Reasons to run
Regular exercise such as running keeps you happy and healthy, inside and out. But why is it so good for you? Here are some of the benefits of running and the science behind how it improves the way your body works.
Increases the flow of blood and oxygen around your body
What happens?
When you run, your heart rate (the number of times your heart beats per minute) and stroke volume (the amount of blood your heart pumps out with each beat) increase, improving the flow of blood around your body. Because your blood carries oxygen, this helps supply your muscles with the oxygen they need during exercise.
How does this help me?
The amount of blood and oxygen your heart pumps out every minute is called your cardiac output (CO). Your CO will increase with training, so every heartbeat will supply your body with more oxygen than before.
A higher CO means you’ll be able work harder to improve your performance during training runs, but it will feel like the same amount of effort as before your CO increased. For example, if running a mile in 10 minutes takes your heart rate up to 160 bpm (beats per minute), after a few weeks of training you’ll be able to do the same run with your heart rate peaking at 140bpm.
Similarly, when you’re resting, your heart rate will drop because your body will be working more efficiently.
Your muscles absorb more oxygen from your blood
What happens?
Exercise triggers the growth of capillaries (tiny blood vessels) in your muscles. A regular runner will have an average of five to seven capillaries per muscle fibre, while a non-runner will only have three to four.
How does this help me?
Capillaries let water, oxygen, carbon dioxide, nutrients and waste products pass between your blood and muscles. Having more capillaries means your muscles can get more oxygen and nutrients – and easily offload waste products and gases – when you exercise.
The maximum rate at which your muscles can take oxygen from your bloodstream is known as your VO2 max. Although your sex, age and genetics affect your VO2 max, it will increase when you run regularly.
Your body produces energy more efficiently
What happens?
As you get fitter, the number of mitochondria (energy-producing cells) in your muscles increases.
Exercise can also increase the amount of red blood cells in your body – improving the flow of oxygen to your mitochondria and helping them produce energy more efficiently.
How does this help me?
Mitochondria release energy from the breakdown of a substance called adenosine triphosphate (ATP). If there isn’t enough oxygen in your bloodstream the mitochondria can’t work at their best, so ATP has to be broken down without using oxygen. This can cause a build-up of lactic acid in your muscles when you exercise.
If lactic acid is produced more quickly than it can be removed from your muscles, you cross your ‘lactic threshold’. At this point, your legs will start to feel stiff and heavy, your stomach will churn and you’ll probably be telling yourself you can’t go on.
So, in summary, the more you train the better your body becomes at producing energy, which means you can train harder and for longer before you feel like you have to stop.
Your body starts to burn fat
What happens?
Regular exercise conditions your body to use fat as an energy source instead of carbohydrate.
How does this help me?
Because your body starts burning fat for energy, you’ll have less of it on your body. Not only will you start to feel better, having less fat internally around your heart can improve your overall health and life expectancy.
And while your body’s using fat for energy, it isn’t using the carbohydrate you’ve stored as glycogen. This is more efficient because your body can only store a limited supply of glycogen, while fat is more readily available.
