Exercise Physiology, Energy Systems and Training
Exercise Physiology, Energy Systems and Training
This domain links acute responses and chronic adaptations to the three energy systems. Candidates must know the ATP-PCr (phosphagen) system (immediate, about 10 seconds, no oxygen, no fatiguing by-products), anaerobic glycolysis (short, high intensity, produces lactate and hydrogen ions, roughly 10 seconds to 2 minutes) and aerobic system (long duration, oxygen-dependent, large ATP yield, uses carbohydrates and fats). Understand the interplay: all systems contribute at all times, with dominance shifting by intensity and duration. Know acute responses (heart rate, stroke volume, cardiac output, ventilation, blood pressure, temperature, sweating) and chronic adaptations (cardiac hypertrophy, increased stroke volume and capillary density, mitochondrial and enzyme changes, improved lactate tolerance).
Understand training principles: specificity, overload, progression, reversibility, individuality, variety, recovery and periodisation. Know FITT (frequency, intensity, time, type) and methods including continuous, interval, fartlek, resistance, plyometric and flexibility training, plus how each targets a system. Know VO2 max, lactate threshold, steady state, oxygen deficit and excess post-exercise oxygen consumption.
Traps
Claiming one system works alone; confusing lactate with lactic acid as the sole cause of fatigue; assuming fat is used only at low intensity (it is used across intensities, but proportionally less as intensity rises); and mixing acute responses with chronic adaptations. Another trap is applying overload without recovery.
Worked example
A 400 m sprint lasts about 50-60 seconds. Anaerobic glycolysis dominates, with ATP-PCr at the start and aerobic contribution rising late. Rule of thumb: under 10 seconds, ATP-PCr; 10 seconds to 2 minutes, glycolysis; beyond 2 minutes, aerobic dominance. Train the dominant system with matching work-to-rest ratios: short sprints with long rests for ATP-PCr; repeated efforts with incomplete recovery for glycolysis.
Rule of thumb
Match the training method to the energy system and the sport's work-to-rest profile.