Figure 5 shows the stroke volume at different heart rates of a person who has trained for a marathon and of a person who has not trained for a marathon - Edexcel - GCSE Biology Combined Science - Question 5 - 2019 - Paper 1

The stroke volume of the person who has trained for the marathon is consistently higher than that of the person who has not trained. As the heart rate increases for the trained individual, the stroke volume increases as well. In contrast, for the untrained individual, the stroke volume tends to remain constant or increases slightly, indicating that the trained person has a more efficient cardiovascular response to increased heart rates.