Today I’m reporting on two studies that show how intense exercise suppresses cancer. In the first trial, I'm summarizing the results from a fabulous study conducted by scientists in Sweden which makes a powerful statement about how the benefits from intense exercise can reduce cancer risk.
The images on the left above show cancer and tumor growth in non-exercising subjects compared to dramatic reduction in tumor incidence and growth in subjects that engaged in intenst exercise.
THE STUDY: Ten men were recruited for this study. The volunteers were instructed to perform 60 minutes of exercise on stationary bicycles at increasing levels of intensity. For the first 20 minutes, the men cycled at 60 rpm, which wast a median (range) work rate equal to approximately 50% of VO2-max. For the remaining 40 minutes, the exercise increased to a high-intensity rate that was equal to about 65% of VO2-max. The full title of this study is: The Effect of Acute Exercise on Prostate Cancer Cell Growth.
Blood samples were taken before exercise began (pre-exercise rest serum) and again 1-hour after completing the exercise (post-exercise serum). The researchers then spun the blood to separate the red blood cells from the actual serum. The pre-exercise and post-exercise blood serum samples were then exposed to an established line of prostate cancer cells.
Cancer cells exposed to the men’s pre-exercise serum continued to grow. However, the serum extracted directly after completion of intense exercise had a profound inhibitory effect on the growth of the cancer cells.
Human Tumor Study: One of the ways commonly used to study human cancers is to inject human cancer cells into mice and monitor the rate of tumor growth. In a second part of this study I am reporting on, researchers exposed (incubated) human prostate cancer cells to both the pre-exercise and the post-exercise blood serum for 48 hours. These human cancer cells were then injected under under the skin of mice.
After 14-days, the mice injected with human prostate cancer cells that had been incubated with the men’s post-exercise serum showed ZERO tumor incidence compared to 20% tumor incidence in the mice injected with cancer cells incubated with the men’s pre-exercise serum. The delay in tumor formation from prostate cancer cells exposed to post-exercise serum persisted throughout the experiment up to 34 days.
SUMMARY: Intense Exercise Inhibits Cancer Cell Growth & Formation of Tumors.
Part 1 of this study showed that exposing human prostate cancer cells to blood serum of men drawn directly after intense exercise inhibited the growth of the cancer cells in a test tube (in vitro) experimental model.
Part 2 of this experiment showed that human prostate cancer cells incubated with men’s blood serum drawn directly after intense exercise inhibited tumor growth in mice (in vivo).
Another exercise-inhibits-cancer study published in the journal Cell Metabolism reported that regular exercise reduces the risk of cancer and disease recurrence. In this study, tumor-bearing mice were randomized to cages with running wheels vs cages with no running wheels. The mice who spent their free time exercising on the running wheels showed over 60% reduction in tumor incidence and 50% reduction in growth across five different tumor models compared to the less active control group that did not have access to running wheels.
The researchers discovered that high-intensity exercise produces a surge of adrenaline that helps move cancer-killing immune (NK) cells toward lung, liver, or skin tumors implanted into the mice. A strain of mice that are genetically depleted of NK cells were used in this study. This allowed the researchers to determine that the exercise-induced increase in the number of NK cells at the site of the tumors in the lungs, liver and skin was responsible for the reduction in the incidence of tumors and reduction in tumor growth.
I hope the results from these studies encourage people to be more committed to engaging in intense exercise on a regular basis (at least 2 to 3 times per week).