# During a sprint race, a runner's muscles respire anaerobically. Explain what happens to the lactic acid that accumulates in the muscles during the race.

> Cambridge International IGCSE Biology (0610) — 12.3 Anaerobic respiration · Explain · 4 marks

## Mark scheme (4 marks)

1. Lactic acid is transported to the liver
2. Lactic acid is oxidised / broken down using oxygen
3. This requires extra oxygen, creating an oxygen debt
4. Breathing rate / heart rate remains elevated after exercise to supply the extra oxygen needed

## Key terms

- [lactic acid](https://www.gradenine.co.uk/glossary/lactic-acid)

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Source: [GradeNine](https://www.gradenine.co.uk/q/during-a-sprint-race-a-runner-s-e6d1ee2f) · Published by Druglandscape Ltd.