Cardiovascular Exercise, Heredity and your brain
We all know that exercise is good for us. So why isn’t everyone doing it? Are some people just lazy? The answer may not be that simple.
Many studies are illustrating the genetic, hormonal links to exercise and our physical and emotional well being. That’s right, someone may not be ‘just lazy’, but may be genetically programmed to not want to exercise. We’ve always heard that you must exercise to lose weight, but as we’ve discussed in other blog posts, there is a link between hormonal dysfunction and obesity. Now more studies are showing a hormonal (genetic) link for exercise and moods. I’m sensing a trend. Let’s take a look.
In a seven year study of mice divided into groups based on activity levels, the offspring of active parents were more likely to be active than the offspring of sedentary mice. This spanned 43 generations of offspring. Researches also concluded that ‘something’ was going on in the brain of these mice, making them addicted to exercise.1 Mice have similar genes to humans, so could the same thing hold true for us?
In a 2006 human study, researches analyzed exercise participation survey data from the GenomEUtwin project, spread across seven European countries. Researches found 62% of the difference in exercise variation was genetic (hereditary) and not based on social/environmental factors. The genetic factors involved include: differences in dopamine receptors (the feel-good neurotransmitter); the ability to lose weight through exercise; body composition.2
Multiple studies have shown a direct link between exercise and our emotional state. Two studies using the Netherlands Twins registry showed exercisers to be less anxious, less depressed, more extroverted and social seeking. The difference between exercisers and non exercisers was consistent regardless of age, gender, or exercise participation.3 Exercisers also reported higher levels of life satisfaction and well-being. They determined the results are not causal- i.e.- the effects may not be due to the exercise, but rather more likely due to genetics4.
Let’s summarize for a moment- studies are showing that we can be genetically driven to not want to exercise, to be anxious, depressed, and to have an inability to lose weight through exercise. It sounds as if the deck is stacked against some people. It may be, but that doesn’t mean the game is over. There are ways to overcome your genes.
In a classic ‘chicken or the egg’ scenario, you need to exercise to overcome your genetic predisposition to not exercise. Confused yet? Let’s look at how exercise can help overcome our genetics, and then we’ll discuss how to go about it.
Exercise immediately increases dopamine levels. Repeated, consistent exercise can sprout new dopamine receptors, increasing the feel-good effect you would get from exercise. In his new book Spark, The revolutionary new science of exercise and the brain, John J. Ratey also describes the benefits of exercise on Brain Derived Neurotrophic Factor (BDNF). BDNF is a brain protein found in the hippocampus, which helps to build and maintain brain circuitry. BNDF has many key functions including: gene activation in the production of serotonin and more BNDF; improves neuronal function and growth, and protects against cell death. If you do not have enough BNDF, you may not receive the feel good boost from exercise.
Daily exercise works best to improve levels of BNDF. If you exercise on alternate days, your levels will catch up in 2 weeks. Interestingly, if you stop exercising for two weeks, your BNDF levels will drop, but as soon as you restart, the BNDF levels come back quicker than their original improvement. This illustrates a ‘muscle memory’ going on in the brain. You’ve laid down the foundation to grow more BDNF, you just have to ‘Spark’ (catchy title right?) it with new exercise5.
Remember the mice getting ‘addicted’ to exercise? This is how it happens. Exercise is a positive feedback loop in the brain and body that can help overcome your genetics.
The difficulty is getting started and then sticking with a new program. If you walk into a health club in January, it’s packed with new members. By March-April, the gym is back to regulars. Burn out rate is very high when people start an exercise program. When formally sedentary people start an exercise program, they have a tendency to overdo it. If you exercise too intensely at first, you do not receive the benefits discussed above, but will experience negative emotional feelings and fatigue.
Remember, it’s important to get into a new routine slowly, and then switch to an exercise program that is more targeted to your goals.
