Ravens cornerback Lardarius Webb failed his conditioning test Wednesday, which kept him off the practice field as training camp began Thursday in Owings Mills and earned him a spot on the non-football injury list until he passes.
"The conditioning test measures anaerobic conditioning," coach John Harbaugh said. "It measures the ability to recover, to get your heart rate up and recover. Webby is in really good shape in a lot of different ways, I can see it in the way he moves in the weight room, but he's not in the kind of anaerobic shape he needs to be in to come out here and practice."
Harbaugh said the test is part of the physical examination the team conducts to prevent an injury caused by fatigue.
"The idea [is] that if I go play after play after play and I begin to get fatigued, I can't move the way I need to move," Harbaugh said. "I'm going to have a fatigue type of injury. That's why it's part of the physical, and that's why we don't allow guys to practice until they're anaerobically in condition."
Webb took the result hard, Harbaugh said. He was "disappointed he didn't make it," and "will be very determined to make it through," the coach said.
"It's always a big deal," Harbaugh said. "It was a big deal when Jacoby [Jones] didn't pass it [in 2013]. It was a big deal when Haloti [Ngata] didn't pass it [in 2012]. It's always a big deal. You want to see guys pass it."
However long he's out, Thursday marked the beginning of Webb's second straight limited training camp. He felt the effects of a back injury that lingered through September on the opening day of training camp last year, and needed until midseason to regain his form.
He restructured his contract in the offseason to lower his salary cap figure from $12 million to $9.25 million, with a lower base salary that has playing time incentives that could bring him back to his previous level.
Casey Walker, who is dealing with knee tendinitis, was also absent Thursday and was placed on the physically unable to perform list. Safety Terrence Brooks (knee) and tight end Dennis Pitta (hip) were placed on the PUP list last week.
Baltimore Sun reporter Aaron Wilson contributed to this article.