GOLDEN — The tattoo is simple, just two plain letters — XC — but for Tyler Curtis and almost anyone who has run cross country, those letters are full of meaning. They symbolize a noble sport, a unique team bond, a time of year that feels and smells different — and one that creates lifelong memories.

Shorter, cooler days. Leaves turning and falling. Races on grass and dirt. Mud-splattered shins and soggy shoes. Running as a team sport rather than an individual pursuit.

That's why Curtis, a sophomore on the nationally ranked cross country team at Colorado School of Mines, had those two letters etched permanently on his back. That, and the sheer difficulty of racing over hill and dale, in heat or sleet.

"I just love pushing my boundaries," Curtis said last week after his team did one of its signature workouts, a run up Lookout Mountain. "I always like to challenge myself."

There is no bond quite like the one that unites a cross country team. No matter how good a team's best runners are, the team's fortunes often depend on how good its fifth-best runner is.

"There's no feeling like that camaraderie you have when you're putting in all that hard work, sweat and tears into your sport, together," said Mines coach Art Siemers, one of the top road racers in the Denver area. "There's also no other sport where the fifth man or woman is the most important."

A track team is a collection of specialized athletes training in specialized ways — throwers, sprinters, jumpers, distance runners — but everyone on a cross country team trains pretty much the same way and experiences the same pain.