Physiology and Exercise Physiology
What the domain covers
Exercise physiology examines how the muscular, respiratory, circulatory and nervous systems respond to exercise, both immediately and after training. The exam tests acute responses, chronic adaptations, energy systems and fatigue.
Core content
- Acute responses: heart rate rises, stroke volume rises, cardiac output rises, systolic blood pressure rises, ventilation and oxygen uptake rise, body temperature rises, and blood flow is redistributed to active muscles.
- Cardiac output = heart rate × stroke volume. At rest this is about 5 L/min; during maximal exercise it can reach 20–25 L/min.
- Chronic adaptations: lower resting heart rate, larger stroke volume, greater capillary density, more mitochondria, higher VO2max and better thermoregulation.
- Energy systems: ATP-PCr for roughly 0–10 seconds; anaerobic glycolysis for roughly 10 seconds to 2 minutes; oxidative system for longer work.
- EPOC is excess post-exercise oxygen consumption. DOMS is delayed-onset muscle soreness, typically 24–72 hours after unaccustomed exercise; it is not simply caused by lactic acid.
Worked example
A 100 m sprint is powered mainly by the ATP-PCr system because the effort is maximal and lasts under about 10 seconds. A 400 m race relies heavily on anaerobic glycolysis, with some oxidative contribution. A 5000 m race is predominantly oxidative. The reasoning uses duration and intensity, not the athlete's preference.
Traps that cost marks
Mixing up cardiac output and stroke volume; stating that lactic acid alone causes DOMS; treating energy systems as strictly separate; and forgetting that systolic pressure normally rises during dynamic exercise while diastolic changes little.