When we exercise, far-flung parts of our bodies apparently communicate with one another, thanks to tiny, particle-filled balloons that move purposefully through the bloodstream from one cell to another, carrying pressing biochemical messages, according to an important new study of the biology of exercise.

The study helps to clarify some of the body-wide health effects of working out and also underscores just how physiologically complex exercise is.

For some time, scientists have suspected that the body’s internal organs are as gossipy and socially entangled as any 8th-grade classroom. It is thought that, under the right conditions, fat cells chat with muscle cells, and muscle cells whisper to brain cells and everybody seems to want to be buddies with the liver.

These interactions are especially abundant during exercise, when continued movement demands intricate coordination of many different systems within the body, including those that create cellular energy.