Comparison of eccentric hamstring strength and asymmetry at return-to-sport after hamstring strain injury among those who did and did not re-injure

Objectives: The primary aim of this study was to describe eccentric hamstring strength magnitude and asymmetry at the time of return-to-sport (RTS) after an index hamstring strain injury (HSI) and deter-mine if there were differences in strength asymmetry at RTS between those who did and did not go on to re-injure within 1-month and within 3-months of RTS.Design: Cross-sectional study.Setting: Laboratory-based. Participants: Sixty National Collegiate Athletic Association Division I athletes with index HSI. Main Outcome Measures: Maximum hamstring eccentric strength for each limb, total maximum strength summed across limbs, and between-limb asymmetry at the time of RTS following the index HSI, assessed using the NordBord Hamstring Testing System.Results: Of the 60 index HSIs, 8 (13%), and 11 (18%) re-injuries occurred within 1 and 3-months of RTS, respectively. There were no differences between those who did and did not re-injure in maximum eccentric force of either limb (p-values >= 0.52), total force from both limbs (p-values >= 0.47), and between limb force asymmetry (p-values >= 0.91), regardless if re-injury occurred within 1 or 3-months after RTS.Conclusions: Eccentric hamstring strength and asymmetry measured at the time of RTS did not differ between those who did and did not re-injure within 3-months of RTS.(c) 2022 Elsevier Ltd. All rights reserved.