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What happens to your body when you run a marathon

Running a marathon is a huge physical and mental challenge and those 26.2 miles are going to have a big impact on your body, from your brain to your big toe. While most runners will be aware of the potential for cramp, sprains and sheer exhaustion there are other body consequences that you may not expect.

Brain training

Running a marathon can take real mental toughness and determination but it may also help your brain function. A study showed that endurance running alters the way the brain communicates with the body, with the muscles of distance runners responding more quickly to signals from the brain than those of people who were sedentary or lifted weights. So running really can make you in tune with your body.

All ears

Old man shouting I heard that | DNAfit Blog

Don’t whisper about a marathon runner, because the chances are they’ll hear you! Training for and running long distances can increase circulation to the ear. Research showed that runners had significantly improved hearing sensitivity after they’d finished their run. This is believed to be due to the better blood supply providing more nutrients and removing waste products more efficiently.

Snuffles and sneezes       

More than half of people find their nose runs as fast as they do when running outside for long periods. A study showed that exercise-induced rhinitis, also known as runner’s hayfever, is a common problem even in individuals who don’t usually suffer from allergies. Scientists believe it could be due to the air flowing through your nose at a quicker rate, when you’re running a marathon due to the body’s increased oxygen requirements. The cells lining the nose respond to this stimulus with a flood of mucous, especially if the air is cold or dry. This mucous is what’s making your nose feel stuffy and your nostrils drip.

Coming up short

You may find that you finish a marathon a little shorter than you were when you started it. It’s not that the pavement pounding has worn your legs down, it’s actually due to shrinkage in the spinal column. Your body loses water throughout the race due to sweat and increased respiration, the decreased body fluid can cause the discs between the vertebrae to shrink by as much as 2cm overall. But don’t panic, regular running won’t leave you shrunken, you’ll return to your normal height as soon as you rest and rehydrate.

Exhausted marathon runner | DNAfit Blog

A weight off

Most runners are a little lighter as well as shorter after they’ve completed those 26.2 miles. Depending on your size you can expect to lose between two and five kilos during the race. Now, that’s not down to burning off calories, it’s due to all the fluid your body has lost. Gentle slow rehydration, until your urine is the colour of pale straw is the key to recovery. Don’t make the mistake of drinking too much during the race to prevent dehydration. Research shows that many more people are hospitalised due to having too few salts because of over drinking, than are from talking in too little fluid.

All that exercise and exertion will burn off calories, somewhere between two and three thousand depending on your size. You will also empty your body’s ready supply of energy, glycogen, you’ll know when that happens because it’s when you hit the infamous ‘wall’ at around twenty miles. You can replenish your glycogen stores with by eating about 1g of carbohydrate for each kilo of body weight a few hours after the finish. That’s a light meal, not a free pass to gluttony!

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Top to toe

I started this blog saying that your body would be affected from brain to big toe and I’ll finish with the marathon’s impact on your feet.

The average runner takes more than thirty thousand strides and that is tough on the two body parts that take much of the strain. Blisters and broken blood vessels are par for the course, even if you have well-loved, supportive and comfortable trainers.

Some research has also suggested that black and bruised ‘jogger’s toes’ are also common, affecting as many as 14% of participants in one marathon. Toenail injuries happen because of repeated impact and are made worse if your foot can slide, even fractionally, inside the shoe. In fact one veteran runner told me that she marked the end of every race with the loss of another toenail. Fortunately there was always a fresh, new one waiting to appear so it was a price worth paying, for the sheer exhilaration and ecstasy of crossing the finishing line.

To help you run marathons better learn more about your power and endurance profile with Body Fit - a personalised easy to follow plan for those actively working on their fitness. 

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