Aggie Mika, 3rd year graduate student in Integrative Physiology
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| Ancient Greek runners portrayed on a vase. Source: Brittanica.com |
We all know exercise is good for us. Regular exercise can
boost energy and increase physical fitness as well as prevent and treat heart
disease, diabetes and obesity. Moving our bodies can help us combat mental
illness, stave off age-related mental and physical decline, and improve our
ability to think, solve problems, learn, remember, regulate emotions, and cope
with stress. We also now know that sitting around for most of our lives can
lead to poor health. Simply put, scientists studying the biology of exercise
have increasingly shown that we need to exercise in order to be our best,
healthiest, happiest selves. Ever wonder why
nature molded us in this way? Why is every facet of our physiology
seemingly programmed to benefit from exercise? We may be able to shed light on
these questions by studying the evolution of our early human ancestors.
Preceding the 2012 Olympics, Nature published a thought
provoking commentary explaining why exercise evolved to be a vital component of
human health1. The authors describe that over millions of years,
environmental changes required early humans to undergo physical transformations
to promote greater aerobic capacity and endurance so that they could hunt down
food and survive. Dense forests turned into flat, open savannahs and early
human ancestors underwent adaptations that allowed them to evolve from tree
dwellers into runners, physiologically equipped to outlast their prey.
Over time, exercise transformed our minds as well as our
bodies. Our skeletons changed so we could support running, and our bodies grew
more able to take up and use oxygen. Exercise also helped evolve our brain
centers for reasoning, cognition, social behavior and complex emotions, with
the help of exercise-induced increases in brain-derived neurotrophic factor
(BDNF). BDNF is a protein that is released in the brain and body in response to
exercise. Within the brain, BDNF plays a vital role in strengthening
connections between brain cells and promoting their growth and survival. The
release of this protein during exercise helped sculpt brain regions involved in
higher learning and complex behaviors as early humans evolved into a more
intelligent, creative species1.
Flash forward a few millennia. Though the majority of us no
longer have to chase down our dinners, we still need to exercise in order to
live long, healthy lives. The authors of this Nature paper have placed
knowledge concerning the health benefits of exercise into an evolutionary
context, and argue that exercise is an indispensable part of our basic biology.
It’s a bit of a different take on why we should engage in regular exercise: not
only is exercise beneficial, but we as humans are evolutionarily predisposed to
require it for optimal health.
Indeed, scientists attribute our modern, sedentary
lifestyles as a major causal factor for heart disease, stroke and
diabetes--some of our nation’s top killers2. A recent paper even
demonstrated that prolonged periods of inactivity are associated with chronic
disease, cancer and premature death3. Yikes. These results support
the notion that we weren’t meant to spend the majority of our time sitting.
If we were to make exercise a predominant part of our daily
routine, would we live healthier lives, and be free of modern disease burdens? A
large body of research suggests that increasing physical activity can indeed prevent
and significantly improve many diseases of the body and mind. Physically active
individuals are less likely to suffer from joint pain, cardiovascular and
metabolic disease, and even certain cancers2.
Exercise can also have
far reaching effects on the brain, beyond the increases in BDNF discussed in
the Nature piece. The effects of exercise on mental and emotional health are
well documented, and demonstrate that active individuals are less prone to
develop some of the most prevalent mental disorders including anxiety,
depression and age-related cognitive decline4,5. Starting an
exercise program can also improve symptoms for people already diagnosed with
these disorders6,7.
We also may be able
to gain some insight on this topic by looking to the Tarahumara people, a tribe
of Native Americans inhabiting the Sierra Madre Occidental Mountains in
northwestern Mexico. The Tarahumarans are known for their incredible athletic
capabilities, and are some of best distance runners in the world. Exercise is
still very much a part of their daily lives for sport and out of necessity;
running is a means of transportation, hunting and obtaining food, as well as a
welcome pastime. As one might predict, Tarahumarans exhibit exceptional endurance
and cardiorespiratory fitness, low blood pressure, and aren’t plagued by
hypertension, obesity, and high cholesterol8.
So far, science has provided a pretty convincing argument
for why exercise is nature’s most powerful medicine and possibly the cheapest
therapist any of us will ever find. It turns out we may even require it to live
our best lives. Further study of the effects of exercise on health is important
from a basic and applied research standpoint; understanding how exercise
affects our physiology can help us better understand ourselves, while studying
exercise as a form of treatment can help us figure out the causes and
consequences of various diseases.
At CU, there are several exceptional basic
and applied researchers interested in the mechanisms by which exercise affects
our physiology, and how exercise can improve health and prevent disease. This
group of scientists approach these questions from an interdisciplinary
perspective, and are interested in the role of exercise in maintaining physical
fitness as well cardiovascular, metabolic, mental and emotional health. In
future segments, I plan to share with you the data and ideas put forth by this
group of scientists, in hopes to spread word of this energetic science and
perhaps entice you to pick up your running shoes.
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