According to the researchers, vigorous aerobic activity increases the consumption of glucose (sugar) for internal organs, which limits the availability of energy for the tumor.
Tubercle investigations have led to a highly significant finding that may help avoid metastatic malignancy.
How does exercise help protect against it?
Studies have indicated that physical activity decreases the chance of acquiring various forms of cancer by up to 35%. This favorable impact is comparable to the effect of exercise on other illnesses, such as heart disease and diabetes. In this research, we offered a new insight, revealing that high-intensity aerobic exercise, the energy of which is obtained from sugar, may lower the risk of metastatic cancer by up to 72%.
"If the general public's message has been "Be active, be healthy," today we can explain how aerobic exercise may improve the prevention of the most aggressive and metastatic cancers."
The research combined an animal model in which mice were trained under a stringent exercise program, with data from healthy human volunteers who were assessed before and after jogging.
Human data, acquired from an epidemiological research study that observed 3,000 people for over 20 years, found that the risk of metastatic cancer was 72% lower in participants who reported frequent aerobic activity with high intensity, compared to those who did not participate in physical exercise.
The animal model produced a similar outcome, which also allowed the researchers to pinpoint its core mechanism. Taking samples of the internal organs of physically fit animals before and after physical exercise and also after cancer injections, they observed that aerobic activity dramatically prevented the growth of metastatic tumors in the lymph nodes, lungs, and liver.
The researchers anticipated that in both people and model animals, this positive result is connected with the higher rate of exercise-induced glucose intake.
This research is the first to look at the impact of exercise on internal organs where metastases commonly originate, such as the lungs, liver, and lymph nodes.
When studying the cells of these organs, we identified an increase in the number of glucose receptors during high-intensity aerobic activity-increasing glucose uptake and turning organs into efficient energy-consuming machines, much like muscles.
We assume that this occurs because the organs have to compete for sugar resources with the muscles, which are known to burn huge quantities of glucose during physical activity.
Consequently, if cancer develops, the strong fight over glucose decreases the supply of energy that is crucial to metastasis. Moreover, when a person exercises consistently, this situation becomes permanent: the tissues of internal organs transform and become identical to muscle tissue. We all know that sports and physical activity are important for our health.
The research, which analyzed the internal organs, found out that exercise alters the complete body, such that the cancer does not spread and the size of the main tumor also declines.
The findings show that unlike fat-burning exercise, which is generally mild, it is a high-intensity aerobic activity that assists in cancer prevention. If the ideal intensity range for burning fat is 65–70% of the maximal pulse rate, sugar burning demands 80–85%—even if just for short periods.
For example: a one-minute sprint followed by walking, then another sprint. In the past, such intervals were largely characteristic of athletes’ training regimens, but now we also find them in other exercise routines, such as heart and lung rehabilitation.
The results indicate that healthy people should also incorporate high-intensity components into their exercise plans. We expect that future research will allow personalized medicine in the prevention of certain cancers, with doctors evaluating family history to suggest the appropriate form of physical activity.
It must be stressed that physical exercise, with its unique metabolic and physiological effects, demonstrates a better degree of cancer prevention than any drug or medical intervention to date.
Research on the relationship between exercise and cancer
Exercise decreases cancer incidence and recurrence, although the fundamental mechanism behind this association remains largely unclear.
The exercise produces metabolic reprogramming of internal organs that raises food demand and protects against metastatic colonization by restricting nutrient availability to the tumor, establishing an exercise-induced metabolic shield.
Proteomic and ex vivo metabolic capacity investigations of mouse internal organs indicated that exercise stimulates catabolic processes, glucose absorption, mitochondrial activity, and GLUT expression. A proteomic investigation of typically active human plasma indicated enhanced carbohydrate consumption after exercise.
Epidemiological data from a 20-year prospective analysis of a large human cohort of originally cancer-free people found that exercise before cancer onset had a minor influence on cancer incidence in low metastatic stages but considerably lowered the chance of highly metastatic cancer.
In three models of melanoma in mice, exercise prior to malignancy injection strongly protected against metastases in distant organs.
The protective benefits of exercise were dependent on mTOR activity, and blockage of the mTOR pathway with rapamycin therapy ex vivo restored the exercise-induced metabolic shield. Under restricted glucose circumstances, active stroma absorbed much more glucose at the cost of the tumor.
Collectively, these results reveal a collision between the metabolic adaptability of cancer and exercise-induced metabolic reprogramming of the stroma, suggesting a potential to inhibit metastasis by confronting the metabolic demands of the tumor.