Exercise, Twins, & the Brain


A recent study in Finland (Rottensteiner, M. et. al., 2014) examined ten pairs of male twins in their twenties who for the past three years had discordance in their physical activity habits. The sets of twins throughout their lives had shared similar levels of physical activity – for example, they played the same sports or went to the gym the same amount. However, mostly because of work or family related commitments one of the twins activity level began to decline. Not only did the researchers find that the active twin had higher cardiorespiratory fitness, lower body fat percentage, and lower insulin resistance but they also found significant brain differences.

MRI scans revealed differences in the nondominant striatum and prefrontal cortex. More specifically, the putamen in the nondominant hemisphere was larger in the active twins compared to their inactive co-twin. This is an interesting finding because previous research has found these areas are associated with physical activity. In addition, the nondominant prefrontal cortex (including the subgyral and inferior frontal gyrus) was larger in active twins. Overall, long-term physical activity has structural effects on adult brains, especially in areas involved with motor control and coordination. The study suggests that even after a short period, twins who no longer share the same amount of exercise can quickly develop differing bodies and brains.

Work Cited:

Reynolds, Gretchen. “One Twin Exercises, the Other Doesn’t.” Well. The New York Times, 04 Mar. 2015. Web. 11 Mar. 2015. <http://well.blogs.nytimes.com/2015/03/04/one-twin-exercises-the-other-doesnt/&gt;.

Rottensteiner, M. et. al., (2014). Physical activity, fitness, glucose homeostasis, and brain morphology in twins. Medicine & Science in Sports & Exercise, 47, 509-518

Image: http://authoritynutrition.com/wp-content/uploads/2014/10/fat-vs-thin-man-facebook.jpg

5 thoughts on “Exercise, Twins, & the Brain

  1. The study presented in this blog does reveal interesting information about the neurological differences of individuals who exercise regularly and those who exercise rarely. However, what I question about this study is the external validity. The sample size is extremely small, only concerns males and all individuals were roughly the same age. While this study provides a solid understanding to suggest there are biological alterations to the brain caused by exercise, I wonder how this plays out with females as well as with other age groups. Additionally, I am curious about the reasons one twin began to exercise less… I wonder if the twin who exercised less had a better job requiring more hours and couldn’t find the time to exercise quite as much. On the contrary, maybe the twin who exercised more has only a part time job, or isn’t married, allowing them more time to exercise. Overall, I think this study is extremely interesting and merits additional research on how exercise habits may correlate to brain development and change throughout life.


  2. I think that it is very interesting to discover that exercise habits affect the brain. I wonder if there are specific types of exercise that does so- for example, does running for an hour every day have the same effect as weight training or yoga? I also wonder if this brain change plays directly into the motivation that some people manage to find when it comes to going to the gym or exercising in general. Is there some form of feedback that a person used to exercising gets when they exercise? I think it would be interesting to try to look at different forms of working out and the different, long term brain effects that they can cause. I think that the study has a lot of potential for follow-up research and is very interesting in general.


  3. This is a very interesting article. I think learning about twins is fascinating as studies often show just how much neuroplasticity effects the brain. The first question that came to my mind when I read this, is what qualifies an “active” person versus a nonactive person? It would be interesting to see how varied exercise intensities influence these structures–would more intense exercise promote the growth of the putamen?


  4. I agree with the two above posts. I wonder how these findings would present in females. Also, it would be interesting to see the differences across different types of athletic activities. As a college athlete, I wonder if being a player for different sports teams could change the results of this study. Also, I would be interested to see how injury to an athlete would affect the brain differences. The information presented is very interesting but I would really like to see how it would affect more people because the sample size was so small. Differences in the home lives could definitely have been a confounding variable and more people in the study could have helped to neutralize that. There are some really interesting findings here but I definitely think that more research with more participants would be very beneficial.


  5. I find it very interesting that the amount you exercise has such strong effects on the brain. I feel like when you think of exercise most people only see the benefits pertaining to physical fitness/health but not necessarily the health of the brain. Instead of just doing a cross word puzzle or some mind game to exercise the brain you must also take part in actual physical exercise. I think it would be interesting to do more studies and experiments, however, to see how much of a drastic effect on the brain exercise can really have and how beneficial it would be long term.


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