For fans of distance running, April means one thing: marathons. From Boston to London, Hamburg to Paris, they're about to arrive thick and fast, with some of the sport's heavyweights set to clash at the ultimate distance. Here's your ultimate guide to what's happening, where. 

Bekele gunning to be the greatest in London

In the debate about the best distance runner in history, there seems no right answer, such are the varied accomplishments of the chief contenders spanning the different generations. Nurmi, Zatopek, Viren, Gebrselassie, Bekele – the argument goes on ad infinitum, each person staking a reasonable claim to the throne.

However, if Kenenisa Bekele takes victory at the London Marathon on April, and makes good on his promise to eventually break the world record, then the debate should end there and then.

Because such is the depth and breadth of Bekele’s accomplishments – three Olympics golds, five world track titles, 11 world cross country titles and the existing world records for 5000m and 10,000m – that ascending to the throne in the marathon should see him crowned the undisputed king.

Last year, Bekele finished third in London in 2:06:36, which wasn’t deemed enough for Olympic selection by Ethiopian selectors. Fuelled by the fire of missing out, he showed them what they were missing in Berlin, running 2:03:03 to beat Wilson Kipsang and miss the world record by just six seconds.

In Dubai earlier this year, an early fall put paid to his world record attempt, but Bekele is in confident form ahead of his return to London, where he will square off with Kenya’s Stanley Biwott, who was second last year in 2:03:51.

“London is the greatest marathon in the world and I would love to win there,” said Bekele. “After finishing third last year, I know what I need to do to win.”

The women’s race feature perhaps the strongest line-up ever assembled for a marathon, with two-time champion Mary Keitany taking on Olympic bronze medallist Mare Dibaba, Chicago champion Florence Kiplagat and Olympic 5000m champion Vivian Cheruiyot.

Keitany can lay claim to top billing, courtesy of her PB of 2:18:37. Though she is now 35 and undoubtedly entering the autumn of her glittering career, she proved she is quicker than ever when running 65:13 to finish second at the Ras Al Khaimah half marathon in February.

An intriguing entrant is Ethiopia’s Tirunesh Dibaba, who ruled the 10,000m for the best part of a decade, but has yet to transfer her outstanding ability to the marathon. Dibaba made a promising debut in London three years ago, then returned to the 10,000m, where she took a bronze medal at the Olympic Games last year. Though she was well beaten into fifth at the Ras Al Khaimah half marathon in February, running 66:50, the baby-faced destroyer is too big a talent to write off in any race.

Mary Keitany on her way to victory at the 2012 London Marathon

Who can handle the heartbreak in Boston?

There’s nowhere quite like Boston, at least not when it comes to logging 26.2 miles. The point-to-point course winds its way from Hopkinton to downtown Boston over rolling hills before finishing up on Boylston Street, where the world’s most enthusiastic supporters come out in their thousands to roar their support for the weary runners. 

As the saying goes, the marathon only starts at 20 miles, and that, coincidentally, is when runners in Boston will crest the ascent known as Heartbreak Hill. After they coast down the other side, who will make the decisive, race-winning move come 17th April?

The men’s field is loaded, featuring four 2:04 men, one 2:03 man… oh, and a 2:02 guy.

That, of course, is world record holder Dennis Kimetto, who will try to fend off fellow Kenyan Emmanuel Mutai (the 2:03 man) and a host of other East African talent.

The home charge is headed by Galen Rupp, the Olympic marathon bronze medallist, who will look to give the US their first win in the race since Meb Keflezighi in 2014. 

The women’s field is headed by Kenyans Edna Kiplagat and Gladys Cherono, who have both run below 2:20 at their peak. New York-based Ethiopian Buzunesh Deba will be hoping to emulate her victory in 2014, where she set the course record of 2:19:59.

While Shalane Flanagan has had to withdraw with injury, hopes are still high for the home fans with Desiree Linden entered again and Jordan Hasay – who clocked a swift 67:56 half marathon in Prague last weekend – set to make her marathon debut.