I found this excerpt in an article about Ron Gronkowski at TheWildcard.com

Thought it was interesting.

'Once a player has been diagnosed with a concussion, there are five stages to clearing him for a return to action — a rest and recovery phase until any obvious concussion symptoms disappear, light aerobic exercise to make sure symptoms don’t return, strength training to again make sure symptoms don’t return, the ability to get through a full practice, and finally being cleared to participate in a game.

There’s no timetable for a player to get through those phases. Some can do it in less than a week, others require months. It all depends on the severity of the concussion.'

Patriots release new details on Gronkowski's injury - The Wildcard

This appears to have parts of the Buffalo Protocol.