The classic cross country runner’s build is rail thin ... the less bulk to carry during a grueling 5-mile race over unforgiving terrain.

Chris Affannato is the antithesis of the classic cross country runner. He has the steely determination and the unwavering work ethic, but that body was not made for distance running.

His being a distance runner seems as unlikely as Billy Ray Cyrus being named Father of the Year.

But the powerful 5-8, 180-pounder with the tree-trunk thighs is a cross country runner for the Massachusetts Maritime Academy. A tri-captain to boot.

“I’m still a lineman at heart,” said Haverhill’s Affannato.

Indeed, he was a starting offensive lineman for Whittier Tech’s unbeaten 2009 Eastern Mass. Division 4 Super Bowl championship team.

Affannato has only been running for the Buccaneers since last fall, but MMA coach Chris Ryan said the captain honor was “well deserved.”

He added, “Chris gives a total effort in every practice and race he enters. He is, as I have told him, our bulldog!”

That’s an apt and ironic description as the U.S. Marines’ mascot is the bulldog. Affannato is studying and training to be a Marine officer.

With the football physique comes the football mindset.

As Ryan put it, “He attacks the five miles like a football lineman attacking the quarterback.”

Just like cross country, the 5-8, 180-pound Affannato doesn’t have the ideal frame to be a college football lineman.

“I gave it (football) a little bit of though, but the military career came first,” he said from the training ship Kennedy, which was traveling through the Cape Cod Canal.

The military career always came first.

“I was six years old,” recalled Affannato, who just began his senior year at MMA. “My dad and I were watching the Discovery Channel’s ‘10 Most Deadly Jobs.’”

In high school he starred on the football team, competed in track (no races longer than 400 meters!), was class president, graduated in the top 10 overall in his class of 400 and spent his summers in the United States Naval Sea Cadet program.

He was nicknamed Sarge then and someday he probably will become a sergeant ... or higher.

Nonetheless, how could someone who’d been with the program little more than a year, and admittedly is no star, be named a captain?

His coach’s mindset is more:

How couldn’t he be one?

“Wow, does Chris give it his all,” began Ryan. “He is a young man of character. He is a motivator. He is a fabulous leader and teammate. He possesses an incredible work ethic. Every inch of the five miles he runs is run with passion and all-out effort. He leaves nothing out on the course. I couldn’t be more pleased with him serving as a captain.”

Leadership has always been as much a part of Affannato as the tree-trunk thighs, which are more suited to those Marine officer 12-mile training hikes with 50 pounds of equipment on his back.

“They know I’m there for them,” he explained. “I’ll make sure to take care of them. Being a leader is a natural thing. I can’t get away for it. I enjoy taking care of others and getting the job done.”

Those leadership traits, of course, should translate well to his military career. He’s platoon commander for the Seventh Command with 48 students under his watch. They’ve traveled the country performing at parades in New York City, Washington, D.C., and numerous smaller locales near and far.

This summer he spent six weeks at officer candidate school in Quantico, Va., to earn the right to commission as a Marine Corps officer.

After graduation from Mass. Maritime, which is located on Buzzards Bay on Cape Cod, he’ll attend Basic School at Quantico for six months to train to be an infantry platoon commander. Then 6-8 weeks at Military Occupational Specialty School. Then he’ll be sent to his first platoon.

The distance running came from training to get into peak shape. He could do 20 pull-ups and dead-lift 370 pounds but he wanted to improve his cardio.

“I just needed to train the legs,” he said. “All the running was mostly prepping for the military.”

In the spring of 2012, he and another future Marine, Matt Lincoff, bandied about the idea of trying out for the team.

“I was on the fence at first,” said Affannato.

Ryan welcomes walk-ons if they have the right attitude. One thing Affannato has is the right attitude.

He’s thrilled that he gave it a shot.

“It clears your mind. It’s awesome, you push yourself past what you can do,” said Affannato.

The former lineman/discus thrower, was anything but a natural.

“My first time was really bad, 35:30 (for 8 kilometers, which is almost exactly 5 miles),” he recalled. “I cut it down to 32:50. I’m hoping to crush that time this year. It’s a pretty good feeling passing these small anorexic-looking guys. I may not pass many, but its a good feeling.”