Did you know that some data suggest physical inactivity increases your risk of dying from any cause more than smoking? Although this argument is still debated, in theory, you could go for a run and have a cigarette and be less likely to die than someone who does neither (you still shouldn’t smoke). Although the jury is still out on whether sitting is truly worse than smoking, in terms of sheer numbers, physical inactivity affects more people’s health.
With the invention of computers, smartphones and transportation to and from work, physical activity has been functionally engineered out of our daily routines. The World Health Organization predicts there will be 500 million new cases of preventable chronic disease related to physical inactivity by 2030 unless something changes rapidly.
This year at the 2023 American Physiological Summit, several researchers gave presentations that focused on the harmful effects of physical inactivity. The session was organized by Frank Booth, PhD, a legend in the field of molecular exercise biology. Booth said it best more than 20 years ago: “Our society is currently at war against the ominous enemy of physical inactivity causing chronic disease,” and the sentiment echoes louder today.
You would think physical activity shouldn’t be that hard to sell, but somehow it still is. If a doctor told you they had a pill that would increase your strength, bone mineral density, mood, cognitive function and nearly every aspect of your health, wouldn’t you take it? Well, that “pill” is regular physical activity. But still, people do not exercise—and the reason may lie within the brain.
Nathan Kerr, a student of Booth’s and a presenter at the Summit, explained how rodents with a high drive to exercise without encouragement have different signaling within the brain in response to exercise and perform better on cognitive tasks compared to rats with a low drive to exercise.
The rats with a lower drive to exercise also had decreased brain plasticity (ability to learn) and increased risk of neurodegenerative diseases. If we can uncover the mechanisms regulating the drive to exercise, that would provide the first step to targeting them with medicine. Could you imagine taking a pill that makes you want to exercise?
The adage you may have heard is true, too: If you don’t use it, you lose it. Data presented at the Summit suggest we might lose it more quickly than we think. Audrey Bergouignan, PhD, showed that five days of total physical inactivity is like a metabolic sledgehammer to the body.
Work published in the Journal of Applied Physiology found that total inactivity causes insulin resistance and altered lipid metabolism—a total reprogramming of cellular processes. Together, this metabolic inflexibility means your body is not adept at switching from one fuel source to another (carbs to fat or vice versa), which can make it difficult to cope with metabolic challenges such as physical activity.
It’s easy for a scientist or doctor to say “go exercise,” but that doesn’t always translate to the real world. Some groups of people, including those who are historically marginalized, have greater barriers to getting regular exercise and are disproportionally less active.
At the Summit, Austin Robinson, PhD, discussed how racial differences in the built environment contribute to the ability to exercise. People who make less money and people of color often have less access to areas designed for exercise, whether that be outdoor green space or gyms. This may also be a major contributor as to why more people in these groups have high blood pressure.
We know that physical inactivity is very bad. By studying the effects of physical inactivity and creating more opportunities and areas where people can exercise, we can start to combat the epidemic of physical inactivity. Until then, be supportive of friends becoming physically active and gently encourage those who haven’t started to do so.
Dain Jacob is a PhD student at the University of Missouri in the Nutrition and Exercise Physiology Department. His research focuses on autonomic regulation of the peripheral vasculature and the impact of environmental stressors and sex hormones. Jacob served as a meeting blogger for the 2023 American Physiology Summit.