PITTSBURGH -- Penguins star Sidney Crosby is optimistic about returning fully healthy for next season, but acknowledges he recently had a setback in his recovery from a concussion.

Crosby, who didn’t play this season after Jan. 5, stopped skating with his teammates during off-day practices and morning skates midway through the Penguins’ seven-game playoff series loss to Tampa Bay because he began experiencing concussion-related symptoms.

Previously, Crosby said those included headaches that made it impossible to take part in any physical activity.

Crosby still has not resumed working out and intends to remain sidelined for an indefinite period.

"I was working out and skating, but had a little bit of symptoms so I had to take a step back," Crosby said Friday, two days after the Penguins' season ended. "All the stuff that comes with it. Up to that point the progression had gone pretty well, but at the same time I still wasn't ready.

"(It's) frustrating. My expectation was that I wouldn't play, but I was trying to make sure that if there was any chance and it was possible to come back, that I was ready and did everything I could to be ready for that. It's frustrating and disappointing. You can't really control any of that. All I can control is what I was doing off the ice and trying to rehab. Unfortunately it didn't work out."

Crosby’s comments Friday reinforced those by Penguins coach Dan Bylsma throughout the playoffs that his captain was not close to returning. Crosby never was cleared for contact work during practice, a step he would have had to take before he could think about playing again.

Without the injured Crosby for the second half of the season, and forward Evgeni Malkin for much of that time following a season-ending knee injury, the Penguins were one of the NHL’s lowest-scoring teams. They were held to four goals while losing each of the final three games against the Tampa Bay Lightning -- including a 1-0 defeat Wednesday in Game 7 -- after opening a 3-1 series lead.

It was only the second time in franchise history the Penguins couldn’t hold a 3-1 series lead.