Oxygen Uptake
What is oxygen uptake?
The amount of oxygen the body uses during exercise/ physical activity.
What happens to HR when exercise begins?
It increases.
Identify the main energy system contributor in the 100m sprint.
ATP-CP system
Name one cause of muscular fatigue.
Fuel depletion, H⁺ accumulation, or thermoregulatory fatigue
What is glycogen?
Stored form of carbohydrate in muscles and liver
Define steady state.
When oxygen supply meets oxygen demand
Identify one respiratory change during exercise.
Increased RR
Increased TV
Increased V
Increased Pulmonary Diffusion
Increased Oxygen Uptake
Which energy system produces lactic acid (H⁺)?
Anaerobic Glycolysis system
How does dehydration contribute to fatigue?
Reduces blood volume (loss of plasma through sweating), blood becomes more viscous = slower oxygen delivery.
Why is fat not ideal for high-intensity exercise?
It is slow to break down for energy
Define oxygen deficit and explain when it occurs.
When oxygen supply is less than oxygen demand. Occurs at the beginning of exercise.
How does stroke volume change during exercise?
It will increase linearly with HR as intensity increases. It will then plateau at around 60%MHR
Compare the ATP yield of anaerobic glycolysis and the aerobic system.
Anaerobic glycolysis produces a moderate amount of ATP; aerobic produces a high amount.
What is the most likely cause of fatigue for a runner completing the 400m hurdles event in 50.68s?
Accumulation of metabolic by-products
Explain how carbohydrate ingestion delays fatigue.
Maintains blood glucose and glycogen stores, allowing continued energy production
What is EPOC and why does it occur?
Excess post-exercise oxygen consumption; elevated oxygen intake after exercise to restore the body (e.g. replenish ATP-PC, remove lactate, restore oxygen stores).
Explain how blood flow is redistributed during exercise.
Blood is redirected away from non-essential organs (e.g. digestive system) and towards working muscles via vasodilation in muscles and vasoconstriction elsewhere.
Describe how energy system contribution changes during a 1500m run. (approximately 4 minute duration)
Aerobic system dominant; anaerobic glycolysis contributes during surges; ATP-PC used at start and sprint finish.
How does fuel depletion affect endurance performance?
Reduced glycogen leads to decreased energy production and intensity.
Identify a nutritional strategy used before physical activity and explain why it is beneficial to performance.
Carbohydrate loading
Increases muscle glycogen stores, allowing sustained energy production and delaying fatigue
In a 400m race, will the runner reach steady state? Justify your answer.
No, a runner will not reach a steady state in a 400m race.
A 400m race is too short, too fast, and too reliant on anaerobic energy systems.
Analyse how increased cardiac output and ventilation work together to improve oxygen delivery during high-intensity exercise.
Increased cardiac output delivers more oxygenated blood to muscles, while increased ventilation improves oxygen uptake in the lungs; together they maximise oxygen delivery and performance.
Analyse the interplay of all three energy systems during an intermittent sport such as basketball.
ATP-PC for short bursts (sprints/jumps), anaerobic glycolysis for repeated high-intensity efforts, aerobic system for recovery and overall energy supply.
Compare fatigue in marathon vs 200m sprint.
Marathon: glycogen depletion, dehydration, heat; 200m: H⁺ accumulation and ATP-PC depletion.
Justify the importance of combining carbohydrates and protein post-exercise.
Carbs restore glycogen, protein repairs muscle → faster and more effective recovery. Greater insulin response when ingested together.