I think it might be flexing. First you tense, which is the flex, then you relax.
A cast is placed on a fracture to immobilize the bone
"safe, because it stretches the muscle and joint without causing pain"
It triggers the brain to be able to feel the proper way to move
The best time iswhen you are sitting down, calm, for at least five minutes, and have not done any physical activity for around 30 minutes.
