Unlocking the Chemistry of Exercise

Unlocking the Chemistry of Exercise: How Metabolites Separate the Physically Fit from Unfit: Scientific American
The virtues of exercise are myriad: better cardiovascular health, decreased risk for diabetes, boosted mood, and even perhaps a leaner physique. But aside from such macro links and knowledge about the heart rates, blood–oxygen levels and hormonal responses related to exercise, scientists have a relatively cursory understanding of the chemical mechanisms at work in the body during and after physical activity.
A new study, published online May 26 in Science Translational Medicine, presents a thorough profile of exercise's impact on the human body's metabolites in plasma—and reveals vast biological differences among more- and less-fit individuals.