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Exercise Shrinks Tumors and Fights Cancer, Research Shows

Craig Leonard March 17, 2016
Exercise Shrinks Tumors and Fights Cancer

One of the things I love about researching fitness and health related materials is that there are new discoveries being made on a daily basis regarding how our bodies benefit from nutrition and exercise.

Reading about these discoveries always gives me a fresh shot of motivation to continue feeding my body well and training it often. Lest I be perceived as a selfish hoarder of motivation, I’d like to share the findings of a new study released last month within the Cell Metabolism publication showing evidence that intense exercise has the power to shrink tumors.

Specifically, the researchers found that the adrenaline surge that follows intense exercise promoted the movement of cancer-killing immune cells (i.e. NK cells) toward tumors within the bodies of mice. The cancer-killing cells didn’t just move toward the tumors, though, they actually honed in on the tumors to attack them and heal the body of their deleterious effects.

The improvement this produced within the tumors was nothing short of amazing.

The mice that engaged in regular, intense exercise on a running wheel experienced a 50% reduction in tumor size.

The combination of NK cells being present in the body and adrenaline being available to mobilize them appears to be the biological pattern responsible for the partial eradication of the tumors.

To understand whether the NK cells were truly behind the tumor size reduction the scientists depleted the NK cells within the bodies of some of the mice. Even with exercise these mice with depleted NK cells still experienced normal rates of cancer growth, indicating that NK cells were indeed responsible for reducing tumors. Without the NK cells present the cancer continued to metastasize without abatement. 

By the way, NK cells are not unique to mice. NK cells are already known to be potent cancer fighters in humans, as well. While the biology of mice and humans certainly differ, NK cells are present in each and appear to function similarly in regard to attacking cancer.

In addition to isolating the NK cells as being an integral factor in the tumor reductions observed, the scientists also were able to isolate adrenaline as being a necessary component. They did this by simply injecting mice with adrenaline to mimic the surge experienced with exercise and observed the NK cells mobilize and home in on the tumors.

While the ability of exercise to prevent and even aid in curing cancer has been understood for quite some time, it’s encouraging to see researchers starting to dig down into the biological functions responsible for it. There’s also the promise that we may even find a way to harness this information to develop a safe and effective cancer treatment option from it in the future.

Another pertinent study found that the cancer-fighting effect of exercise appears to be proportionate with the intensity applied. I’m referring to a study published in the journal, Cancer Epidemiology, Biomarkers & Prevention, which reported that brisk walking cut postmenopausal women’s breast-cancer risk by 14% compared with those who didn’t walk. However, women who exercised with greater intensity were able to reduce their breast-cancer risk by 25%.

This provides yet another reason why high intensity conditioning – like sprinting – is so important to incorporate into your exercise routine. Sprinting increases testosterone and encourages muscle growth. It has also been shown to reduce hypertension, increase the metabolism, and burn fat far better than lower intensity cardio.

As this study alludes, the benefits we’re afforded by regularly exercising our bodies is beyond measure. It holds the power to extend the time we have to make a positive difference on this earth, God willing, and to optimize our quality of life while we’re here. The same can be said for nutrition.

So it’s truly a shame to see so many men and women not taking advantage of all the ways exercise and nutrition can enhance their lives. It’s foolish, really.

Our society throws its collective hands up as if there’s nothing that can be done about the physical impairments and diseases running rampant around us. We can’t eliminate all of them, but we’re certainly not helping ourselves by living sedentary lifestyles and subsisting on calories sources from processed, toxic “foods”.

Science has spoken loud and clear time and time again. If we feed our bodies well and exercise them often the myriad health pandemics wreaking havoc on our society will be drastically mitigated. The choice is ours and, unfortunately, we’ve continued to choose poorly.

Want to learn more about the powerful positive difference nutrition and exercise can make in your life? Check out these Craig Leonard Fitness articles for more on how diet and exercise can improve your health and quality of life:

Eat Plenty of Fruits and Veggies To Cut Your Risk of Death In Half

Just 20 Minutes of “Easy” Exercise Does This…

The Effect Exercise Has On The Brain

Caffeine Enhances Exercise-Induced Testosterone Production

Research Confirms Coconut Oil Increases Testosterone


When It Makes Sense Not to Take Your Medicine

Cell Press. “Running helps mice slow cancer growth.” ScienceDaily. ScienceDaily, 16 February 2016. <>.

Photo Credit – Health Benefits of Basil

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