What happens when you choose to lace up a pair of running shoes to make the leap from couch potato to race race finisher?

Here are 5 ways that running will change your body and improve your health.

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1. Changes to muscles and mitochondria happen

The first changes will start to happen in your muscles as your body produces more small structures called ‘mitochondria’, which use oxygen to produce energy.

At the same time, the number of blood capillaries that supply leg muscles with oxygenated blood will increase in number and penetrate deeper into the muscle to supply more oxygen-rich blood to working muscle fibres.

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2. Cardiovascular function improves

Running is one the most effective activities to strengthen your cardiovascular and respiratory systems. From the first step, your heart will work harder to pump more oxygenated blood to your leg muscles and back up to the heart and lungs.

This increased workload will start to strengthen your heart (cardiac) muscle. As you run farther, faster and more often, this form of exercise will strengthen the walls of your heart, which increases its overall efficiency.

That means it is able to pump more blood around the body with every beat. As a consequence, you should start to see you resting heart rate decrease over time and, as your fitness levels improve, your average heart rate will drop for the same effort.

Your lungs will also become more efficient as they transfer more oxygen to the additional blood your heart delivers to these structures with every beat.

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3. Your bones become denser

This weight-bearing activity is also one of the quickest and most effective ways to improve your bone density.

Loading your legs with every step causes your bones to strengthen over time and drives changes in bone mineral density by increasing the amount of calcium deposited there, provided your diet and supplement plan provide sufficient amounts of this important mineral.

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4. Your metabolism will get a boost

When we start running, our metabolism increases to support the increased energy demands we place on our muscles.

This helps us burn more calories, which will eventually start to reduce our body fat levels (provided we eat appropriately to create a negative calorie balance and limit processed carbs and sugar).

Once you’re able to run for an hour, you can burn as much as 800 calories in that time, depending on your speed and the terrain run on and over.

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5. Brain benefits

Running will immediately start to positively impact your mental health by releasing hormones called endorphins.

These ‘feel-good’ hormones, which include serotonin and dopamine, are associated with a drop in stress hormone levels, which helps to improve mood and combat depression, stress and anxiety.

Research1 also shows that running can boost brain function by improving brain plasticity – it’s ability to change – as aerobic exercise promotes new brain cells and also promotes new connections (neurons) between cells in various important areas of the brain.


  1. Running Changes the Brain: the Long and the Short of It. Physiology (Bethesda). 2017 Nov; 32(6): 410–424. Published online 2017 Oct 11. doi: 10.1152/physiol.00017.2017