# How does exercise affect heart rate?

## How does exercise affect heart rate?

This activity is a great way to introduce correct scientific procedures, thinking about variables to change and keep constant.

Exercise increases the rate at which energy is needed from food, increasing the need for both food and oxygen by the body. This is why when we exercise both pulse/heart rate and breathing rate increase.

Pulse rate is  an indication of your heart rate as your arteries expand each time the ventricles pump blood out of the heart.

The heart speeds up to pump extra food and oxygen to the muscles, while breathing speeds up to get more oxygen into the body and remove carbon dioxide.

Step 1

Use the stethoscopes and timers to record how many heartbeats you can hear in 30 seconds.

Step 2

Exercise – this could be 30 seconds of star jumps or a mini obstacle course.

Step 3

Use the timers and stethoscopes again to record how many heartbeats you can hear in 30 seconds.

Let’s think scientifically

A scientific investigation should be a fair test, think about what conditions you need to keep the same and what condition you will change. You should also repeat the testing 3 times and find the average heart rate.

Things to keep the same:

Heartbeats must be counted before and after exercising for the same amount of time.

The person whose heart rate is compared must be the same.

Things to change:

Heart rate should be measured before and after exercise.

Make a prediction

What effect do you think exercise will have on heart rate?

Why do you think this?

Clue – when you exercise your muscles need more food and oxygen from your blood, so your heart has to beat faster to transport them.

What is recovery time?

Recovery time is the time taken for heart rate to return to normal. If you have time, can you work out how long this is for you?

The pulse rate and breathing rate of a fitter person rise much less than in an unfir person during exercise, fitter people also have a shorter recovery time.

Design a method of recording your results? Can you work out the average heart rate for 10 participants before and after exercise?

Calculate the difference between a person’s heart rate before and after exercise.

Can you write a letter to a friend telling them about your findings?

Extension activities