Not everyone will admit this, but there's something magical about exercise. Your brain produces endorphins in response to vigorous exercise and you feel energized, alert, and alive. You derive tremendous satisfaction from doing something you said you'd do. You feel good about yourself all day long. Beyond these benefits related to personal fulfillment, regular vigorous exercise builds strong muscles and bones and strengthens your cardiopulmonary system. Your heart and lungs become substantially more efficient. Your heart pumps more blood with every beat and your lungs take in more air with every breath. Your entire physiology, that is, every one of your cells, tissues, and organs, benefits from a consistent program of regular exercise.

Yet, remarkably, there's more. Medical researchers and public health policy makers have long known that regular vigorous exercise helps improve the health of people with diabetes, heart disease, many types of arthritis, and even cancer. But more recently, within the last couple of years, scientists have been finding that exercise causes lasting changes in the configuration and functioning of human genes.

As we all know, our genetic inheritance is encoded in complex, tightly wound strands of DNA. Our genetic code comprises only four nucleotides - adenine, thymine, guanine, and cytosine - biochemical structures whose precise sequence contains all the information required to produce a living human being. (Some fun facts: There are approximately 3 billion "base pairs" of DNA in a human cell. A single uncoiled strand of DNA is approximately 3 feet (1 meter) in length. In contrast, human cells average 25 millionths of a meter in diameter.). Up until 10 or so years ago, it was generally accepted that genes (specific sequences of base pairs) controlled all protein formation and all physiologic functioning. But within the last 10 years, numerous discoveries have demonstrated a variety of additional factors that contribute to individual genetic expression. One such mechanism involves "epigenetics", the process of "tagging" genes with small "side groups" or "markers". The attachment of a methyl side group (—CH₃), an action known as methylation, modifies a gene's expression, boosting its output or turning it off completely. Researchers have now consistently demonstrated that regular exercise influences and even reprograms the epigenetic pattern of methylation.^1,2

One study has demonstrated that exercise-associated methylation patterns impact genes associated with energy metabolism and insulin response in muscles.³ These findings, if reproduced by follow-up studies, would go far toward clarifying the role of exercise in relieving the symptoms of many chronic diseases.

The conclusion is that not only does exercise make you look good and feel good, it also exerts a profound effect on the most basic components of human physiology. Our long-ago high school gym teachers who exhorted us in seemingly endless rounds of sit-ups, push-ups, pull-ups, and squat thrusts knew what they were doing. It's up to us to continue the program.

¹Denham J, et al: Exercise: putting action into our epigenome. Sports Med 44(2):189-209, 2014
²Ronn T, et al: A six months exercise intervention influences the genome-wide DNA methylation pattern in human adipose tissue. PLoS Genetics 2013 Jun;9(6):e1003572. doi: 10.1371/journal.pgen.1003572
³Lindholm ME, et al: An integrative analysis reveals coordinated reprogramming of the epigenome and the transcriptome in human skeletal muscle after training. Epigenetics 2014 Dec 7:0. [Epub ahead of print]