There is a belief that spending eight hours almost every day without physical activity is uniquely unique to developed and contemporary Western societies. However, as a recent study published in the Proceedings of the National Academy of Sciences points out , it actually seems that it is a habit that already existed in ancient hunter-gatherer societies , and this could put in It questions many of the beliefs we hold about human evolution and about the health problems derived from this inactivity.
And it is that, apparently, the problem could lie not so much in spending that amount of time in rest (physical, at least) but in the way we do it today, in the context of developed countries.
In contradiction to evolution
In fact, the very idea that prolonged rest is bad for our health conflicts with our understanding of evolutionary mechanisms. In particular, and as the authors of the article collect, it has been observed that natural selection tends to favor strategies that require less energy expenditure (which includes rest). And, even so, there is a lot of scientific literature that finds correlations between the time that people spend sitting each day and problems such as excessively high cholesterol levels, cardiovascular diseases or diabetes, sometimes regardless of the physical exercise that is carried out during the rest of the day.
Therefore, this group of researchers decided to investigate the evolutionary context of physical activity in human development.
To this end, they looked to the Hadza tribe of Tanzania, a society that continues to be essentially hunter-gatherer to this day. It is a people that enjoys excellent cardiovascular health (which includes blood pressure, cholesterol levels and the incidence of coronary heart disease) but which, curiously (and although their way of life is very active) seems to pass a high number of hours at rest.
How the Hadza sit
Specifically, the scientists asked a group of Hadza to wear devices for a week that measured the time they were doing some physical activity. And what they discovered is that, on average, they spend no more and no less than ten waking hours a day on rest. A figure that, they point out, is very similar to that observed with similar methodologies in the developed world.
Taking this information into account, they decided to study, instead, the way in which they carry out this rest.
To do this, they observed them for several days, taking extensive notes on what they were doing. And they found that, although they sometimes sit on the floor as well, a good fraction of that resting time (about 20%) is spent in a position much less common in Western societies: squatting.
The advantages of squats
This finding has many important implications . Specifically, because when squatting, the muscles of the legs contract much more often than when sitting.
In turn, these contractions make it easier for the tissues to produce certain enzymes necessary for the processing of fats. Thus, a significantly lower presence of these enzymes could explain the accumulation of cholesterol, with serious effects on cardiovascular health.
In other words, according to the researchers, more than resting time, what could go against our evolutionary physiology is muscular inactivity, since it seems that our body is adapted to a consistent level of muscular activity even during rest. .
According to this idea, changing the chair to squatting during a significant portion of our waking time (in which we are not doing physical activities) could lead to a significant improvement in our cardiovascular health.
Some limitations of the study
It should be noted that, although this research offers a possible explanation for the proven relationship between spending long periods of time sitting and certain harmful effects on our health, it cannot be considered absolute evidence and should be taken with caution.
Particularly because the chain of causality it presents is not empirically verified according to the scientific method, something for which further work in this regard would be necessary.
In addition, there are other important variables that have not been taken into account and that could significantly influence the result. For example, the effects on the body of the intense physical activity that the members of the Hadza tribe engage in on a regular basis have not been separated from those caused by the time they spend at rest, nor has their diet or body composition been studied.
The objective, however, is another. As they affirm, what has been sought here is to gain knowledge about the evolutionary history of the human being. And, in addition, lead us to reconsider the time we spend with hardly any muscle activity. Perhaps, for this reason, it may be a good idea to get into the habit of standing, or even squatting, in those hours that we normally spend sitting.