When Jim McAlpine first founded The 420 Games - perhaps the world's first series of athletic events expressly geared toward fitness-conscious marijuana users - many people were skeptical.

"Most people would just laugh at me as I explained my idea," McAlpine said in a press release. "The stigma runs deep and people immediately go to the propaganda engrained in their brain that says marijuana and athletics don't mix."

As the series of 4.20 mile runs in different cities heads into a second year, the number of participants has increased from 200 in 2014 to more than 10,000 in four states and six cities this year. The tour includes stops in California, Colorado, Oregon and Washington.

"We have followed the business models of big events such as Tough Mudder and Spartan Games," said event producer Jonn Hampton. "People are drawn to 'lifestyle events' which is precisely what The 420 Games athletic series is."

Encouraged by the success of the first 420 Games, McAlpine and Ricky Williams, a medical marijuana advocate and former NFL player, are opening the world's first cannabis gym in San Francisco this November.

At Power Plant Fitness, members will be able to consume cannabis in the gym while working out, as well as purchase a line of "athletic edibles" designed for pre-workout focus and post-workout recovery.

"It won't be a place to get high and just screw around," McAlpine says in a blog post on the 420 Games website. "We are focused on the athletic side, not the cannabis side."

Are you up for a 420 Games Event this year?

California

July 17, August 27: San Francisco, Golden Gate Park

Washington

July 31: Seattle, Magnuson Park

Colorado

September 17: Denver (location TBD)

October 1: Boulder Reservoir

Oregon

October 29: Portland, Sellwood Riverfront Park

For more information and to purchase tickets, visit their site.