5 Surprising Things That Happen To Your Body During A Marathon

Taking part in the London Marathon this April? No doubt you’re racking up some impressive mileage each week to prepare your body to take on the notoriously tough challenge. But however much training you do, and whatever your ability level, there are certain common side effects to expect while running for 26.2 miles. Read on to find out what happens to your body during a marathon (and don’t let this put you off: there’s no better feeling than picking up your medal after crossing the finish line).

What Happens To Your Body And Mind During A Marathon?

You’ll temporarily get shorter

The rumours are true: during a marathon, you’ll get shorter. Several studies have found you can lose up to half an inch of height while completing the challenge – but fear not, it’s only temporary. There are a number of factors behind this, including muscle tension and the loss of fluid between your intervertebral spinal discs.

Your brain might start ‘eating itself’

In general, running offers an abundance of benefits for brain health, but during the run itself, it may start to ‘eat’ its own fatty tissue, myelin, as a source of energy. These new findings come from a study published in Nature Metabolism, which looked into the brains of marathon runners. However, the scientists involved said it shouldn’t be a cause of concern, as the myelin reduction only lasts for a short time – and, indeed, the process teaches the brain how to repair myelin, which could be beneficial. 

You may cry

We’ve all heard of the runner’s high, but what about the runner’s cry? Many marathon runners find themselves feeling teary during the race, which is not really surprising – you’re taking on an incredibly tough challenge while thousands of spectators cheer you on. But there’s also a scientific reason: studies show extreme fatigue can lower the threshold for crying.

You may lose your appetite

The thought of a giant pizza might be getting you through those last few miles, but don’t be surprised if you find it takes a while for your hunger to kick in afterwards. That’s because intense exercise suppresses the hunger hormone, ghrelin. Plus, it’s common to feel sick after a marathon – a result of dehydration, which can reduce blood flow to the stomach and GI tract, triggering nausea.

Getty Images

You’ll experience the post-marathon blues

During training, you’ll likely be daydreaming about not having to run multiple times a week. But afterwards, you may find you miss it. After spending the evening celebrating, followed by a huge sleep, many marathon runners feel a bit flat for a few days, known as the post-marathon blues. Running releases chemicals called endorphins, which increase feelings of happiness, so when training levels drop dramatically the body sometimes experiences a dip in mood. Plus, your life has been building up to the marathon for weeks, so it can feel like a bit of an anti-climax. But don’t worry, this usually subsides in a few days… by which time you’ll be ready to sign up to the next one!