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Context: The landing error scoring system (LESS) was developed to screen healthy individuals for anterior cruciate ligament  (ACL) injury risk factors using a jump landing task. The purpose of this study was to evaluate unique landing error components of a modified LESS scoring criteria to determine its clinical utility in patients following ACL reconstruction (ACLR). Design: An observational cross-sectional study design was implemented to determine if each individual error component of the modified LESS provided unique information in an ACLR patient population. Methods: Post-ACLR patients (N = 194 [47.9% female]) completed the LESS 7.91 (1.80) months after surgery. To complete the LESS, patients stood on a 30-cm plyometric box and jumped down to a ground target, at 50% of their height in front of the box, then completed a maximal vertical jump. The LESS was repeated 3 times. Two video cameras positioned 3 m from the landing area at a height of 1 m above the floor (frontal and sagittal) recorded all trials. Video analysis of landing kinematics was performed to determine scores for each error item using the modified LESS. Itemized error scores for each patient were evaluated using an exploratory factor analysis, and factors were retained if eigenvalues were greater than 1. Results: Our exploratory factor analysis yielded 2 factor groupings. The first factor (λ = 1.61) was comprised of 4 biplanar error items (ie, errors that occur in both the frontal and sagittal plane) that evaluated body segment positioning (eg, hip and knee flexion during landing). The second factor (λ = 1.02) was comprised of 2 errors occurring in the frontal plane that evaluated knee valgus and the overall impression of their landing strategy. Conclusions: Reducing the modified LESS errors to 6-items could improve the efficiency and clinical utilization of the LESS in ACLR patients. An abbreviated version of the modified LESS may guide clinicians’ decision making in gauging patients’ readiness to return to play after ACLR.

Context: Chronic ankle instability (CAI) is associated with altered gait mechanics and impaired sensorimotor function (eg, postural control). While corrective exercise programs are known to improve sensorimotor function in those with CAI, their impact on gait-related outcomes remains unclear. Design: A randomized controlled trial was conducted to investigate the effects of a corrective exercise program on gait kinetics and postural control in individuals with CAI. Methods: Seventy recreational and collegiate athletes with CAI (aged 18−35) completed the randomized controlled trial. Participants were recruited from the local sports community and randomly assigned to either a control group (n = 34) or an intervention group (n = 36). The intervention group participated in an 8-week National Academy of Sports Medicine (NASM) corrective exercise program, while the control group received no intervention. The NASM program targets muscle relaxation, lengthening, and activation, and finally, integration into functional movements. Gait kinetics, such as contact time, foot progression angle, and peak plantar forces, as well as postural control, were assessed at baseline and postintervention and submitted to 2-way repeated-measure analysis of variance to evaluate the effects of the intervention. Results: Significant interaction effects were observed for postural control (P < .01) and gait contact time (P = .001), indicating greater improvements in the NASM group compared to the control group. No significant group or interaction effects were observed for specific plantar force distribution regions or other gait outcomes (P > .05). Conclusion: The findings suggest that an 8-week NASM corrective exercise program improves postural control but has limited effects on gait kinetics in individuals with CAI.

Objective : Confirm the validity of low-cost home pulse oximetry (POx) for determining arterial occlusion pressure (AOP) and compare blood flow (BF) responses to externally applied pressures. Design : Cross-sectional study. Methods : Forty-two subjects were recruited. AOP was registered with POx and a high-resolution Doppler ultrasound. Peak (anterograde peak blood flow velocity and retrograde peak blood flow velocity) and mean blood velocity and BF were assessed in 5 different externally applied pressures: 0%, 25%, 50%, 75%, and 90% of AOP in upper and lower limbs. Results : Significant differences between POx and Doppler ultrasound were found (P < .001) in upper and lower limbs. In addition, the ability to identify AOP with POx was poor in both limbs (receiver operating characteristic curve: 0.644 and 0.477 in the upper and lower limbs, respectively). Moreover, BF in the upper limb decreased significantly in all conditions except 0% AOP (nonrestriction; P < .012); however, in the lower limb, BF decreased only in the 90% and 75% AOP condition (P = .010) compared with 0% AOP condition (P < .001). Thus, BF decreases in a nonlinear manner under relative externally applied pressures. Mean blood velocity decreased significantly in all conditions compared with 0% AOP (P < .05) in the upper limb, but in the lower limb, mean blood velocity was higher in the 90% AOP condition than in the 25% AOP condition (P = .008). Conclusions : The results suggest that a low-cost home POx is not a useful device for estimating AOP. Furthermore, BF does not decrease linearly with the application of relative external pressure in the upper and lower limbs.

