Tens of thousands of runners will take to the streets of Montreal this Sunday for the Montreal Marathon.

They'll hit the streets at 8 a.m. and the slowest runners will cross the finish line by 2 that afternoon.

In addition to the 42 km distance for the full marathon, there will also be runners doing completing 1K, 5K, 10K and 21km distances.

Chris Ochiai manages the Running Room in Westmount and says new runners notice they just feel better and have more energy, adding often it takes just a few runs before they're hooked.

“We find that even the people from the five- and 10-kilometre clinics have now moved up to the half marathon. These tend to be one of the fastest growing events in Canada,” he said.

This year’s Montreal Marathon will be the biggest yet, and it's not just Montrealers taking part – there will be around 34,000 runners participating from all over the world.

"They're combining their fitness, their travel, their passion for healthy lifestyle with the music. It really is a 26.2-mile block party," said Dan Cruz, an organizer with the marathon.

Of course every event in Montreal requires streets to be closed for the duration, and the marathon is no exception, with roads closed in Jean Drapeau Park, the Old Port, and north from La Fontaine Park to Villeray Park, and as far east at the Olympic Stadium.

The most significant closure is the Jacques Cartier Bridge, which will be off-limits from 4 a.m. to noon on Sunday.

What makes this year's event unusual is that the normal route is being changed to accommodate detours for road construction.

"Yes there will be orange cones, yes there will be 35,000 people and we will be showcased, but we're also showing Montreal is a city at work and we're improving the conditions of our city," said Montreal executive committee member Jim Beis.