Bill Sikes/Associated Press

New England Patriots tight end Rob Gronkowski said he is "100 percent" recovered from back surgery when speaking with reporters Tuesday at organized team activities.

“No, definitely no doubts,” Gronkowski said. “I just know that all the hard work you put in is what you’re going to get out of it. I love to put in the work. [I] love the challenge sometimes. It is what it was and now I’m good to go.”

Gronkowski, 28, was limited to eight games—starting six—due to myriad injuries in 2016. He missed time with a hamstring injury and pulmonary contusion before undergoing surgery for a herniated disk in his back. It was Gronkowski's third surgery on his back and ninth overall since 2009.

Gronkowski participated in OTAs Tuesday and said doctors have placed no restrictions on him.

"Just being able to compete, conditioning-wise, strength-wise, in the weight room, being out on the field with teammates, being able to play football, it's great," Gronkowski told reporters. "It's always important to me, whenever I get a little setback like that, to get back to where I need to be. I feel like I am—doing everything out here, competing. It's fun."

80 receptions, 1,200 yards or be named to the All-Pro team. The Patriots nevertheless restructured Gronkowski's contract last month, with performance-based incentives that could make him the highest-paid tight end in football. He could make as much as $10.75 million in 2017, should he play 90 percent of plays or record