Currently, various medical guidelines generally do not distinguish between the two types of physical activity mentioned. It is known that all over the world work is the main source of physical activity for most adults. The first major study of the association of physical labor with the risk of death, heart attacks and strokes, published in the European Heart Journal. It can dampen optimism among those who view exercise-related work as beneficial to health.
Physical Activity Paradox
Physical activity is an effective means of preventing cardiovascular disease and early death. Recent studies have shown that its health effects may depend on where and how a person uses it. A number of high-quality scientific papers demonstrate the benefits of leisure time exercise. But physical activity associated with work is not always associated with improved health.
A large 2020 review found that occupational physical activity is associated with a reduced risk of diabetes, cancer, coronary heart disease, and heart disease. At the same time, it increases the likelihood of developing osteoarthritis, sleep disturbances and early death. However, the authors noted that the available evidence is usually of low quality, so more research is needed on this topic. The weakness of many previous studies was their small size, they could not fully explain the decline in health physical work. For people who work physically, health may also deteriorate for other reasons, including low social status.
The different impact of physical activity during work and in free time has been called the «paradox of physical activity.» Scientists suggest that it can be explained by the different nature of these two types of load. Leisure-time exercise is usually more dynamic, with a degree of severity chosen to improve heart and vascular health. The load at work often requires static stress, it is monotonous, working postures may not change for a long time, rest time is often insufficient.
Physical activity at work does not prolong life and increases health risks
In a new study, scientists analyzed data from more than 100,000 people who participated in a large study of the health of the Danish population in 2003-2014 . All participants filled out questionnaires in which they described their activity in detail.
Compared with those who were not physically active during their free time, those with moderate, high, and very high leisure activities had a 26%, 41%, and 40% lower risk of death, respectively. On the other hand, high and very high physical activity at work was associated with a 13% and 27% increased risk of death, respectively, compared with those who were not physically active.
When studying the risks of heart attacks and strokes, scientists found similar effects. Leisure-time physical activity was associated with a 14-23% reduction in their risk, and at work with a 15-35% increase.
“Many people who do manual labor find that their health improves due to activity at work, so they can completely relax at home. Unfortunately, our data show that this is not the case. These people can still benefit from physical activity in their free time. But the obstacle is that they get tired,” said Professor Andreas Holtermann of the Danish National Research Center for the Working Environment.
Holterman noted that physical work usually does not accelerate the heart rate enough to improve heart health. In addition, heavy lifting for several hours increases blood pressure levels, which is associated with a high risk of cardiovascular disease.
Scientists suggest that the work environment can be organized differently so that work mimics some aspects of exercise and may benefit health. This can be facilitated, for example, by periodically changing the type of activity during the day.