Allowing the rehabilitation of acute hamstring strain injuries (HSIs) to be guided by the pain threshold did not reduce the time to return to play (RTP).
However, it did lead to a greater recovery of isometric knee flexion strength and improved biceps femoris long head fascicle length at the 2-month follow-up.
Thus, applying early eccentric loading and long-length exercises to the pain threshold may help manage deficits in knee flexor strength and help maintain gains in biceps femoris fascicle length without influencing the RTP timing.
Since only two reinjuries occurred during the follow-up period, no conclusions can be drawn about differences in RTP safety between both approaches.
Nevertheless, the study’s findings provide support to the notion that the frequently used approach of making HIS rehabilitation pain-free is not necessarily based on evidence.
> From: Hickey et al., J Orthop Sport Phys Ther 50 (2020) 91-103 (Epub ahead of print). All rights reserved to Journal of Orthopaedic & Sports Physical Therapy. Click here for the online summary.
Recommendations are frequently made, that early exercises for HIS rehabilitation must be pain-free to improve safety and ensure timely RTP.
Nevertheless, this randomised controlled trial shows that not only there is no difference in RTP time when performing exercises to the pain threshold, but also that the latter approach may indeed bring prolonged benefits in terms of muscle strength and architecture.
From another perspective, this study also shows another way in which pain may not be strictly associated with structural damage.