Exercise helps recovery because it strengthens what?

Interesting video, below, by one of my favorite neuroscientists, Dale Corbett.  For the record: There is no one I know up doing a better job of translating what neuroscientists have to offer to stroke recovery. Have a watch. The insights really start at 1:40 in. I'll post my critique below the video.  

The overall message is important. Exercise is essential. It is unfortunate that the message is sort of convoluted in this video. They're talking first about TIA, and how if you have a TIA you should use exercise as a way to lessen the chance of a full-blown stroke. Then the discussion takes an obtuse tangent into how exercise is important to recovery, and then with no real explanation doubles back to talking about TIA again. Still, while maybe the messages should have been separated, both are important. 

1:50 Another person, besides Corbett, whose interviewed in this video is William Mcillroy, who like Corbett is a PhD. I quibble a bit with Mcillroy's statement that exercise can be started "...as short as two weeks after stroke." Charitably, this is highly debatable. Once a patient is medically stable, intensity should be increased to tolerance. There is no one-size-fits-all timeline for every survivor that is rigid enough to predict that someone can start exercise "as short as two weeks after stroke." In fact, it could be much shorter. For instance, in a survivor who is medically stable day 4, waiting another 10 days to start a progressively rigorous exercise program would allow learned nonuse to take hold. 

2:20 Both PhD's talk about how exercise is good for the brain. Corbett talks about how exercise helps cognition, and points out exercise also helps sensory motor recovery. I would remind anyone who is willing to listen: sensation and motor behavior are cognitive. We learn sensation and movement the same way we learn French, or trumpet, or algebra. That is, changes in motor and sensory behavior happen involve the same brain processes as any other kind of learning.

2:50 I'm not sure that there should be such an unequivocal endorsement of balance retraining using biofeedback. Certainly the research is not there yet. 

Having said all that, I think this is a really great video with some really essential points. Interviews can be misrepresented because the person being interviewed is not doing the editing. The points these guys were making may have been a ton more cogent in the original interviews. 

The best line is by Dr. Corbett: 

 "It's still early days and you know we're nowhere near to the level that I think we can get to. And if we can understand what the mechanisms are then we might be able to optimally better design exercise programs to improve stroke recovery." 

"Until then, anyone trying to sell you certainty is after your wallet," he didn't add.