CAIE IGCSE Biology 9.2.11 Why Exercise Raises Heart Rate
Practise explaining the increased heart rate during exercise from muscle respiration and transport demands.
- Syllabus
- 2026–2028
- Course
- Biology 0610
Exam points
- link contracting muscles to increased energy demand and a higher rate of aerobic respiration
- explain that faster blood flow supplies more oxygen and glucose and removes more carbon dioxide
- interpret closer ECG peaks as increased beat frequency and recognise adrenaline as a contributing signal
9.2.11—Effect of physical activity on question 1
A group of students investigated the effect of exercise on their heart rates.
They measured their heart rates:
- before exercise
- immediately after running 1 km
- one minute after running 1 km
Before doing the investigation they wrote a hypothesis.
The doctor divided her coronary heart disease patients randomly into two equal groups.
Each group was given different instructions:
- group A - patients were given a daily exercise plan
- group B - patients were told to make their own exercise plan.
The doctor measured the heart rate (HR) of each patient immediately after doing exercise and again one minute later.
She calculated their heart rate recovery using this formula:
heart rate recovery = HR immediately after exercise - HR one minute after exercise.
She then calculated the average heart rate recovery for each of the two groups of patients.
The doctor repeated these measurements after three months and after six months.
The results are shown in Fig. 2.1.
Fig. 2.1
Describe and explain the effect of exercise on the average heart rate recovery of the coronary heart disease patients in group A and group B.
Use data from Fig. 2.1 to support your answer.
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