Double Take

Abandoning a routine fitness regimen can trigger negative changes in both the body and brain.  M. Rottensteiner, from the University of Jyvaskyla (Finland), and colleagues assessed 10 pairs of identical twin men. Each set of twins was in their mid-30s, and each had been brought up in the same household. As identical twins, they shared the same DNA. The only difference was that though they had maintained the same level of physical activity for most of their lives, one twin had markedly reduced his exercising in the past few years; on average, the active twin worked out at least twice a week, while the less active twin exercised less than twice a week. The researchers conducted extensive measurements of body composition, glucose and insulin levels, and brain MRI scans.  The more active twins had lower body fat percentage (20.7 versus 24), better endurance levels, and normal insulin sensitivity; the sedentary twins carried about 7 more pounds of body fat, and had worse endurance and insulin sensitivity that showed signs of early metabolic disease. Perhaps more importantly, the team observed that the athletic twins had more gray matter – particularly in areas that controlled balance and motor function. The study authors submit that: “Among healthy adult male twins in their mid-30s, a greater level of physical activity is associated with improved glucose homeostasis and modulation of striatum and prefrontal cortex gray matter volume, independent of genetic background.”