There has been a move towards a criterion-based return to play in recent years, with 4 single-leg hop tests commonly used to assess functional performance. Despite their widespread integration, research indicates that relationships between ‘passing’ ‘hop test criteria and successful outcomes following rehabilitation are equivocal, and, therefore, require further investigation. This critical review includes key information to examine the evolution of these tests, their reliability, relationships with other constructs, and sensitivity to change over time. Recommendations for how measurement and administration of the tests can be improved are also discussed. The evidence presented in this review shows that hop tests display good reliability and are sensitive to change over time. However, the use of more than 2 hop tests does not appear to be necessary due to high collinearity and no greater sensitivity to detect abnormality. The inclusion of other hop tests in different planes may give greater information about the current function of the knee, particularly when measured over time using both relative and absolute measures of performance. It is recommended that the contralateral limb be tested prior to surgery for a more relevant benchmark for performance, and clinicians are strongly advised to measure movement quality, as hop distance alone appears to overestimate the recovery of the knee.

Context: Deficits in plyometric abilities are common following anterior cruciate ligament reconstruction (ACLR). Vertical rebound tasks may provide a targeted evaluation of knee function. Objective: Examine the utility of a vertical hop test to assess function following ACLR and establish factors associated with performance. Design: Cross-sectional Setting: Rehabilitation Participants: Soccer players with a history of ACLR (N = 73) and matched controls (N = 195) Main outcome measures: 10 second vertical hop test including measures of jump height, reactive strength index (RSI) and asymmetry. We also examined possible predictors of hop performance including single leg vertical drop jump (SLDVJ), isokinetic knee extension strength, and the international knee documentation committee questionnaire. Results: Significant between-limb differences were identified for the ACLR group only and asymmetry scores increased in those with a history of ACLR (P < 0.001) compared to controls. SLDVJ RSI and knee extension torque were significant predictors of 10 second hop height (R2 = 20.1%) and RSI (R2 = 47.1%). Conclusions: Vertical hop deficits are present following ACLR even after completing a comprehensive rehabilitation program. This may be due to reduced knee extension and reactive strength. Vertical hop tests warrant inclusion as part of return to sport test battery.

Davies, WT, Ryu, JH, Graham-Smith, P, Goodwin, JE, and Cleather, DJ. Stronger subjects select a movement pattern that may reduce anterior cruciate ligament loading during cutting. J Strength Cond Res 36(7): 1853-1859, 2022-Increased strength has been suggested to reduce the incidence of anterior cruciate ligament (ACL) injury as part of wider neuromuscular training programs; however, the mechanism of this is not clear. Cutting is a high-risk maneuver for ACL injury, but limited research exists as to how strength affects sagittal plane biomechanics during this movement. Sixteen subjects were split into a stronger and weaker group based on their relative peak isometric strength in a unilateral squat (stronger: 29.0 6 3.4 N•kg 21 and weaker: 18.3 6 4.1 N•kg 21 ). Subjects performed 45˚cuts with maximal intent 3 times, at 3 different approach velocities (2, 4, and 6 m•s 21 ). Kinematics and ground reaction forces were collected using optical motion capture and a force platform. The stronger group had lower knee extensor moments, larger hip extensor moments, and a greater peak knee flexion angle than the weaker group (p , 0.05). There was a trend for greater knee flexion at initial contact in the stronger group. There were no differences in resultant ground reaction forces between groups. The stronger group relied more on the hip than the knee during cutting and reached greater knee flexion angles. This could decrease ACL loading by reducing the extensor moment required at the knee during weight acceptance. Similarly, the greater knee flexion angle during weight acceptance is likely to be protective of the ACL.

Few evidence-based guides exist to support coaches in delivering technical elements of cutting that may reduce the risk of anterior cruciate ligament (ACL) rupture. In isolation, balance exercises, jump landing, cutting movements, as well as modifying the penultimate step, may alter biomechanics favorably during this maneuver. By breaking this serial skill into its constituent parts, the coach is afforded an opportunity to observe trainable deficits, and allows the player more opportunity for practice. In addition, factors such as specificity to the direction of load during landings, alongside building capacity, and using externally focused cues may be crucial for adaptation and transference into open sporting scenarios.