From the first moment my wife discovered she
had breast cancer, there was a deafening silence from the men I know. Even ones
whose wives, mothers or girlfriends had breast cancer seemed to have received a
gag order from some Central Cancer Command and did little more than mumble
about the experience. Not one to shut up for any known reason, I started this blog…That
was four years ago – as time passed, people searching for answers stumbled across
my blog and checked out what I had to say. The following entry first appeared in
May of 2012.
Doctors harp on
exercise.
Despite the harping
– or in my case, perversely because
of it – I avoid exercise like the plague.
Even so, as I read
more and more sites promoting the “exercise makes you better if you have breast
cancer” meme, I found that almost none of them give any kind of evidence as to
WHY exercise fights cancer and promotes healing.
So I dug into the
sites and finally found some evidence supporting this wild, “Do this one weird
thing…” kind of meme. This week, it’s number:
1)
Physical
activity appears to enhance proliferation of lymphocytes, increases the number
of natural killer cells and increases lymphokine-activated killer cells
activity.
What’s a
“lymphocyte”?
What’s a “natural
killer cell”?
What’s
“lymphokine-activated killer cell activity”?
To tell you the
truth, these appear to fade from easily definable to mumbo-jumbo-ish, so let’s
have at it!
But we need to
take one more step backward and start with White Blood Cells.
In contrast to the
RED blood cell, which are the cells that make up the visible part of the blood.
The red blood cells – or rbc’s – are the part of the blood that makes it RED!
It’s red because each of the rbc’s has many heme molecules in it. The heme
molecules are the ones that carry a tiny iron atom in their center. It’s the
iron atom that OXYGEN grabs hold of so that the rbc’s can carry oxygen to the
lungs allowing us to BREATHE. There are zillions of these little suckers in
your bloodstream at all times and THEY come from the marrow in your bones.
So white blood
cells – or wbc’s – don’t have heme in them; therefore they are, by comparison,
WHITE. But they still travel in the bloodstream. Instead of carrying oxygen,
they attack and destroy any germs that get into your body. They also take care
of any other junk that gets in.
Lymphocytes are a
kind of wbc. There are three kinds of lymphocytes – natural killer cells, T
cells and B cells. Another name for the natural killer cells are NK cells. T
cells are the kind of cells that the Human Immunodeficiency Virus (HIV)
targets.
NK cells have the
specific duty of protecting the body from tumors and viruses by “popping” the
cells to destroy them; the other two handle the release of cytokines, lysis and
immune regulation and creating antibodies.
The effect of
exercise on NK cells however, seems to be blasted out of the water by the study
referenced below and quote here: “…latent CMV infection is associated with
lowered numbers of NK-cells expressing inhibitory receptors and a blunted
mobilization of NK-cells in response to acute exercise. This may indicate a
compromised immune response to ‘fight-or-flight’ situations in those infected
with CMV.”
Conversely,
“Moderate exercise has been reported to produce an anti-inflammatory
environment and thus reduce the risk of infection. Conversely, continuous,
intense exercise may increase oxidative stress (an overproduction of reactive
oxygen species compared to the body’s ability to detoxify), inflammatory
responses, as well as the risk for infection.”
And blasting back
from the other side: “Longitudinal training studies in previously sedentary
people have failed to show marked changes in T and B cell functions provided
that blood samples were taken at least 24 h after the last exercise bout.”
Also: “Evidence suggests that the prophylactic effect of exercise may, to some
extent, be ascribed to the anti-inflammatory effect of regular exercise
mediated via a reduction in visceral fat mass and/or by induction of an
anti-inflammatory environment with each bout of exercise (e.g. via increases in
circulating anti-inflammatory cytokines including interleukin (IL)-1 receptor
antagonist and IL-10). To understand the mechanism(s) of the protective,
anti-inflammatory effect of exercise fully, we need to focus on the nature of
exercise that is most efficient at alleviating the effects of chronic
inflammation in disease. The beneficial effects of endurance exercise are well
known; however, the anti-inflammatory role of strength training exercises are
poorly defined. In addition, the independent contribution of an
exercise-induced reduction in visceral fat versus other exercise-induced
anti-inflammatory mechanisms needs to be understood better. There is consensus
that exercise training protects against some types of cancers. Training also
enhances aspects of anti-tumour immunity and reduces inflammatory mediators.
However, the evidence linking immunological and inflammatory mechanisms,
physical activity, and cancer risk reduction remains tentative.”
Translated: “We
don’t know enough yet to say if exercise is magic”.
UPDATE:
February 2016: “In Brief, the beneficial effects of exercise are countless.
Pedersen et al. now link exercise, cancer, and immunity and reveal that
exercise decreases tumor incidence and growth by over 60% across several mouse
tumor models through a direct regulation of NK cell mobilization and
trafficking in an epinephrine- and IL6-dependent manner.”
So it appears
that, four years later, there is strong evidence that exercise isn’t magic, but
science! Dang…now where’s my bike helmet?
