Jim McAlpine, founder of Power Plant Fitness gym, said he hopes the center will help to dispel the image of the lazy stoner

From protein shakes to energy drinks, athletes have all sorts of substances they take both before and after workouts to boost their performance.

But one gym set to open in California is about to add another unlikely substance into the mix in the form of cannabis.

Power Plant Fitness, which is being planned for San Francisco, will even sell specialist pre-workout and post-workout edibles to help uses get their buzz and sweat on at the same time.

Founder Jim McAlpine, who also created stoned running event 420 Games, said the gym aims to improve people's fitness through the controlled use of cannabis while also dispelling the image of lazy potheads scoffing snacks.

In much the same way as a typical gym induction, McAlpine will give new users a 'cannabis performance assessment' when they join, Tech Insider reports.

This will work out how each member responds to working out while high, and discover the optimum amount and way to consume while in the gym.

Initially the center will allow vaping and edibles on site, but McAlpine said he plans to add a smoking deck for those who prefer more traditional methods of consumption.

McAlpine added that eventually Power Plant Fitness will introduce its own range of supplements designed to aid both workout and recovery.

Recreational cannabis use is still illegal in California, meaning that for the time being any gym members would also have to possess a medical marijuana card to make full use of the facilities.

McAlpine already runs 420 Games, a series of 4.2 miles runs around the US that encourages participants to compete while high (pictured)

While relatively little research has been done into the effects of cannabis on athletic ability, the World Anti-Doping Agency lists THC, the active ingredient in marijuana, among its banned substances - meaning they have reason to believe it could be beneficial in competition.

Anecdotal evidence suggests that many athletes find cannabis does improve their fitness, helping them to work out for longer with less pain, and recover quicker afterwards.

Ricky Williams, a former Heisman Trophy winner and NFL player, is currently spokesman for the 420 Games and openly discusses the benefits of cannabis combined with exercise.

Clifford Drusinsky, a triathlon competitor, told Men's Journal that he consumes a cannabis bar before each training session and notices it significantly improves his endurance.

While the medical benefits of cannabis and exercise are relatively unknown, athletes have reported anecdotally that the substance has helped them train and recover

He said: 'Marijuana relaxes me and allows me to go into a controlled, meditational place. When I get high, I train smarter and focus on form.'

Meanwhile Nicholas Edwards, an exercise physiologist at the University of Colorado School of Medicine, told US News that he has heard from hundreds of athletes with similar stories.