Almost 50 years ago Goldstein proposed the hypothesis that muscle cells possess a “humoral” component that contributes to the maintenance of glucose homeostasis during exercise1. Approximately 15 years ago, we identified skeletal muscle as a cytokine-producing organ, demonstrating that the metabolic and physiological effects of exercise may be mediated by muscle derived humoral factors (for review see2,3). The number of myokines discovered by us and others continues to grow, but these have been discovered largely by serendipity. Inspired by the growing appreciation that many of these myokines might be proteins packaged in extracellular vesicles (EV), we have carried out a deep quantitative proteomic analysis of 1159 proteins contained in the EV fraction of plasma in 11 male participants carrying out 1h of cycling. 325 proteins were differentially regulated by exercise with a notable upregulation of several classes of proteins that compose the canonical ~40-100nm exosome. Pathway analysis revealed significant enrichments in a multitude of biological processes and signalling pathways. These data provide a novel mechanism by which newly released exosomes can influence tissue cross-talk and reveal an intriguing pathway by which exercise can exert multiple biological effects and possibly affect disease risk in the setting of obesity.