Two identical twin brothers in Finland may have helped scientists get a glimpse into the effects of physical activity on not only our bodies, but our brains.
Genetics and our upbringing matter when it comes to exercise and its effects. Genes will affect our endurance, how we respond to different types of exercise, and even whether we enjoy working out at all! The environment of our childhood also influences all of this, making it incredibly difficult for scientists to have test and control groups, since every person has a million different variables. All of this makes identical twins so valuable. By definition, these pairs have the same DNA. If they were raised in the same household, they also had similar upbringing. So they can provide a way to study the effects of changes in lifestyle among people with the same genes and pasts.
Researchers at the University of Jyvaskyla and other institutions in Finland found 10 pairs of identical twins where one exercised regularly and the other did not (often because of lack of time) They then tested to see if these identical people were really identical under their skin.
The scientists measured each subject's endurance, body composition and insulin sensitivity. The scientists also scanned each twin’s brain.
It turned out that these genetically identical twins looked surprisingly different when it comes to physical and mental health. The sedentary twins had lower endurance, higher body fat percentages, and signs of insulin resistance, signaling the future of problems with their metabolism. The twins tended to have very similar diets, whatever their workout routines, so food choices were unlikely to have contributed to health differences.
The twins’ brains also were unalike. The active twins had significantly more grey matter (good!) than the sedentary twins, especially in areas of the brain involved in motor control and coordination.