It is undeniable that some cancer patients are not suitable for exercise, but most past clinical studies have concluded that exercise enhances patients’ aerobic fitness – that is, improves cardiorespiratory fitness – and also strengthens patients’ muscle health – and many cancer patients have muscle fatigue and muscle weakness. It can also reduce patients’ anxiety psychologically, helping to regulate their psychology and stabilize their endocrine environment. Overall, the same benefits that exercise brings to healthy people can essentially be brought to cancer patients. Of course, you may say that these are all natural benefits, why do you need to tell us? Well, let’s introduce a new discovery today – exercise can directly shrink tumors! Even Nature has reported this result in Cell in recent days. The study was conducted by a team from Denmark, Sweden, Germany and the United States. In a randomized controlled experiment, this group of experimenters designed different study models for liver cancer, melanoma, and lung cancer, respectively. In the study on melanoma, they had the mice exercise for four weeks ahead of time, then performed subcutaneous implantation of cancer cells, after which they continued to have the mice exercise for two weeks. As a result, the mice that exercised consistently in the hamster ball had a 61 percent lower incidence of skin cancer compared to mice in the control group that did not exercise. And in terms of tumor volume, there was a 67% decrease in adult female mice and a 53% decrease in older female mice compared to the non-exercising control group. Exercise also remained surprisingly effective in terms of lung metastasis from melanoma. After injecting four-week-old male mice with diethylnitrosamine, which is expected to cause liver cancer within 10 months, the researchers found that the incidence of liver cancer was only 31 percent in the mice that exercised consistently, compared to 75 percent in the control group. Also, the mice that persisted in running had significantly smaller liver tumor sizes than the non-exercising controls. In the lung cancer model, mice that exercised consistently had 58% smaller lung tumors and 56% less tumor weight compared to the non-exercising control group. For melanoma, the researchers conducted another experiment in which they observed that exercise delayed the development of malignant lesions in transgenic mice capable of spontaneously developing melanoma. The mice ran roughly 4.1km-6.8km/day. So why exactly? With such an obvious effect of directly targeting tumors, one can’t help but be curious about the principle. First of all, the researchers found that the phenomenon that exercise shrinks tumors is related to the induction of immune-related pathways occurring in vivo. According to the test, the immune system was far more active in the exercising mice than in the non-exercising controls. Next, they noted a key point between the immune system and tumor shrinkage – the frequency of NK cells appearing in the tumors. Although the immune cell activity induced by physical exercise varied in different cancer models and different species of mice, after extensive studies and comparisons, the researchers found that regardless of differences in the regulation of other cells and immune factors, the NK cell response was consistent across models – the frequency with which they appeared in tumors compared to mice that don’t exercise is nothing short of a world of difference. You might say, “Well, isn’t it true that exercise itself makes NK cells appear more frequently? Well, that’s right, and that’s not true. Yes, the researchers observed that in mice without any tumors, the frequency of NK cells increased in the bone marrow, spleen, and peripheral blood if it was exercised as consistently as the experimental group. However, in mice that had developed tumors, insisting on exercise did not result in any increase in the frequency of appearance of NK cells in these sites, but instead, in the tumors, its frequency of appearance was elevated. Does it feel a bit amazing? Through analysis, the researchers concluded that the aggregation of NK cells in tumors is reached through the beta-adrenergic signaling pathway. And they speculate that exercise plays a role in this by providing the general environment that enables this entire pathway to flow smoothly, i.e. exercise allows NK cells to enter the tumor interior to pounce on the tumor cells faster and more efficiently. It is easy to see that exercise has a strong killing power against the multiple tumors in the experiment. And in previous studies, clinical trials for breast cancer and prostate cancer, among others, have also found that exercise improves the prognosis of patients. Of course, exercise must be moderate, and exactly what amount is more suitable for oncology patients still needs to be considered by competent doctors. As for the healthy public, look at the above cancer prevention data – even after being implanted or injected with high-risk carcinogens, malignant tumors can still be avoided through exercise, so let’s move!