Your Body in an Office Job vs. Your Body in a Physical Job
A British professor named Jeremy Morris began conducting research in the 1940s to test the relationship between physical activity and the risk of heart disease. Since there was no awareness of physical activity at that time, Prof. Morris examined people who did the physical activity as part of their routine work to carry out his research. Morris compared the incidence of heart disease between London's double-decker bus drivers, who spend most of the day in a sitting position, and commuters who are on the move. Later, he also carried out his research on postmen who usually walk a lot during the day. His first studies formed the scientific basis for the field of epidemiological research focusing on heart disease and physical activity.
Awareness of the importance of physical activity has increased, which has led many to think that "anything more is good" when it comes to physical activity. Although the proportion of people who work in physical jobs in the western world is gradually decreasing, the proportion of people who are physically active and perform several training sessions per day continues to increase. This is with the aim of achieving an improvement in physical fitness and health or achieving a younger appearance.
Over the years, morbidity data of people who perform vigorous physical activity as part of their daily work have been published, revealing that the rate of morbidity among this group of people is higher compared to people who perform physical activity, even the slightest, in their free time. This phenomenon was named the "Activity Paradox."
The phrase's meaning is derived from the fact that although both situations involve similar physical effort, lifting weights, which is equivalent to functional training, and walking, which is equivalent to aerobic training, when the activity is performed as part of work over time, it causes an increase in morbidity, while when it is performed in leisure time, it brings the opposite effect.
Over the years, many researchers have tried to understand the root of the phenomenon. Today, several physiological mechanisms are already known, which may be responsible for this. It was found that physical activity at work, as opposed to training, is performed at a lower intensity and for a longer period, detracting from the reduction in the risk factor profile.
Physical activity at work also results in a prolonged increase in heart rate at rest - a risk factor for heart disease. In addition, it is characterised by more static work than physical training, which may cause an increase in blood pressure - another significant risk factor. Environmental factors, such as unsuitable working conditions, such as high temperature or lack of ventilation, are also attributed to the increase in risk factors.
Recently, a study published in the British Journal of Sports Medicine found the main reason for the appearance of the paradox. As part of the study, which was conducted in Denmark, over 5,000 residents were surveyed, and were asked about the degree of activity they perform at work and in their free time. In addition, other factors that may affect the incidence of heart diseases, such as smoking and increased alcohol consumption, were examined.
The study found that the most influential factor is an increase in the level of the inflammatory process in the blood, as measured by the level of CRP proteins, which are secreted during an inflammatory process. The level of concentration of those proteins in the blood is directly related to the level of inflammatory processes in the body, which over time may lead to damage to the inner wall of the blood vessels in the heart and accelerate the sclerotic processes that cause the narrowing of the heart's arteries.
The results of the study show that light physical exertion during work resulted in a 6% increase in CRP levels in the blood, and switching from light physical activity at work to more strenuous activity resulted in a 22% increase.
On the other hand, when it came to physical activity during leisure time, the effect was actually the opposite and resulted in a 27% decrease in CRP protein levels.
The researchers explain the difference in the levels of the inflammatory process in the lack of appropriate recovery and rest time, which leads to an increase in stress levels in the body, which in turn causes an increase in the general inflammatory process. This is compared to physical activity during leisure time which is performed in a limited time, which allows sufficient time for recovery during the day.
The results of the study emphasize the importance of taking time to rest among those engaged in strenuous physical work, but also emphasize the importance of providing recovery time among people who perform many hours of physical activity during the day. Combining rest and sufficient time for recovery is much more important for health than more training or activity.