exercise physiology

exercise physiology
Name	Exercise physiology
Glossary	Glossary of medicine

exercise physiology is the scientific study of the acute responses and chronic adaptations of the body to physical activity and exercise. It is a sub-discipline of physiology and kinesiology, intersecting with fields like biomechanics and sports medicine. Practitioners, often working in settings like the Cooper Institute or academic departments, apply this knowledge to enhance athletic performance, health, and rehabilitation.

Definition and scope

The field examines how bodily structures, from cellular to systemic levels, function under the stress of exercise. Its scope extends from foundational research in cell biology to applied work in cardiac rehabilitation and spaceflight. Key professional organizations that shape the discipline include the American College of Sports Medicine and the European College of Sport Science. The scope also encompasses studying diverse populations, from elite athletes training at facilities like the Australian Institute of Sport to patients in clinical settings.

Energy systems and metabolism

Muscular work requires immediate energy, primarily supplied by adenosine triphosphate (ATP). The three primary metabolic pathways are the phosphagen, glycolytic, and oxidative systems. The phosphagen system, involving compounds like phosphocreatine, fuels short, high-intensity efforts. Glycolysis breaks down glucose or glycogen, producing lactate, a focus of research by scientists like George Brooks. The oxidative system, dominant during prolonged activity, utilizes fatty acids and pyruvate within mitochondria via the Krebs cycle and electron transport chain.

Cardiovascular and respiratory responses

During exercise, the cardiovascular system undergoes profound changes to meet increased oxygen demand. Heart rate and stroke volume rise, increasing cardiac output, as described in the Fick principle. Blood flow is redirected from organs like the kidneys and liver to working muscles, a process mediated by the autonomic nervous system. Concurrently, the respiratory system increases minute ventilation through deeper breaths and a higher respiratory rate, enhancing gas exchange in the alveoli of the lungs.

Neuromuscular adaptations

Regular training induces significant adaptations in the nervous system and muscle tissue. Neural adaptations include improved motor unit recruitment and synchronization, enhancing strength. Within muscle fibers, protein synthesis increases, leading to hypertrophy of myofibrils containing actin and myosin. Endurance training boosts mitochondrial density and capillary supply, changes often studied in relation to fiber types classified by pioneers like Eric Hultman. These adaptations are central to protocols developed at institutions like the Karolinska Institute.

Environmental physiology

Exercise capacity is strongly influenced by environmental conditions. In heat, the body relies on thermoregulation via sweating and increased skin blood flow, a response studied by Per-Olof Åstrand. Altitude exposure, such as on Mount Everest, lowers partial pressure of oxygen, triggering adaptations like increased erythropoietin production. Research from organizations like the United States Army Research Institute of Environmental Medicine also examines performance in cold and humid climates, impacting guidelines for events like the Marathon des Sables.

Applications and testing

Applied exercise physiology involves precise assessment techniques. Cardiopulmonary exercise testing on treadmills or cycle ergometers measures maximal oxygen uptake (VO2 max), a concept popularized by Henry Taylor. Blood lactate testing helps establish training zones. These methods are used by the National Aeronautics and Space Administration for astronaut conditioning, by teams like FC Barcelona for athlete monitoring, and in clinics for managing conditions like chronic obstructive pulmonary disease. The field also informs public health guidelines issued by the World Health Organization.

Category:Physiology Category:Sports science