The types of molecules also ranged widely, with some involved in fueling and metabolism, others in immune response, tissue repair or appetite. And within those categories, molecular levels coursed and changed during the hour. Molecules likely to increase inflammation surged early, then dropped, for instance, replaced by others likely to help reduce inflammation.
“It was like a symphony,” says Michael Snyder, the chair of the genetics department at Stanford University and senior author of the study. “First you have the brass section coming in, then the strings, then all the sections joining in.”
Interestingly, though, different people’s blood followed different orchestrations. Those who showed signs of insulin resistance, a driver of diabetes, for instance, tended to show smaller increases in some of the molecules related to healthy blood sugar control and higher increases in molecules involved in inflammation, suggesting that they were somewhat resistant to the general, beneficial effects of exercise. The levels of other molecules ranged considerably in people, depending on their current aerobic fitness.