(Patrick McDermott / Getty Images) (Patrick McDermott / Getty Images)

Every once in a while, an older teammate – and almost all of them are older – will see Anthony Rendon and laugh. The 22-year-old can pick up a bat and start swinging with hardly any warm-up.

“When I’m moving around or I’m in the cage, they’ll be like, ‘I remember when I could go in there and swing and didn’t have to stretch,’ ” Rendon said. “I got little comments like that, letting me know that I guess I am refreshed. I get made fun of a lot.”

When this year began, Rendon did not know how refreshed he would feel in mid-August. Rendon, the Nationals’ rookie second baseman, has already played more baseball this year than any other season of his career. Between the majors and minors, Rendon has played 98 games this season, more than he had played in college or last year in his first, injury-plagued season as a pro.

Last year, Rendon broke his left ankle in the second game of the season at Class A Potomac and appeared in only 43 games during the season, plus another 22 in the Arizona Fall League. In 2011, Rendon played 63 games at Rice, 55 of those as a DH because of a strained shoulder muscle.

“I just try to get in a routine,” Rendon said. “That’s what everybody was harping on last year when I working back from my injury down in Florida. All the coaches were saying, ‘You got to get a routine. It’s a long season compared to what you’re used to, especially in college.’ I stuck with my routine, and I feel good. Obviously not 100 percent, but I don’t think anybody is at this point of the season. I feel good. I thought I’d feel a lot more deteriorated.”

Rendon lifts weights prior to games and eats more calories than usual to keep weight on. After games, he sits in a hot tub and a cold tub to keep his muscles fresh.

The most important part of his routine may be the work he does on his ankles. At the end of the 2009 college season, Rendon tore ligaments in his right ankle, which required surgery to repair, and then re-injured the ankle when playing for Team USA. Rendon broke his left ankle last year. Now, he stretches his ankles and does calf raises to strengthen them.

“It’s something that’s going to be with me for the rest of my life,” Rendon said. “I’ve got to deal with it.”

So far, Rendon has responded well to the unprecedented burden. Rendon slumped through July as pitchers adjusted to him, throwing fewer fastballs inside and more offspeed pitches away. But he has recently adjusted back, going 8 for his last 26 with two homers and a double.

“It’s not so much physical,” Manager Davey Johnson said. “He’s in pretty good shape physically. It’s more the mental grind. But he went through that period where he struggled a bit, and his at-bats have been more quality at-bats.”

Johnson said he may give Rendon days off when a day game follows a night game. Otherwise, “he’s my second baseman,” Johnson said.

Rendon senses the physical toll – “my body knows,” he said – but he feels ready for the final quarter of the season. In the winter, to prepare for a long season, Rendon worked out under Houston-based trainer Ben Fairchild, a former college football player. Fairchild told him to prepare for a long year.

“Going through this now, I’m like, ‘He had a point,’ ” Rendon said.