New Findings on Exercise vs Cancer 🏃
This week I would like to revisit a topic that we've touched on a few times here – how physical activity affects cancer, the second leading cause of death in the United States.
Now, a lot of this research has revolved around preventing the onset of cancer, or destroying nascent cancer cells before they can cause trouble.
For example, we know that Olympic athletes live longer than comparable individuals in the general population, and it has been shown that much of the survival advantage enjoyed by elite athletes is explained by reduced mortality from cancer.
But several newly published studies suggest that exercise may also yield tremendous benefits for people who are currently battling cancer, in at least two different ways.
First of all, we know that exercise stimulates the immune system, and enhances the ability of our immune cells to target and kill cancer cells. You might recall we previously discussed how lactate, generated during exercise, appears to rejuvenate T-cells, making them better at fighting cancer.
That's not all though; exercise may also directly affect tumor biology, through factors released by contracting skeletal muscle, independent of cardiorespiratory fitness and other training adaptations.
This Week’s Research Highlights
Researchers in Finland recruited seven patients who had recently been diagnosed with either Hodgkin or non-Hodgkin lymphoma. Prior to the start of their cancer therapy, the subjects visited the laboratory and underwent a 10-minute exercise bout on a stationary bike, performed at a moderate intensity (determined individually for each participant based on prior fitness testing). Blood samples were taken at rest, immediately after the exercise, and 30 minutes after the exercise bout. The blood work revealed that proportions of natural killer cells and cytotoxic T cells both increased in circulation, then returned to baseline at the 30 minute post-workout mark. Notably, greater relative intensity was linked with changes in immune cells: Higher heart rate and blood pressure during exercise was associated with higher levels of immune cells in the bloodstream of these patients. The same research team also performed a very similar trial in newly diagnosed breast cancer patients, with results mirroring that of the lymphoma patients. Right after spending ten minutes on a stationary bicycle, blood samples from these breast cancer patients revealed a 34% increase in CD8+ cytotoxic T cell count, a 130% increase in CD56+CD16+ natural killer cell count, and a 29% increase in total white blood cell count. Now, we've known for some time that exercise leads to an increase in blood levels of immune cells. Immune cells are usually hiding in storage in the spleen and lymph nodes, but physical activity pulls them out into circulation. However, this phenomenon is quite short-lived, as the numbers of these immune cells will drop back down to baseline (or even lower!) in the post-workout window, and that was seen in both of these studies. This may not be a bad thing, though. Research using fluorescent trackers has shown that after immune cells are deployed into the bloodstream during exercise, they don't simply disappear – rather, they are redistributed to tissues that require immune surveillance. In other words, it is entirely possible that exercise not only boosts levels of immune cells in the blood, but also sends them to where they're most needed. Pretty cool huh?
Researchers at Texas A&M University performed a series of experiments to gain insight into the molecular and cellular mechanisms through which physical exercise fights cancer. First, they randomly assigned rats into either exercise or non-exercise groups. The rats assigned to exercise were trained using tiny motorized treadmills with a gradually increasing speed and incline, and the conditioning protocol was designed to resemble current aerobic exercise recommendations for humans. Then, after five weeks, all of the rats were sacrificed, and their hindlimbs were surgically isolated and artificially perfused (basically being kept alive outside of the body in a basin). To mimic the action of exercise, the researchers electrically stimulated these disembodied limbs to force the muscles to contract. The reason for this Frankenstein-esque approach was to totally divorce the muscles from any input coming from other organ systems. That way, the researchers could zero in on factors directly emanating from the muscle and nowhere else. And by comparing the exercise group to their sedentary counterparts, the researchers could examine whether fitness and prior exposure to exercise influenced these compounds. From there, they extracted fluid from the muscles both before and after electrical stimulation, and exposed human breast cancer cells to the media. At the same time, they also examined how these extracts affected cancer in female rodents that had been transplanted with breast tumor cells. Sure enough, they found that this fluid powerfully suppressed growth of the cancer cells, both in the cell culture and in living rodents. In fact, animals with implanted tumors who received the extract from contracting muscle showed almost no tumor growth over the course of the study. Furthermore, it didn't make a difference whether the perfusate was extracted from animals that had trained for five weeks or animals that were totally untrained. The researchers state, "...our results strongly suggest that the mechanistic factors mediating these benefits are normally resident in muscle, and that their manufacture and subsequent release are completely independent of physical conditioning. Perhaps our most exciting finding is that any individual may benefit from repeated muscle contractions, regardless of prior physical conditioning, highlighting the need for physical activity to stimulate the secretion of factors that combat cancer."
Better Brain Fitness with Dr. T
Attempting to acquire new knowledge or cultivate new skills is super humbling. That applies to learning music, foreign languages, sports, and so on. Being a beginner, in any endeavor, means making lots of mistakes. And that is an unavoidable part of the process.
In this episode of the Better Brain Fitness podcast, Drs. Turknett and Wood address how to cope with this uncomfortable aspect of learning.
And this you’d like to submit a question for the guys yourself (and maybe even be featured on the show), hit this link.
Random Trivia & Weird News
Researchers trained 16 pigeons on histopathology in a box with a computer screen, with no humans present (to avoid potential observer-expectancy effects which occur in human-animal interactions). Over the course of a month, their accuracy rate in identifying cancer cells reached an impressive 80%. And when the researchers showed the same images to different pigeons and combined their responses, the accuracy went all the way up to 99% – just as good as a trained human expert.
A pigeon might seem like an unlikely replacement for a professional pathologist, but they actually are surprisingly well-equipped to the challenge. For one thing, they have an exceptional visual system, superior in some ways to that of humans. Furthermore, they are capable of remembering hundreds of images, even for years after initially learning them.
Podcasts We Loved This Week
- Joanne Slavin: How much fiber do we need for good health? Via Sigma Nutrition Radio.
- Pope Moseley: From heat shock doc to kettlebells. Via Inside Exercise.
Products We Are Enjoying
Now, previously we’ve discussed creatine in the context of its ergogenic effects, as well as on the brain. But what about with respect to cancer? Interestingly, scientists were previously concerned that creatine may increase cancer risk by facilitating the formation of carcinogenic heterocyclic amines, but that appears to not be the case. Now there is preliminary evidence to suggest the opposite may be the case. Animals that are supplemented creatine in doses that resemble those taken by human athletes are more resistant to cancer, and genetically engineered mice whose killer T cells are incapable of taking up creatine are more vulnerable to cancer. So creatine is an all-around smart supplement, and the most cost-effective way to take it is through powders. However, if you don’t want to deal with measuring out powders (like if you’re traveling or something like that), these chews are a good alternative that I rely upon regularly.
PS: If you’d like to learn more about how creatine works and some of its myriad benefits, I’d suggest checking out this pod from our good friend Tommy Wood, who I’m pretty sure is creatine’s #1 fan.
humanOS Catalog Feature of the Week
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This week, I’d like to highlight one of the lessons from our course on polarized training, developed by Jeff Rothschild.
Mitochondria are the powerhouses of our cells, as you well know. Accordingly, they also fuel our athletic endeavors, which is why we want to have more of them, and make sure that they are performing at their very best.
In this lesson, Jeff reviews how manipulating training volume and intensity affects the number and function, respectively, of our mitochondria, and how you should plan your training so that you can optimize both of those attributes while still being able to recover.