Context: Side-to-side differences of lower limb range of motion and motor performance may predispose athletes to injury. Previous research has investigated side-to-side asymmetries among adult soccer players, but there is limited evidence for youth players particularly during preseason. The purpose of this study was to perform preseason side-to-side symmetry analyses using the anterior reach test, hip active internal (IR)/external rotation (ER), active knee extension (AKE), weight-bearing lunge test (WBLT), drop hop (DH), and single hop for distance. Design: Cross-sectional study. Methods: Sixty-nine male elite soccer players (age: 16.8 [0.9] y, height: 176.0 [6.8] cm, mass: 67.9 [6.4] kg) participated in the study. The anterior reach test, IR/ER, AKE, WBLT, DH, and single hop for distance tests were performed the first day of the preseason. The analysis included side-to-side group- (Bonferroni-corrected significance tests, effect sizes [Wilcoxon r]) and individual-level comparisons (absolute asymmetry [as percentage]). Limb symmetry indices were calculated and clinically significant absolute asymmetry defined (>10%). Clinically significant absolute asymmetry overall prevalence (as percentage) and side prevalence (as percentage) was computed for each measure. Results: Side-to-side significant differences existed for hip IR (P = .005, Wilcoxon r = .40). The overall prevalence of clinically significant absolute asymmetries for anterior reach test, hip IR, hip ER, AKE, WBLT, DH, and single hop for distance was 20.3%, 66.7%, 37.7%, 71.0%, 39.1%, 36.2%, and 5.8%, respectively. Conclusions: Group-level analysis found statistically significant side-to-side differences in hip IR only. Individual-level analysis revealed many players had clinically significant asymmetries in hip IR, hip ER, AKE, WBLT, and DH reactive strength index.

Context: People with a history of anterior cruciate ligament reconstruction (ACLR) often have continued impairments, limitations, and restrictions after completion of formal rehabilitation. Clinician-based outcomes (CBOs) and patient-based outcomes are measures that can be used to determine patient status. However, the test-retest reliability of these measures in people with a history of ACLR should be determined. Design: A repeated-measures, test–retest reliability design. Methods: Participants (5.3 [2.7] y since ACLR) reported to the lab on 2 separate testing occasions separated by 1 week. Participants completed all PROs followed by all CBOs. All assessments were randomized between participants to avoid an order effect. Intraclass correlation coefficients, minimal detectable change, and standard error of measure were calculated for each outcome. Results: All PROs and CBOs had clinically acceptable reliability except the Knee Injury Osteoarthritis Outcome Score-Activities of Daily Living (intraclass correlation coefficients  = .43), Knee Self-Efficacy Scale-Sport (intraclass correlation coefficients  = .46), and Balance Error Scoring System eyes closed (firm and foam), which demonstrated poor reliability. Conclusion: Commonly utilized PROs and CBOs to measure treatment effectiveness acutely after ACLR and throughout rehabilitation had acceptable test–retest reliability. These measures should be used to determine the effectiveness of targeted intervention strategies to improve lingering impairments, limitations, and restrictions in people with a history of ACLR.

