It's a task so difficult it is hard to believe it is even possible: run seven marathons in seven days on seven different continents. But San Francisco tech consultant Chris Edell is living, breathing proof that it can be done.

Edell recently completed the World Marathon Challenge — an elite physical test that pushes competitors to their physical limits. Edell and a few dozen others chartered private international flights to hop between continents in a week, starting their journey with a marathon through the snow in Antarctica. 

"This plane didn't have any windows, and it was really janky inside," Edell recalled. "I mean you almost were kind of wondering, like, is this plane going to actually make it down there? But we ended up landing, and I just remember the moment that the doors opened, and we stepped outside. The sun was so bright that we had to wear sunglasses because of the sun reflecting off the snow"

After the race in Antarctica, the group traveled to Australia, South Africa, the U.A.E, Spain, Brazil, and ended the week-long journey in Miami, each time running a full marathon with very little rest in between.

"The hard part was managing nutrition, recovery, just getting from place to place. And over the course of the races a number of racers got injured so there were wheelchairs and various support staff helping us and medics," Edell said.

Edell spent a year training by running on the streets of San Francisco. He'd sometimes run in the dark or in the rain to simulate the kinds of conditions he might find during the global challenge, though nothing prepared him for running in the heat and humidity in Fortaleza, Brazil.

On top of his training, Edell juggled his work responsibilities and parenting a 2-year-old and 6-year-old with his wife, who he said was instrumental in making his goal of completing the races happen.

"I'd prepare for a 20-mile run, I'd be right out the door on mile 1, and I'd receive a call from daycare saying, 'Hey, your son's sick. You need to pick him up.' So, times like that made it pretty challenging overall."

If the physical challenge wasn't enough, just registering for the race is a feat alone. According to its website, the World Marathon Challenge costs $48,000 dollars to sign up for. Some elect for sponsors to help them fundraise for various causes, and others like Edell save their own money to partake.

As for his background as an athlete, Edell said he didn't consider himself to be a lifelong elite runner, but said this challenge presented a unique opportunity to push his mind and body to the limits.

After a week of back-to-back races, flights, and limited time to recover, Edell ran more than 183 miles and completed the mission.

"There was a feeling of immense physical pain. But on top of that, there was this sense of almost peace where I realized this experience may never happen again, so I almost felt like I was in a dream the last 3 miles running by myself toward the finish line."