Most muscles have memory... So you stretch it and eventually it gets the Idea... You know - like working on getting that crotch to the floor while doing the splits...suffer enough - practice enough eventually it gets there. However, radiated muscles are damaged... Some beyond repair. Not necessarily saying you can't get it back but sometimes the lesson doesn't stick, so diligence is the key here. Wanna keep what you have? Do your exercises and do what you can to prevent worsening, and sometimes depending on the amount of damage and how much you pushed yourself while going through treatment and after you may never get back an acceptable range of motion. So someone whose muscles were In the direct path of the radiation, and who didn't chew, swallow, stretch, yawn and exercise during and after treatment, may not be able to regain the function lost, or see much improvement in comparison to someone did what they could despite the pain during treatment etc... Then again sometimes no matter what you do the damage is permanent, however continue to do what you can everyday even just to preserve whatever is left. also a reintroduction of blood flow to the area, (acupuncture) may help prevent further fibrosis. I think it very much depends on the person bent treated, and the qualifications of the person doing the treatment. I found it helped me maintain and improve my jaw muscles and neck muscles. But it doesn't work for everyone. Hugs.