Two teams of runners raced across the top of the mountain and into the Pretty River Valley as part of the 900 km trek for the Blaze Niagara Escarpment Race.

The two teams are made up of 10 runners each. The route of the race takes the runners from Tobermory to Niagara Falls. The Muscle Team is raising money for the Canadian Muscular Dystrophy Association. The Mitochondrial Team is raising money for the United Mitochondrial Foundation.

The runners on the teams run day and night to complete the distance.

Runner Mark Tarnpolsky said on Thursday that the day and night running and the rugged terrain made the trek a challenging adventure.

"It's very rocky in a few places. It's tough on the quads and it's tough on footing. We have seen two serious ankle injuries," said Tarnpolsky.

At night the runners wear high-powered lights on their heads to make sure they can see where they're going. Each runner always carries a cell phone and a First Aid kit in case on an injury.

"We're a bunch of people who love being outside and we love the Bruce Trail. All of us are current or former national level athletes. It's an interesting challenge," he said. "We're having a race to see who raises the most money," he added.

Some of the runners are scientists. Part of the event is a study looking at the affects the event will have on the bodies of the participants.

"We're looking at how the different variable influence muscle damage. We're looking at nutrition. We have a number of scientific and safety related questions," said Tarnpolsky.

During the race each runner runs a 12-26 km leg each day. There are 45 legs to the race. The athletes run a leg once every 18 hours.

The day and night running certainly creates challenges and unique experiences.

"I was running last night and saw two eyes in the woods. It didn't look like they were after me," said runner Jack Van Dorp, who was preparing to run a leg across the top of the mountain on Thursday afternoon - his second leg of the day.

Shortly after speaking to the newspaper Van Dorp was off on his leg. He participated in the official change over. Runner Jeff MacInnis handed him the First Aid kit and the race baton. MacInnis was in good spirits after finishing his leg.

"It hurt," he said. "This is probably the trail I run the most. It's no nice. It's beautiful. I don't think there is a better spot to run," said MacInnis, a local resident.