Comparative and evolutionary perspectives on the integrative biology of exercise

Understanding how animals achieve movement and athletic performance in varied conditions requires integration across physiological systems and structural scales from molecules to ecosystems. This special issue on The Integrative Biology of Exercise presents a comparative and integrative perspective rooted in fundamental principles of musculoskeletal biomechanics and energy metabolism, highlighting the methodological advances required to study these principles in a comparative and ecologically relevant context. The special issue adopts a broad definition of 'exercise' that includes any muscle-driven movement that increases energy expenditure above resting levels and elicits acute, plastic and adaptive responses on various time scales. We highlight several themes from the special issue that represent impactful emerging research directions: (1) bridging between human exercise sciences, comparative physiology and movement ecology; (2) exercise capacity, costs, plasticity and adaptation; (3) new technology enabling advances in field-based and minimally invasive experimental measurements in exercise physiology; (4) diversity and adaptation in fuel use for exercise performance; and (5) environmental factors that influence exercise capacity. In line with Journal of Experimental Biology's aims and scope, we focus on combining rigorous, comparative experimental approaches with theoretical and conceptual frameworks to reveal the mechanisms that determine exercise capacity, enable plasticity across lifespan and shape their evolution.