioeconomic factors. This may be due to fundamental differences in how exercise for leisure is performed, compared to the demands of physical labor.
Podcasts We Loved This Week
- Pat Byrne: Inconvenient sleep - why teams win and lose. Via Sleep4Performance.
- Layne Norton: Building muscle, losing fat, and the importance of resistance training. Via The Drive.
Products We Are Enjoying
Fitbit
If you are trying to reduce time spent sitting and increase your daily movement and steps, a physical activity tracker is basically a must. Canât manage what you donât measure, right? Pedometers have actually been around since the 1700s, but modern digital activity trackers obviously offer a lot of other benefits, such as heart rate monitoring, and a much more appealing user interface.
Fitbit remains the most popular brand, and one that we continue to use here (and of course, you can easily sync your Fitbit data to your humanOS Dashboard for a more complete view of your activity patterns over the course of time).
