EXCLUSIVE: 'Grey's Anatomy' Stars Compete in Tough Mudder for Homeless Youth, Talk 'Juicy' Upcoming Episodes

It was Sunday, muddy Sunday.

It was Sunday, muddy Sunday as the spunky doctors of Grey’s Anatomy took a break from the operating room to trudge through five miles of mud in the scorching California heat over the weekend.

Cast members Giacomo Gianniotti (Dr. Andrew DeLuca) and Martin Henderson (Dr. Nathan Riggs) surrendered themselves to mud, dust and dirt while completing the Tough Mudder Half, an obstacle course fraught with arduous hurdles and physical challenges, yet somewhat easier than learning surgical procedures.

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"It's definitely easier fighting through mud," Giacomo, 26, told ET with a laugh at the finish line. "Surgical procedures are hard to learn, for sure."

"There are too many things to remember -- the name of the instrument, how to tie off the suture," agreed Martin, 41, who sped through a course that usually takes two-three hours in under 90 minutes. "You don’t need to remember anything when you run in the mud!"

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The pair were part of Grey’s Anatomy’s 41-strong Mudder Squad, who endured several miles of mud-drenched obstacles, while helping raise money for Hollywood non-profit My Friend’s Place, which assists Los Angeles' homeless youth.

Tough Mudder

Both actors, who did not grow up in Hollywood, recalled being astounded by the high level of homelessness when they first moved to LA. After becoming an ambassador for My Friend’s Place, Giacomo launched a fundraising campaign in conjunction with the mud run, helping to raise over $15,000 for the organization’s Transformative Education Program.

The actors agreed that an unforgiving steep and never-ending hill proved the biggest challenge of the San Bernardino course. Actress Camilla Luddington (Dr. Jo Wilson), who represented the ladies of Grey’s, credited Giacomo and Joe Adler (Dr. Isaac Cross) for helping her conquer the punishing ascent.

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“I’ve never done a run like this, so it was incredibly intimidating,” said the 32-year-old actress, who ran alongside friend and Strong contestant, Jasmine Loveless. "I thought there was no way I was going to get through it, but Giacomo and Joe literally helped me up every single part. Right at the end, I face-planted and hurt my knee, but was fine until that last moment!"

Tough Mudder

Joe also assisted elderly female contestants who were “killing it," while Jason George (Dr. Ben Warren) crossed the finish line more than an hour after his cast mates, having completed each obstacle up to three times, while motivating lagging crew members who were on the verge of giving up.

“I’m a Navy brat from a big military town, so ‘never leave a man behind’ is a real thing,” Jason said. “That’s how my boys would roll growing up, even if we were getting in trouble, we had to go back, grab the slowest kid and get them to move their a** before we got caught doing whatever it was we weren’t supposed to be doing.”

He added, “So, I tried to help make sure everybody pushed themselves as far as they could go.”

As the group celebrated with beers, Jason admitted that a far greater obstacle course lies ahead, on-screen, as Grey’s picks up from last week’s action-packed two-hour special. The episode saw Ben’s marriage hit the rocks after he performed an emergency cesarean, forcing his wife and boss, Dr. Miranda Bailey (Chandra Wilson), to suspend him.

Tough Mudder

“They’re rolling in some mud right now!” he shared. “It’s going to be hard because she’s lost faith and respect in him as a surgeon, and he’s lost faith and respect in her as a spouse.”

“It’s been fun to play, and has forced me and Chandra to go places we haven’t gone before,” Jason continued. “We always have a blast bickering. We do that off-camera, because I come in and start messing with her in the trailer and she gives as good as she gets all day long. But this has pushed us to a whole different place.”

Meanwhile, Giacomo and Martin teased that their characters’ love lives could also be heating up before the show wraps up season 12. Martin revealed Nathan will finally get some action, locking lips with one lucky lady in the coming episodes. "Things are getting juicy,” he teased, while Giacomo hinted at new liaisons for Andrew.

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“They’re throwing me into different people’s story lines now that DeLuca and [Dr.] Maggie Pierce (Kelly McCreary) have gone their separate ways,” he disclosed.

As for off-screen, Giacomo joked about his Valentine’s Day date with his co-star. “Martin had me over and said, ‘My neighbor's cooking dinner and asked me to bring dessert. Would you help me in making this kiwi [New Zealand] dish called pavlova?’” Giacomo recalled. “I was like, ‘Absolutely, no problem.’ We looked online for the best recipe, made it together and it was delicious.”

“Maybe now that he’s got me out in the mud, I’ll bake him a carrot cake,” Martin quipped.

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Check out the Grey's team's fundraising page here and enter for a chance to visit Giacomo on the set!