Morning physical activity may be the most beneficial against cancer
Disruption of the circadian rhythm due to a mismatch between environmental influences, such as exposure to light or meal times, and our internal 24-hour clock is a possible cause of cancer. It is established that regular physical activity can reduce the risk of cancer and researchers say that this protective effect could be more beneficial if practiced in the morning, with respect to this famous biological clock.
Daily physical activity reduces the risk of developing many chronic diseases, including cancer. It is also a way to limit weight gain, another risk factor for cancer. According to the National Cancer Institute in France, almost 3,000 new cases of cancer per year are due to insufficient physical activity. The body recommends practicing at least the equivalent of 30 minutes a day, with regularity being the most important. Another possible cause of cancer is the alteration of our circadian rhythm or body clock, a 24-hour cycle that regulates almost all biological functions.
Thus, alterations in this rhythm can have consequences both in sleep and in metabolism, the functioning of the cardiovascular system or even the immune system. Most studies on the relationship between circadian rhythm disturbances and cancer risk have focused on night work.
In fact, several of them suggest that factors such as exposure to light at night or late food intake may influence the etiology of cancer. However, researchers still do not know to this day whether the precise timing of physical activity can influence the risk of circadian cancer.
Exercise in the morning for better melatonin production
To answer this question, researchers from the Barcelona Institute of Global Health analyzed the impact of the moment of physical activity on the risk of breast and prostate cancer. They hypothesized that the beneficial effect of regular physical activity in reducing cancer risk may be greatest when the time is right in the morning. This hypothesis was based on the results of a previous study that showed that physical activity practiced in the afternoon and at night can delay the production of melatonin, a hormone produced mainly during the night and with oncostatic properties (it slows the development of known tumors ).
The study published in the International Journal of Cancer included 2,795 participants and the researchers found that the beneficial effect of regular physical activity on the risk of breast and prostate cancer was strongest when it was practiced in the morning, between 8 a.m. and 8 p.m. 10 am In men, the effect was also strong for nighttime activities, from 7 p.m. at 11 p.m. However, the effects were also found to differ between peoples chronotypes, that is, the preference for sleeping and being active at a certain time of day. Thus, morning activity seemed especially protective for late chronotypes, that is, people who prefer to be active at night.
"Improves the protective effect of physical activity"
Researchers have not been able to clearly explain how physical activity can influence the circadian rhythm, but they suggest that certain biological mechanisms may be behind it. For example, a change in the production of melatonin and sex hormones or the way the body metabolizes nutrients. "In general, the results of this study indicate that the time of day to practice physical activity is an important aspect that can enhance the protective effect of physical activity on the risk of cancer", explains in a statement Professor Manolis Kogevinas, coordinator of the study.
This discovery is important because if these results are confirmed, it would improve the recommendations regarding physical activity for cancer prevention.
In any case, "it is clear that everyone can reduce their risk of cancer by doing moderate physical activity for at least 150 minutes a week," the researchers conclude. The internal clock is continuously resynchronized during a 24-hour cycle by external agents, "synchronizers" that act simultaneously. The most powerful of these is light, but physical activity and outside temperature also play a role.