The Redskins’ acknowledgement Friday night that an independent neurologist had concluded that quarterback Robert Griffin III should not be cleared to return competition, reversing a decision to clear him just 24 hours earlier, raised numerous questions.

Among them: How was Griffin cleared to practice last week, less than 72 hours after suffering the concussion-like symptoms in an Aug. 20 battering against Detroit?

Coach Jay Gruden explained last Sunday, when Griffin made his surprising return to practice, that the quarterback was back on the field because doctors had cleared him. “He just went through the necessary steps with the doctors and the concussion tests that is all implemented by our training staff,” Gruden said. “And so far, he has taken the necessary steps.”

Gruden was alluding to the NFL’s concussion protocol, a four-page document compiled by the NFL’s Head, Neck and Spine Committee, with input from the NFL Players Association, NFL Physicians Society and the Professional Football Athletic Trainers Society.

Given its length, it’s tricky to boil down. But it lays out five steps a concussed athlete must go through in order to be cleared to play. It states at the outset that no single timetable can be applied to all cases.

“Each player and each concussion is unique,” the protocol states. “Therefore, there is no set time-frame for return to participation or for the progression through the steps of the graduated exercise program set forth below. Recovery time will vary from player to player.”

In Griffin’s case, he sped through steps 1-4 in less than three days, which seemed implausible at the time but did not violate the NFL protocol because it doesn’t mandate a time frame before proceeding from one step to the next.

(In the case of young athletes, however, concussion protocols mandate at least 24 hours before progressing from one step to the next).

For those seeking a better understanding of what the NFL concussion protocol requires, here’s a look at its five steps:

Rest and recovery. Players may stretch and work on their balance, but they don’t work out beyond that. In addition, they’re advised against spending time on computers, any electronic device and social media. They don’t take part in team meetings.

Light aerobic exercise. Under supervision of the team’s medical staff, the player can start cardiovascular exercise, such as riding a stationary bike and using a treadmill, and work on more dynamic stretching and balancing. The workload is increased gradually and halted entirely if concussion-related symptoms recur. Players can attend team meetings and study film.

Continued aerobic exercise, introduction of strength training. Building gradually on the work of step 2, the player can start weight training.

Football-specific work. The player adds non-contact football drills, such as throwing, catching and running to his repertoire of exercise. No contact allowed with other players, tackling dummies or sleds.

Full football activity, full clearance. The player resumes practicing with the team, with no limitations. Once the team physician clears him to complete, the player is examined by the independent neurological consultant, who also reviews any relevant neurological tests.

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