I’m very interested in personalized medicine; in order to personalize it however we need to know how people are different, to put it as simply as possible. When I worked as a personal trainer during my college years, I quickly realized that some people happened to like certain exercises more than others. This observation led me to wonder if my clients’ particular liking of certain exercises was related to that exercise being better for their health. The same concept applies to nutrition as well; we are well-adapted to recognize odors and tastes that could indicate something harmful versus nourishing. So for a while I’ve been thinking that some people do better with low intensity exercise (relaxed hikes, recreational sports for fun, playing outside, walking) and some prefer and respond better to higher intensity exercise (competitive sports, crossfit, rigorous weight-lifting, etc). Ayurvedic doctors suspected the same things, but they recommended that we do the opposite of what we prefer once in a while, to balance ourselves out.
So the study I want to talk about today was the first (generally when researchers submit their protocols they like to emphasize that what they are doing hasn’t been done before, so this study apparently wasn’t done before) to look at individual differences in the change in VO2 max (the maximum amount of oxygen one can use in a given period of time) after exercise training. The subjects (481 of them) trained on a cycle ergometer, or stationary bike, three times a week for 20 weeks.
The results were that some people improved their aerobic capacity a ton, and some almost not at all. And as the researchers knew before already, in twin studies, the variation in the change in VO2 max between groups of twins is much higher than the variation between twins, in response to aerobic exercise training. Here they found the same thing among families. This figure sums up their findings.
What this data shows is that genetic variations explain the varying responses to exercise on oxygen consumption.
Similarly, last week I discussed a paper on rats which found that the low-responders saw a greater inflammatory response to exercise and the high responders showed a higher anti-inflammatory response. If that can be shown in humans, it would completely change the way we think about exercise. I’m sure there are some studies that provide clues to this but I don’t know of them at the moment.
Next week I plan to discuss some of the genes that have been identified after this study that explain the heritability and differences in response to aerobic exercise training. Some of you may be wondering: does this apply to resistance exercise? Considering that a lot of people are into things like crossfit and doing a mix of aerobic and resistance exercise, it’ll be important to come up with a design that can look at that. For now, I don’t know; but I sure think that there is a genetic component, as I kind of mentioned in my introductory paragraph, where I noticed that some people just liked certain exercises more than others and maybe that indicates they would flourish at them. I like sprinting and anaerobic activity so I’m going to do some sprints right now.