Taking part in the Virgin Money London Marathon is a pretty impressive feat in itself.

Runners of every shape and size will pound the pavements around Canary Wharf as they make their 26.2-mile journey towards the finish line.

Here are some surprising facts about runners who have completed the iconic distance in the past.

Read on to find out about why your spine shrinks when you run a marathon, how three runners covered 4,000 miles of Sahara desert and why the two-hour world record is just around the corner.

1) Running the marathon burns more than a day’s worth of calories

While weight, gender and speed all play a part, the widely-held view is you burn 100 calories per mile giving a whopping total of 2,620 calories destroyed during a marathon. That’s a lot of leftover Easter chocolate.

2) The 100 Marathon Club is a real thing

Entry is reserved to runners from the UK and Ireland that have completed 100 marathons or more. Last year 77 runners joined. The club record is held by Brian Mills who has completed an impressive 1,000 marathons. While the club’s quickest 0 to 100 marathons record is held by Philip Rand who accomplished this in a speedy 450 days.

3) The fastest

The average marathon time is 4 hours 18 (men) or 4 hours 44 (women).

Dennis Kimetto of Kenya holds the men’s world record of 2:02:57, while Paula Radcliffe is the women’s record holder, running 2.15.25 at the 2003 London Marathon and finishing the last 800m in two minutes and 25 seconds. Compare that to the 880m British record of one minute 56 seconds held by Kelly Holmes.

Nike’s Breaking Two project will attempt to create perfect conditions and break the two-hour record at the Formula 1 circuit in Monza, Italy in May.

4) 100-year-old marathon runner

The oldest marathon runner is Fauja Singh, born in 1911, he ran the 2011 Toronto Waterfront Marathon aged 100 in a time of 8 hours, 11 minutes.

Eight years earlier, he set the marathon record for the 90+ category in a time of five hours, 40 minutes.

5) The biggest marathon

The NYC Marathon holds the record for the largest number of participants, set in November 2016 when 51,388 runners from 124 countries finished the race which gained 18million impressions on Facebook.

6) The coldest marathon ever was -38C

Boris Fyodorov completed a marathon in -38C

Boris Fyodorov completed his first marathon as a solo, out-and-back run from Oymyakon, in Russia, the coldest settlement on the planet on New Year’s Day 2014 in a time of 5:08:00

7) Olympic marathons for women didn’t start until 1984

Joan Benoit Samuelson won the race in a time of 2.24. It’s now believed women are actually better suited both physically and mentally than men to running long distances.

8) A Chilean miner trained while trapped underground

Edison Pena, trained for his first marathon while being trapped in the 2010 Chilean mine accident. He was trapped for more than two months with 33 other miners and spent his time running six miles a day. He completed the New York marathon less than a month after being rescued.

9) 4,000 miles across the Sahara

In 2007, three runners ran the entire distance of the Sahara. They ran two marathons a day for 111 days to cover 4,000 miles from Senegal to the Red Sea, running from 4am until 9.30pm each day through intense heat and wind.

10) A marathon makes you shorter

You could be up to half an inch shorter after a marathon, as the discs in your back actually leak water and become shorter under the repetitive strain of around 50,000 steps. But don’t worry, the result is only temporary and research has shown that running can actually help form new disc cells and avoid disc degeneration.

If these incredible stories have inspired you to take on the challenge of a marathon, check DW Fitness Clubs’ 26 tips to survive a marathon.

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