Exercise physiology is the scientific study of how the human body acutely responds and chronically adapts to physical activity, with professionals in this field utilizing tailored exercise to rehabilitate and manage various health conditions. Its foundational principles were significantly advanced by British physiologist Archibald Hill and German physician Otto Meyerhof, who shared the 1922 Nobel Prize for their pioneering work on muscle energy metabolism, including concepts like maximal oxygen uptake. Today, university-trained Accredited Exercise Physiologists serve as primary healthcare providers, prescribing individualized, evidence-based exercise interventions. A central focus of the discipline is understanding human energy expenditure, revealing how skeletal muscles efficiently convert energy during activity, dramatically increasing metabolic rates compared to rest. This energy is supplied through different metabolic pathways, from rapid anaerobic systems for intense bursts to sustainable aerobic respiration, profoundly influencing the body's overall energy metabolism during sustained physical exertion.