A healthy heart and svelte physique are not the only physical changes wrought by exercise: researchers have also identified a host of metabolic changes that occur during exercise in physically fit athletes. These changes, described today in Science Translational Medicine, suggest that exercise revs up the pathways that break down stored sugars, lipids and amino acids, as well as improving blood-sugar control. The results might eventually lead to dietary supplements that boost athletic performance or invigorate patients suffering from debilitating diseases, says study author Robert Gerszten, a clinician scientist at Massachusetts General Hospital in Boston.
Metabolic profiling has lagged behind large-scale studies of gene and protein expression, in part because the collection of metabolites in the human body — sometimes referred to as the metabolome — is so complex. “The alphabet for the DNA world is four letters long, and for the protein world it's twenty amino acids,” says David Wishart, a metabolomics researcher at the University of Alberta in Canada who was not involved with the new work. “The alphabet for metabolites is about 8,000 different compounds, so it's a tough language to learn.” Gerszten and his colleagues assayed 210 of these metabolites to fill a gap in our understanding of the effects of exercise. “It's well known that exercise protects against cardiovascular and metabolic diseases and predicts long-term survival,” says Gerszten. “But how exercise confers its salutary effects is less understood.”