Calgary's annual two-day Spartan Race drew twice as many participants compared to last year.

The giant obstacle course is held in countries around the world and sees roughly a million participants each year. In Calgary, there were 9,000 people registered for the event.

"It's nothing like anything else," said racer Louise Robinson. "All the other races and runs that you have in the city are just nice little trail runs or easy little things. This is the ultimate test of how strong you are."

Spartan is a new craze in racing.

Racers push themselves through more than a dozen obstacles including a tire toss, spear throw, rope courses and a mud pit.

They can choose from three race lengths — the Sprint is a five-kilometre run with 15 obstacles, the Super runs 13 kilometres with 21 obstacles and the Beast is a 20-kilometre haul with 26 obstacles.

All the courses are unique from one race to the next, which is one of the draws for competitors, say organizers.

"We're never the same," said Dean Stanton, one of the race organizers. "Each year we're always changing things up, we're always adding things, keeping it fresh."

But it's not only the racers getting an adrenaline rush. Organizers say they welcome people who come out just to watch take in the spectacle.

Spectator tickets were by donation only.

The Calgary race is a Sprint and took place Sunday at the Wild Rose Motocross Park.