Response to Exercise

During exercise, the body's demand for energy increases dramatically. This lesson explores how the body responds to exercise to meet this increased demand, including changes to heart rate, breathing rate and blood flow, as well as the concept of oxygen debt and the recovery period. This is a key topic for AQA GCSE Biology.

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Why Does the Body Need More Energy During Exercise?

When you exercise, your muscles contract more frequently and more forcefully. This requires more energy, which comes from aerobic respiration:

glucose + oxygen ---> carbon dioxide + water (+ energy)

To increase the rate of aerobic respiration, the muscles need:

• More glucose — to be broken down as fuel
• More oxygen — to react with the glucose
• Faster removal of carbon dioxide — which is a waste product that would lower the pH and inhibit enzymes if it accumulated

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How the Body Responds to Exercise

The body makes several automatic adjustments during exercise to increase the delivery of oxygen and glucose to the muscles and to remove carbon dioxide more quickly.