# Explain why the heart rate increases during physical activity.

> Cambridge International IGCSE Biology (0610) — 9.2 Heart · Explain · 4 marks

> During a 400 m race, a student's heart rate rises significantly from its resting value and remains elevated for several minutes after the race ends.

## Mark scheme (4 marks)

1. Muscles respire (more) during physical activity / muscles need more energy for movement
2. Aerobic respiration requires oxygen, so more oxygen must be delivered to the muscles / respiring tissues
3. A faster heart rate pumps blood around the body more quickly
4. This allows more oxygen (and glucose) to be delivered to / carbon dioxide to be removed from the respiring muscles / tissues

## Key terms

- [heart rate](https://www.gradenine.co.uk/glossary/heart-rate)

## Related

- [Revision notes for Cambridge International IGCSE Biology (0610)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
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Source: [GradeNine](https://www.gradenine.co.uk/q/explain-why-the-heart-rate-increases-1cba479d) · Published by Druglandscape Ltd.