Virtually everyone would agree that exercise improves health, but the mechanisms by which it actually produces those benefits have been challenging to tease out.
Fitness research has come a long way though, and modern science has made a number of interesting observations that help explain how exercise affects your body to improve your health.
The Epigenetics of Exercise
Far from being “written in stone,” genetic expression can be altered by influences coming from outside the gene. This influence alters the operation of the gene, but does not affect the DNA blueprint itself. This process is known as “epigenetics,” and occurs mainly through methylation. As described in the featured article:
Methylation patterns can be altered by a variety of lifestyle changes, such as diet and exercise. Toxic exposure also tends to affect genetic expression, by altering the types of proteins a particular gene will express.
In this way, your environment, diet, and general lifestyle play a significant role in your state of health and development of disease. When it comes to exercise, previous research has found that exercise can induce changes in the methylation patterns of genes found in your muscle cells.
A study published in the journal in 2012 showed that while the underlying genetic code in the muscle remains unchanged, vigorous exercise—even if brief—causes structural and chemical changes in the DNA molecules within the muscles.
This gene activation is induced by , and this contraction-induced gene activation appears to be part of the chain of events that lead to the genetic reprogramming of muscle for strength—and to the structural and metabolic benefits of exercise.
Several of the genes affected by an acute bout of exercise are genes involved in fat metabolism. Specifically, the study suggests that when you exercise, your body almost immediately experiences genetic activation that increases the production of fat-busting proteins.
Previous studies have also identified and measured a wide variety of biochemical changes that occur during exercise. More than 20 different metabolites are affected, including compounds that help stabilize your blood sugar. All of these biochemical changes create a positive feedback loop, resulting in improved health and physical performance.
How Endurance Training Affects Your Genes
These kinds of findings led to another question: does endurance training (opposed to a brief intense bout of exercise) also affect methylation, and if so, how? A Swedish study published in December 2014 sought to shed light on this question.
As reported in the featured article:
The volunteers performed their one-legged pedal exercise, at a moderate pace, for 45 minutes four times a week for three months. The result? The exercised leg was stronger than the unexercised leg, confirming that exercise led to physical improvement, as you would expect.
Genetic alterations within the cells of the muscles revealed there was more to the story however. More than 5,000 sites on the muscle cells’ genome, biopsied from the exercised leg, had altered methylation patterns. These changes were not found in biopsied cells from the unexercised leg. A majority of the methylation changes that occurred in the exercised leg play a role in:
Endurance Training versus High Intensity Exercise
Quite clearly, exercise—in all its forms—tends to have a positive effect. It has the power to affect your entire body, and your overall state of health. Its beneficial impact on your insulin response (normalizing your glucose and insulin levels by optimizing insulin receptor sensitivity) is among the most important benefits of exercise, as insulin resistance is a factor in most chronic disease. According to lead author Malene Lindholm:
High intensity interval training (HIIT) has been shown to be far more effective at producing positive results however, when compared to endurance training. And while the study above concluded that endurance training indeed induces genetic alterations that promote good health, HIIT is known to do so far more efficiently. Mounting research shows that by focusing on endurance-type exercises, such as jogging on a treadmill, you actually forgo many of the most profound benefits of exercise.
Some of the latest research in high intensity exercise involves myokines—a class of cell-signaling proteins produced by muscle fibers—and how they can combat diseases like metabolic syndrome and cancer. I interviewed Dr. Doug McGuff about this research last year. These myokines—which are cytokines produced in muscle—are very anti-inflammatory. They also increase your insulin sensitivity and your glucose utilization inside the muscle. High intensity strength training, also known as “super-slow strength training,” is likely the most effective in terms of activating myokines.
The reason for this is because it induces a rapid and deep level of muscle fatigue. This triggers the synthesis of more contractile tissue, and all the metabolic components to support it—including more myokines. If you still have not incorporated high intensity exercise into your fitness regimen, I highly recommend getting started. You can learn more about HIIT here, as there are many different programs to choose from. I also review the similarities and differences between super-slow and super-super-slow strength training techniques in this previous article.
The Many Biological Effects of Exercise
Getting back to the effects of exercise in general, a number of biological effects occur when you work out. This includes changes in your:
Exercise Is Important for Optimal Brain Health, Too
Mounting research also shows that exercise is as important for your brain function as it is for the rest of your body. In fact, it may be part and parcel of staying “sharp as a tack” well into old age. For starters, the increased blood flow allows your brain to almost immediately function better. As a result, you tend to feel more focused after a workout. More importantly though, exercising regularly will prompt the growth of new brain cells. In your hippocampus, these new brain cells help boost memory and learning. It also helps both gray and white matter in your brain, which prevents cognitive deterioration that can occur with age
Genetic changes occur here, too. The increased blood flow adapts your brain to turn different genes on or off, and many of these changes help protect against diseases such as Alzheimer’s and Parkinson’s. A number of neurotransmitters are also triggered, such as endorphins, serotonin, dopamine, glutamate, and GABA. Some of these are well-known for their role in mood control. Not surprisingly, exercise is one of the most effective prevention and treatment strategies for depression. Three of the mechanisms by which exercise produces these beneficial changes in your brain are:
In animal research, mice with access to running wheels reduced the BMP in their brains by half in just one week. In addition, they also had a notable increase in another brain protein called Noggin, which acts as a BMP antagonist. So, exercise not only reduces the detrimental effects of BMP, it simultaneously boosts the more beneficial Noggin as well. This complex interplay between BMP and Noggin appears to be yet another powerful factor that helps ensure the proliferation and youthfulness of your neurons.
Exercise Leverages Other Healthy Lifestyle Changes
While diet accounts for about 80 percent of the health benefits you get from a healthy lifestyle, exercise is the ultimate “leveraging agent” that kicks all those benefits up a notch. The earlier you begin and the more consistent you are, the greater your long-term rewards, but it’s never too late to start. Even seniors can improve their physical and mental health—not to mention physical function—by starting up an appropriate exercise program. Strength training is particularly important for the elderly, and super-slow strength training tends to be both safer and more effective than many other alternatives.
I believe that, overall, high-intensity interval training really helps maximize the health benefits of exercise, while simultaneously being the most efficient and therefore requiring the least amount of time. That said, ideally you’ll want to strive for a varied and well-rounded fitness program that incorporates a wide variety of exercises.
I also strongly recommend avoiding sitting as much as possible, and making it a point to walk more every day. A fitness tracker can be very helpful for this. I suggest aiming for 7,000 to 10,000 steps per day, your regular fitness regimen, not in lieu of it. The research is clearly showing that prolonged sitting is an independent risk factor for chronic disease and increases your mortality risk from causes. So standing up more and engaging in non-exercise movement as much as possible is just as important for optimal health as having a regular fitness regimen.