Are all resting positions the same? An article published this month from Kent State University explores how the human body rests, and how its evolution from hunter-gatherers to modern office workers can explain the mechanics behind why sitting in chairs can be detrimental to health and metabolism.
The researchers observed the human body in states of inactivity in a modern hunter-gatherer population. The Hazda, a tribe in Tanzania, spent time in a nonambulatory position equal to the time industrial populations spend sitting. However, they do not sit in chairs, and generally do not have the metabolic consequences associated with sedentary lifestyles that populations of the industrialized world face. What’s different about the way they spend their nonambulatory time?
For this study, the researchers used accelerometers worn on the Hazda’s thighs to measure inactivity levels. The team also used electromygraphic data and observational data to reach their results: the Hazda spend 7.54-9.9 hours in a state of inactivity each day. This figure seems a little high because the perception is that hunter-gatherers and other indigenous populations of the world are busy all the time, just making their ends meet to survive. However, it’s how they spend the nonambulatory time that makes a difference to their health.
The difference between the modern office worker/tv watcher and the Hazda is that their inactive time is spent in positions like squatting (due to no chairs or couches). When squatting, the muscles in the lower limb are more activated than when sitting in a chair. Sitting in a chair is associated with lower levels of muscle activity and muscle contractions, resulting in lower muscle metabolism.
The authors of the study believe that the health of the human body is optimized when, even during periods of rest, the body is not completely resting. They feel that the body was adapted to more consistent muscle engagement in its evolution, and the lack of consistent muscle engagement when resting is detracting from our modern muscle health.
We can get the benefits of active rest positions by squatting or sitting less; or in our modern world, sitting on a medicine or yoga ball, etc. The human body wasn’t designed to sit in a sedentary position for extended periods of time. However, this study makes it clear that it isn’t that resting itself is fundamentally bad (the human body, mind, and spirit has to have periods of rest in order to function).
Rather, it’s about how we choose to position ourselves during these resting periods. Hopefully, this can relieve some of the guilt that the modern world experiences over not feeling productive or busy all the time—and that resting is an important part of being human. We just have to be mindful of how we do it.
Raichlen, David A., et al. “Sitting, Squatting, and the Evolutionary Biology of Human Inactivity.” Proceedings of the National Academy of Sciences of the United States of America, https://doi.org/10.1073/pnas.1911868117.