A US Navy vet did walking lunges for more 4.06 miles - breaking two world records in the process.

Mike McCastle, 38, completed his knee-crippling feat of endurance across Utah's Bonneville Salt Flats as part of a lifelong challenge to complete 12 extreme sporting missions.

He broke the world record for the most lunges in an hour - completing 3,262 - and the record for the longest distance travelled by walking lunges in the same time frame, covering 2.22miles.

And not content to just break two world records - he continued his walking lunges for as long as he could physically manage - a total of 20 hours and 39 minutes, finishing with 4,769 lunges over 4.06 miles.

He took breaks to use the bathroom, rest and eat - and because of lightning striking nearby.

The air traffic controller and performance coach from Las Vegas, says this is the first time anyone has done more than 12 hours of continuous walking lunges.

He prepared for the painful challenge with 12-16 hours of gym training over four to six days in a week for three and a half months.

And he fueled his mission with beef balls, rice and gels consisting of carbohydrates and protein.

He took on the challenge as the ninth in his self-invented '12 Labors Project' - a decade long mission to do 12 extreme physical feats.

It began after he found himself in "a really dark place" while recovering from multiple knee surgeries that ended his military career in 2016. "

Both knees were blown out during military training, leaving him without direction or purpose, he said.

"I perform these seemingly impossible physical feats of strength and endurance to raise awareness for charitable causes like Parkinson's disease research, veterans' mental health issues, and cancer," McCastle said. "

"These were things my late father suffered from and I have an intimate connection to."

"These challenges are just the vehicle for delivering a message behind the causes."

"I use these labors and the extreme nature of them to bring in that awareness and attention."

"It's okay that people call them extreme or crazy, and then they see that someone's able to do it and actually complete it."

He completed this challenge on October 11 during a 24 hour stint on the flats, and dedicated it to his son, Mikey, three, to teach him about perseverance.

A dedicated support team accompanied him, handling video recording, photography, nutrition, and caring for his son throughout the entire challenge.

In 2015, he rope climbed 29,000 feet in a gym - the height of Mount Everest - in 27 hours to raise awareness for Parkinson's disease.

The day after his father, Raymond, died in 2016 at age 76, he flipped a 250-pound tire for 13 miles straight.

That same year, he pulled a two-and-a-half-ton truck 22 miles across Death Valley to bring awareness to veterans' mental health issues.

In 2021, McCastle set the record for the longest full-body ice immersion, lasting two hours and 40 minutes, in a charity event live-streamed from Bethel, Alaska.

This was his ninth challenge - seven of which set or broke world records.

Speaking of what motivated him to start the 12-challenge mission, he said: "I was just lost, and I remembered back from when I was a kid, my father used to tell me these stories of the Greek gods and Hercules."

"I particularly remembered the 12 labors of Hercules, where he was made to endure these seemingly impossible labors in order to find redemption and purpose in his life."

He doesn't plan to rush his final three feats - and while he hasn't decided what the missions will be, he anticipated doing his next one two to five years time, so he can train.

"As I do these labors, and also as I get older, I do have to take more time and train more smart, he said."

"I have a son now also, so I also have to factor that into the challenges and labors that I take on."

For the cold-body ice submersion, the previous record was 2 hours and 35 minutes — he surpassed it with 2 hours and 40 minutes.

For pull-ups, he broke the previous record of 5,801 by completing 5,804.

When he pulled a truck for 20 miles, he set a new record for the longest distance a truck has been pulled within 24 hours, as there was no prior attempt.

The same was true for his rope climb and 13-mile tire flip — both were first-time records with no previous benchmarks.