The gruelling 26 miles of a marathon will trigger blood, sweat and tears in many runners.

But how exactly does running such a distance affect the body?

Here, ahead of the London Marathon this Sunday, experts have revealed what effect this level of exercise has on us...

Ahead of the London Marathon, experts have revealed what effect this level of exercise has on the body

'During a marathon and other high intensity, endurance sports the body goes through intense conditions,' says Dr Agim Beshiri, medical director at the global healthcare company Abbott.

'But, with the appropriate conditioning and training, it body manages to adapt and rise to the challenge.

'For instance, some organs can withstand significant reductions of blood flow for short periods of time as the body automatically prioritises circulation to the heart, brain and muscles during a marathon.'

YOU'LL SHRINK

The average marathon runner will be about 1cm shorter at the end of the race than when they began.

This is because over time, the discs in the vertebrae compress, researchers at Swansea University found.

However the height decrease is naturally reversed in about one day’s time.

YOU'LL LOSE 3LB

Most runners will lose 2-3 pounds of body mass during the course of a marathon.

An average person sweats between 0.8 to 1.4 liters per hour during exercise, according to the Boston Athletic Association.

This equates to between 3.4 and 6 litres of sweat for the whole race.

A new study has found marathon runners tend not to remember the gruelling pain they experience completing the 26.2 mile challenge. It comes as thousands prepare to take to the streets of London this weekend for the annual Virgin London Marathon

YOUR HEART WILL PUMP UP TO 16 LITRES OF BLOOD

The heart is a pump that is made up of around a half a billion cells, explains Dr Agim Beshiri, medical director at the healthcare company Abbott.

'Cardiac output in a normal individual at rest ranges between 4 to 6 litres per minute.

'But during a marathon, the heart is required to pump three to four times this amount.

MARATHON FIRST AID BY NUMBERS It takes a few tons of equipment and supplies to get runners to the finish line healthy, safe and hydrated. Here are the items that will be on hand: * 2,000 plasters * 250 tubes of petroleum jelly * 40,000 foil blankets to ward of hyperthermia * 1,250 portable toilets * 750,000 bottles of water Advertisement

YOU'LL IMPROVE YOUR MEMORY

A new study from the Salk Institute in California found the same bodily process which helps fuel the body efficiently for running is also responsible for improving memory and learning.

This means marathon runners may have better memory than the average person, the reasearchers suggest.

YOU'LL BE MORE ATTRACTIVE

Scientists at Cambridge University recently found that people who are better at running half marathons are likely to have been exposed to high levels of testosterone in the womb.

This means they not only have better cardiovascular efficiency but also a strong sex drive and high sperm count - suggesting that historically they were chosen by women as more desirable mates.

SO WHAT SHOULD YOU EAT BEFORE THE MARATHON?

Pamela Nisevich Bede, sports dietitian at Abbott, told MailOnline...

DO: Fight off injuries and inflammation with Tart Cherries and Tart Cherry Juice

Research has found that intake of this emerging superfruit can lead to reduced inflammation, reduced pain from gout and arthritis, and an extensive list of heart health benefits.

DO: Get your coffee hit

Contrary to popular belief, there is no need for runners to cut out coffee from their diets.

Studies show that supplementation of caffeine (between 3-6mg/kg) is effective in reducing perceived exertion.

Beetroot can help with blood flow and muscle contraction, while coffee can reduce how difficult running feels

DO: Naturally improve your performance with beets

Beetroot is a rich source of inorganic nitrate- which your body converts to nitric oxide. It then uses it as a vasodilator to assist in blood flow, muscle contraction, neurotransmission, and much more.

DO: Have a cuppa for better health and performance

Tea contains hundreds, if not thousands, of bioactive compounds, including potent health protectors like flavonoids, and is naturally calorie-free.

DON'T: Cram for a race

Races aren’t like exams- you can’t pull an all-nighter (or train hard in the days beforehand), hoping to perform well when the true test arrives.

DON'T: Consume the wrong blend of nutrients:

You know that without enough carb, your race day efforts might fall short. But did you know that too much fat or too much fibre can also derail your day?