"Running is so primitive," he said. "It's like the simplest form of movement, and we were designed to do that."

Extreme athletes can be found across the military, which is a career field that can appeal to these athletes. Some service members also find that preparing for competitive events can dovetail well with other military training programs.

"Due to the extreme nature of their career and previous experiences in combat deployments, many service members enjoy high-risk, challenging and thrilling activities," said Nicole Leth, a certified personal trainer, health educator, and director of the Armed Forces Wellness Center in Ft. Belvoir, Virginia.

"Training for these events brings structure to workouts."

Getting there is a balancing act

Training for ultra-events like these takes extreme dedication, discipline, commitment, and proper training - which includes incremental training, rest, recovery, and proper nutrition.

It also carries risks, like overtraining, misguided supplement use, burnout, malnutrition, and overuse injuries, Leth said.

Most injuries are due to overuse. "Mostly tendinitis, joint pain, and stress fractures," Leth said. "I would also say mental fatigue and reported poor mental health."

That's why it's key to follow a research-based training plan from an experienced coach that includes rest and recovery.

"Programming rest and recovery days into your regimen will reduce symptoms of overtraining and allow muscles to rebuild as long as proper nutrition is in place," said Navy Lt. Sarah Alferos, a physical therapist with the Physical Therapy/Sports Medicine and Rehabilitation Team at Navy Medicine Readiness and Training Command Pearl Harbor in Hawaii.

Athletes can find training support through the Military Health System.

"The Wellness Center staff are able to guide service members to reputable, evidence-based resources for training and would cover healthy exercise, eating habits, sleep and stress management in accordance with the individuals' needs along with performance fueling information," said Leth.

Registered dietitians at military medical treatment facilities can offer dietary guidelines for training and performance fueling.

Proper gear, like wearing the right shoes, bringing a headlamp or reflective vest for oncoming traffic, and proper hydration and nutrition, is also key. Whether you have a support crew ensuring you have these along the course or carry them with you in a fuel belt or pack, experts recommend training over time with everything you will wear and consume on race day to avoid surprises.

"Every company creates different types of shoes depending on your foot type, whether you need a neutral shoe due to a high arch, or a stability shoe due to low arches," said Alferos. "Visit a local shoe store and have them identify your arch type and toe box preference, assess your running form, and recommend an individual shoe for your foot."

Zitta appreciates having access to proper care through his primary care manger. He also has a coach who "keeps him in check." And over his years of ultra-endurance events, Zitta has only suffered one injury that set him back.

"It was a stress fracture just below my knee and my tibia," due to "just ramping up the training too quick one year. But I have been really fortunate to remain healthy over the last decade of competing."

To prepare, he explained he tailors his life around every specific event, not only in terms of training but also nutrition and balancing his time between work and family.

"Everything shifts in preparation for that specific event," he said. "If it's a running event, then obviously all my training will be primarily focused on running, and as training intensity ramps up, then so does the intensity of my kitchen prep - food is very important."

In general, the lessons learned over the years have allowed him to "become really good at balancing the time it takes for me to invest in events of this nature," he said. "But now, my time with my family is more important to me than any event ever could be."

Over the years, Zitta has grown to enjoy the comradery among the other athletes who compete in these elite events.

"The endurance community is extremely special," he said. "Whether you're doing Ironmans, or ultra-marathons, or ultra-swims, the people are all so genuine and welcoming, and generally pretty happy, so I've learned a lot from the people in these communities."

He believes the human body is a tool that is never used to its full potential. "But there is something special with endurance athletes, somehow, through time, they're able to train their minds to go further."

"Once people work on being in tune with themselves, in their mind and their body, the possibilities are endless."

"I mean, people are running 240-mile races now with no sleep," he said. "So, to me, that indicates that the potential for the human body and the human brain are far beyond what a lot of people realize."