Context: Hip muscle function has been reported to be altered in individuals with chronic ankle instability (CAI). The purpose of this study was to determine whether the single-leg squat test (SLST) could be used to detect differences in proximal muscle activation between individuals with and without CAI and to determine if there were differences in strength of the hip lateral rotators, extensors, and abductors between individuals with and without CAI. Design: A case-control study design was used to compare hip muscle activation and strength during the SLST between individuals with CAI, lateral ankle sprain copers, and healthy controls. Methods: Forty-eight participants (14 males, 34 females; median age = 22.00 y) participated in this study. Participants were separated into CAI (n = 18), coper (n = 15), and control (n = 15) groups based on published criteria. Surface electromyography was used to measure muscle activation of the gluteus maximus and gluteus medius during the SLST. Strength of the hip lateral rotators, extensors, and abductors was measured using handheld dynamometry and quantified using maximum isometric body weight normalized torque. Results: The CAI group utilized significantly more gluteus maximus muscle activation during the SLST than both the coper (P < .001) and control (P < .001) groups. The CAI group had weaker hip lateral rotators when compared with the coper (P = .001) and control (P < .001) groups, and weaker hip extensors strength when compared with the control group (P < .001). Conclusion: The results support existing literature demonstrating that there are proximal neuromuscular changes in individuals with CAI and suggest that the SLST has potential for use as a clinical measure of gluteus maximus activation in individuals with CAI. Further study is needed to determine whether the differences in activation are clinically detectable.

Context: Running-related injuries are a major barrier to running, depriving individuals of health benefits. Harmful running biomechanics like decreased knee flexion, increased loading, and excessive hip adduction can be positively altered by increasing step rate (SR). Increasing SR is typically accomplished with a metronome, but music may be a more enjoyable alternative for patients. Therefore, the objective was to compare the effects of music tempo and metronome cueing on running SR, peak positive tibial acceleration, peak hip adduction, and peak knee flexion during stance phase in healthy runners. Design: Controlled laboratory study. Methods: Forty individuals assigned to either music or metronome auditory cues completed a pretest running assessment wearing inertial measurement units while SR and biomechanical variables (tibial acceleration, peak stance phase hip adduction, and knee flexion) were collected. Auditory cues (music vs metronome) were set to the target SR of +5% above preferred. Participants began running at the same speed used during the pretest while increasing their SR. Auditory cues were then removed. Participants were instructed to continue running at the target SR while posttest data were collected in the same manner as the pretest. A 2 × 2 multivariate repeated-measures analysis of variance was used to compare SR and running biomechanical variables. Results: Both music and metronome groups increased SR between the pretest and posttest (P = .001). No differences were found in peak positive tibial acceleration, peak knee flexion during stance phase, and peak hip adduction during stance phase between the 2 conditions or timepoints. Conclusion: Both a metronome and music can be used to increase SR during running. Future research should investigate the long-term effects of music in gait retraining and increase SR to a magnitude that accompanies protective biomechanics. Clinicians may now offer a choice of music or metronome auditory cueing to better cater to psychological needs of runners.

Clinical Scenario: Knee-extensor strength training is commonly used in patients with knee osteoarthritis (KOA) to improve muscle function, mobility, and quality of life. For typical complaints that result in significant movement limitation or even immobilization, unilateral knee-extensor strength training of the unaffected or less affected limb to induce a cross-education (CE) effect in the contralateral affected limb may be a possible but understudied treatment option. Focused Clinical Question: Does unilateral knee-extensor strength training lead to CE effects in the contralateral affected limb in patients with KOA? Summary of Key Findings: Results from 2 randomized controlled/clinical trials (level 1b) and 1 quasi-experimental study (level 2) provided limited grade B evidence for the CE effect of unilateral knee-extensor strength training to improve maximal knee-extensor strength of the affected limb in patients with KOA. Clinical Bottom Line: Based on the current literature, unilateral knee-extensor strength training induces a significant CE effect in the contralateral affected limb by increasing maximal knee-extensor muscle strength in patients with KOA, but there is no consensus on the exact nature of the adaptations and whether different types of muscle contractions during training are superior to each other. Strength of Recommendation: Due to limited evidence (grade B), the true CE effect of unilateral knee-extensor strength training of the unaffected or less affected limb to improve maximal knee-extensor strength of the contralateral affected limb in patients with KOA remains unclear and needs further investigation.