Beyond peak torque: Longitudinal analysis of angle-specific isokinetic knee torques in collegiate athletes post-ACLR.

OBJECTIVES: To investigate changes in angle-specific knee extensor torque between limbs from 4 to 12 months post-anterior cruciate ligament reconstruction(ACLR) in Division I collegiate athletes at two different isokinetic velocities. DESIGN: Case-series study. SETTING: Laboratory-based. PARTICIPANTS: Isokinetic knee flexion and extension assessments of 17 athletes (11 female) at 4, 8, and 12 months after ACLR with bone-patellar tendon-bone autograft were evaluated. MAIN OUTCOME MEASURES: Angle-specific curve analyses were performed using statistical parametric mapping for torque data obtained between 14 and 101° at 60°/s and 240°/s velocities. RESULTS: At 60°/s, knee extensor torque of the operated limb increased between 4 and 8 months (18-101°,p < 0.001), 4 and 12 months (28-101°,p < 0.001), and 8 and 12 months post-surgery (62-70°,p = 0.002, and 79-90°,p < 0.001). Knee extensor torque was lower in the operated limb compared to the non-operated limb at 4 (47-97°,p < 0.001) and 8 months (65-90°,p < 0.001) for 60°/s, at 4 (21-89°,p < 0.001) and 8 months (50-77°,p < 0.001) for 240°/s, with no between-limb differences at 12 months post-ACLR for both velocities. CONCLUSIONS: Operated limb knee extensor torque increased throughout the majority of knee range of motion from 4 to 12 months post-ACLR at both isokinetic velocities, while non-operated limb torque only improved through a reduced arc of motion in greater knee flexion angles.

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 determine 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.