Exercise training improves our performance, fitness, and overall health. It is not just a powerful tool for prevention but also an effective treatment for many illnesses. There are several connections between metabolism, exercise and skeletal muscle, the key exercise organ. For example, during intense exercise, ATP hydrolysis flux in muscles increases by more than 100 times, triggering a range of acute metabolic adaptations to prevent a drop of the concentration of ATP, which would cause rigor mortis. In response to endurance training, metabolism adapts, such as through mitochondrial biogenesis and this results in a lower blood lactate concentration at a given workload. In contrast, resistance training increases muscle protein synthesis, leading to muscle hypertrophy and this has been demonstrated by stable isotope tracer studies. Global muscle hypertrophy suppresses fat mass and improves glucose homeostasis whereas muscle atrophy has opposite effects. Additionally, metabolites such as lactate, kynurenine or N-lactoyl-phenylalanine (Lac-Phe), play important regulatory roles during exercise. Overall, exercise and muscle metabolism and metabolomes vary from person to person, and, much like in disease, metabolites could serve as biomarkers for exercise-related traits such as fitness and trainability. The mission of the DGM Exercise Metabolism Group is to research all aspects of exercise and muscle metabolism. Our focus is to discover new phenomena of exercise metabolism that are relevant to improving human performance, fitness, and health, and not just confirm or apply existing knowledge.