How do our muscles respond at the molecular level to exercise? Researchers at Helmholtz Munich and the German Institute of Human Nutrition Potsdam-Rehbrücke (DIfE) have unraveled the cellular basis and signaling pathways responsible for the positive impact of physical activity on our overall health. Regulatory T cells, a type of immune cell, play a critical role in ensuring proper muscle function. These novel insights are paving the path towards precision medicines targeting metabolic disorders like obesity and diabetes, as well as muscle-related illnesses. Their discoveries are published in Cell Metabolism.