John Erskine knows he’ll need to fight for playing time and a regular spot in the lineup this year given the Capitals’ depth on defense, but what remains unclear is when he will be able to take full contact in practice as he continues to recover from shoulder surgery.

The 31-year-old defenseman injured his left shoulder last March (he missed three games at the time) and later underwent successful surgery to repair the joint in May, but the rehabilitation has limited Erskine’s offseason training and it’s uncertain if it will limit his participation at the start of training camp.

On the ice Tuesday morning at Kettler Capitals Iceplex, Erskine took part in workouts and a bag skate with the 14 other players who have returned to Washington, but at times it was apparent he wasn’t taking many shots or using his injured arm much.

“I’ve been doing a lot of one-armed stuff,” Erskine joked about his workouts this summer. “It was frustrating at the start, the first half of the summer, when I couldn’t do what I wanted to. When I first got on the ice I couldn’t really shoot the puck or anything like that, but things are getting better now. I’m getting the strength back but I’ll see the doctor later this week and go from there.”

Presumably, Erskine was one of the players General Manager George McPhee alluded to over the course of the offseason when he repeatedly mentioned that players in addition to Tom Poti, who missed all but 21 games last year with a nagging groin strain, may not be ready at the start of the 2011-12 season.

“I’ve been skating but I haven’t been doing a lot of intense skating,” Erskine said of his progress. “At home, I’ve been doing some of the two-on-two, three-on-three things. I felt good out there today, though. And I hit [D.J. King] a couple of times and it felt good.”

Excluding Poti, the Capitals will open training camp later this month with seven NHL defensemen under contract. Regardless of how much more time his shoulder needs to fully heal, Erskine acknowledged that despite having one of his most consistent outings in the 2010-11 season he’ll have to battle to avoid falling to that seventh spot on the depth chart.

“I don’t know if I will be six, seven or somewhere else but you’ve got to come into the year open-minded,” Erskine said. “It makes our team better to have that depth on defense whether in the season or into the playoffs. I just want to come into camp, play my hardest and see where it goes.”