Exercise physiology — AQA A-Level Physical Education

Exercise physiology is a core topic in AQA A-Level Physical Education that examines how the body responds to the demands of physical activity. It covers the acute responses of the muscular, cardiovascular, respiratory and energy systems during exercise, as well as the chronic adaptations that occur with long-term training. Understanding these processes is essential for explaining how athletes produce energy, delay fatigue and improve performance.

This topic also explores the recovery process, including the role of EPOC (excess post-exercise oxygen consumption), lactate removal and glycogen resynthesis. It links closely with biomechanics, skill acquisition and sports psychology, providing a scientific foundation for analysing and improving sports performance. Mastery of exercise physiology is crucial for both exam success and practical application in coaching and training.

• →Acute responses to exercise: immediate changes in heart rate, stroke volume, cardiac output, ventilation, blood flow redistribution, and energy system activation.
• →Chronic adaptations to training: long-term changes such as cardiac hypertrophy, increased capillarisation, increased mitochondrial density, increased oxidative enzymes, and improved respiratory muscle strength.
• →Energy systems: ATP-PC (phosphagen), lactic acid (anaerobic glycolysis), and aerobic system - their fuel sources, duration, intensity, ATP yield, and by-products.
• →Recovery: EPOC, lactate removal, glycogen resynthesis, and the role of cool-down and nutrition in speeding recovery.
• →Factors affecting fatigue: lactate accumulation, H+ ion build-up, PC depletion, glycogen depletion, dehydration, and thermoregulation.

• Aerobic training increases left ventricular cavity size and stroke volume, so cardiac output is maintained at a lower heart rate, improving cardiac efficiency.
• Increased capillary density and mitochondrial volume in trained skeletal muscle improve oxygen delivery, extraction and aerobic energy production.
• Strength training causes muscle hypertrophy and improved neural recruitment, increasing maximal force and power output.
• Regular activity lowers resting heart rate and can improve body composition, reducing the cardiac workload of everyday activity.
• Lifestyle factors such as smoking or inactivity impair gas exchange and vascular function, reducing the efficiency of the respiratory and cardiovascular systems.

• 💡Use the chain system change, then functional effect, then efficiency gain, for example larger ventricle, greater stroke volume, lower submaximal heart rate.
• 💡Distinguish training adaptations from lifestyle adaptations explicitly, because the statement names both.
• 💡Quantify where you can, such as a lower resting heart rate in beats per minute, to show precise understanding.
• 💡Check that every adaptation you name is matched to the correct system rather than listed generically.
• 💡Always use specific physiological terminology (e.g. 'sympathetic stimulation', 'Frank-Starling mechanism', 'mitochondrial density') rather than vague phrases like 'heart gets stronger'.
• 💡When answering questions on energy systems, state the predominant system for the given intensity and duration, and explain why it is predominant using specific details (fuel, ATP yield, by-products).
• 💡For 'explain' questions, ensure you link the physiological change to its effect on performance. For example, increased stroke volume leads to increased cardiac output, which increases oxygen delivery to muscles, delaying fatigue.

• Claiming cardiac output falls at rest after training: resting cardiac output is similar, but it is achieved through a larger stroke volume and lower heart rate.
• Confusing hypertrophy with hyperplasia: training mainly enlarges existing muscle fibres rather than increasing their number.
• Stating that training increases the number of heart chambers or lungs: the change is in size, volume, wall thickness and function, not in the number of organs.
• Treating all adaptation as immediate: structural change requires sustained training over weeks and reverses with detraining.
• Students often think lactate causes fatigue, but it is actually the accumulation of H+ ions (acidosis) that inhibits enzyme activity and muscle contraction. Lactate is a fuel source that can be oxidised.
• Students confuse acute responses with chronic adaptations. Acute responses occur during exercise, while chronic adaptations are long-term changes from training.
• Students believe the aerobic system only uses fat as fuel. In fact, it primarily uses glycogen and glucose at higher submaximal intensities, and fat at lower intensities.

1. 1Week 1: Create a table comparing the three energy systems (fuel, duration, intensity, ATP yield, by-products). Learn the acute responses to exercise for each system.
2. 2Week 1: Draw flow diagrams showing the cardiovascular and respiratory responses to exercise, including neural and hormonal control mechanisms.
3. 3Week 2: Make flashcards for chronic adaptations, grouping them by system (cardiovascular, respiratory, muscular, metabolic). Test yourself on the mechanisms and performance benefits.
4. 4Week 2: Practice exam questions on recovery (EPOC, lactate removal) and factors affecting fatigue. Use mark schemes to identify key terms you missed.
5. 5Ongoing: Watch videos of athletes training and try to identify the energy systems and physiological adaptations at work. Apply your knowledge to real sporting examples.

• 📋Short-answer questions (2-4 marks) asking you to define or describe acute responses or chronic adaptations. Advice: Be precise and use correct terminology; do not over-answer.
• 📋Extended writing questions (6-9 marks) requiring you to explain how a system responds to exercise or how training adaptations improve performance. Advice: Structure your answer with an introduction, clear paragraphs for each point, and a conclusion linking to performance.
• 📋Data analysis questions where you interpret graphs of heart rate, ventilation, or lactate levels during exercise. Advice: Read axes carefully, identify trends, and relate them to physiological mechanisms.
• 📋Application questions where you must suggest appropriate training methods to develop specific adaptations. Advice: Link the training type (e.g. continuous, interval) to the desired adaptation and explain why it works.