How does exercise affect my heart?

Mat Brett explains the key effects and adaptations exercise has on your cardiovascular system

Credit: Science Photo Library - PASIEKA / Getty Images

Follow a structured endurance training programme with effective recovery between your sessions and you can expect your cardiovascular system, which includes your heart and blood vessels, to adapt in many ways. Here are some of the key ones that will affect your athletic performance…


Heart size

Your cardiac muscle will develop and your heart will grow in volume. Essentially, your heart will become larger and more powerful, so it’ll be able to pump more blood around your body.

Stroke volume

Your heart’s stroke volume is the amount of blood it pumps with every beat, and this will increase. That means that, for any given heart rate, your heart will pump more blood around your body than if you didn’t train.

Heart rate

As your heart becomes stronger, your heart rate will decrease for a given level of exercise. So, say you start off being able to run 10km in 45mins with an average heart rate of 150 beats per minute (bpm), after a period of regular training you might be able to run the same distance in the same time with an average heart rate of 140bpm. Or, if you
still run for 45mins with an average heart rate of 150bpm, you might go significantly further than 10km.

Your heart will pump more blood around your body with each heartbeat, so your resting heart rate will drop, too. A typical resting heart rate in adults is about 60-90 beats per minute (bpm) but many endurance athletes have lower figures. 

After a period of regular training, your heart rate will likely return to normal after exercise more quickly than previously, too.

Blood flow

Good aerobic training will ensure your working muscles get a higher blood supply during exercise. You’ll develop the network of capillaries – tiny blood vessels – in your muscles, so that they are able to receive oxygen, fuel and nutrients more effectively.

Blood volume

Training can increase your blood volume. This is largely down to more plasma but the number of red blood cells will also rise.

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