Injuries to the hamstrings can be career-threating and the rehabilitation process is crucial in the process for return to play. In times past, when completing rehabilitation for hamstring injuries, pain has been a leading factor on whether an exercise able to be completed.
Recently a study by Hickery et al 2019 that used pain free and pain threshold to commence rehabilitation exercises showed that the pain-threshold rehabilitation did not accelerate return to play clearance but did result in greater recovery of isometric knee flexor strength and better maintenance of biceps femoris long head fascicle length improvements compared to pain free rehabilitation.
So what does all this mean? The conventional clinical practice of pain avoidance during hamstring strain injury rehabilitation does not appear to be necessary.