Ideal running weather is cloudy and in the 50s, which means the biggest marathons usually happen in the fall before it gets too cold and in the spring before it gets too hot. Thus, the Paris, London, and Boston marathons (in that order) will all be run this April.

Typically, Paris doesn't make it into the same sentence (or article) as London and Boston, two of the world's five major marathons (along with New York, Chicago, and Berlin). This year's, however, features the 26.2 debut of living track legend Kenenisa Bekele, who seems like he's 35 to 40 by now but is actually only 31. Bekele broke his own 10,000 meter world record (26:17; 5k splits of 13:09 and 13:08) and also set the current 5,000 meter world record (12:37) about a decade ago. Since then, he's won a few gold medals and suffered a host of injuries. Over the last few years, he's wagered something of a comeback, but hasn't yet returned to his previous form.

Still, his entry into Sunday's Paris Marathon is a big deal.

"Usually it's not in our policy to have the best marathon runners," Thibault Vellard, the race director, told the New York Times. "We are more focused on the mass, the 49,999 people running, except for a Bekele. But we had the opportunity to have him for his first marathon, and you only have one first time, and so it was a great opportunity and that is why we decided to change our policy."

Current king of the track Mo Farah (Olympic gold medalist in the 5,000 and 10,000 meters) will also run his first marathon when London's version begins next Sunday. (He's 31, too.) Since he's had more recent success than Bekele, his participation is an even bigger deal.

"Recently, Kenenisa's performances have not been what they were in 2008 or 2009," said Ken Nakamura, a marathon statistician (didn't know that title existed). "If he had made his debut in 2010, after his back-to-back doubles, that would have been really big. But in that sense, Mo is now in that position, and he is making his debut in his home country, which makes it even bigger, as does the fact that the London Marathon is more prestigious than Paris."

Farah and Bekele's 30-and-over debuts used to be the norm, until the money shifted from the track to the roads. Today, many runners (usually African) start running marathons in their teens.

The Boston Marathon is on April 21.