Differential influence of quadriceps rate of torque development on single- and double-leg landing mechanics in anterior cruciate ligament reconstructed and control females.

PURPOSE: The capacity to explosively contract quadriceps within the critical timeframe associated with anterior cruciate ligament (ACL) injury, quantified by the rate of torque development, is potentially essential for safe landing mechanics. This study aimed to investigate the influence of explosive quadriceps strength on ACL-related sagittal-plane landing mechanics in females with and without ACL reconstruction (ACLR). METHODS: Quadriceps explosive strength and landing mechanics were assessed in 19 ACLR and 19 control females during isometric contractions and double- and single-leg jump landings. A stepwise multiple linear regression model determined the variance in each of the landing biomechanics variables for the ACLR limb and nondominant limb of controls that could be explained by the group, rate of torque development and/or their interaction. If peak kinetic variables could be predicted by the rate of torque development or interaction, additional analyses were conducted, accounting for knee flexion as a covariate in the regression model. RESULTS: During single-leg landings, ACLR females exhibited greater knee flexion at initial contact than controls (p = 0.04). Greater quadriceps rate of torque development predicted higher peak posterior ground reaction force and anterior tibial shear force in both groups (p = 0.04). However, after controlling for knee flexion angle at those peak forces, quadriceps rate of torque development was not predictive. In double-leg landings, greater explosive quadriceps strength was associated with quicker attainment of peak knee extension moment and posterior ground reaction force in the ACLR limb (p = 0.03). CONCLUSION: Regardless of ACL injury status, females with greater explosive quadriceps strength adopted safer single-leg landings through increased knee flexion, potentially mitigating ACL loading despite encountering higher peak forces. During double-leg landings, a greater explosive quadriceps strength of the ACLR limb is associated with faster achievement of peak force upon landing. Incorporating explosive quadriceps strengthening into post-ACLR rehabilitation and injury prevention programmes may enhance landing mechanics for reducing primary and subsequent ACL injury risks. LEVEL OF EVIDENCE: Level II.

The Effects of Contralateral Trunk Tilt on Elbow Varus Torque in Baseball Pitchers: A Critically Appraised Topic.

Clinical Scenario: Ulnar collateral ligament injuries are common in baseball pitchers, with excessive elbow varus torque linked to medial elbow injuries. Trunk tilt, or motion in the frontal plane, could be an identifiable and modifiable factor in medial elbow loading. Clinical Question: In high school through professional baseball pitchers, how does increased contralateral trunk tilt compared with no/limited contralateral trunk tilt influence elbow varus torque? Summary of Key Findings: Four studies were included: all were labeled as "controlled" or "descriptive laboratory studies," representing cross-sectional observational analytic design. One study compared biomechanics of professional pitchers with and without ulnar collateral ligament reconstruction. Two studies measured biomechanics in college pitchers, one of which also included simulations of joint angles. The fourth study measured biomechanics of high school pitchers. All studies measured trunk tilt and its relationship to elbow varus torque, with 3 of the studies linking increased contralateral trunk tilt with increased elbow varus torque. Clinical Bottom Line: Moderate evidence indicated as contralateral trunk tilt increased, so did elbow varus torque, indicating trunk tilt may be a modifiable factor to decrease medial elbow loading during pitching. Strength of Recommendation: Majority consistent findings from the level 3 cross-sectional observational analytic designs suggest grade B evidence in support of trunk tilt as a factor in increasing elbow varus torque.

Anterior cruciate ligament reconstructed females who pass or fail a functional test battery do not exhibit differences in knee joint landing biomechanics asymmetry before and after exercise.

PURPOSE: A functional test battery (FTB) has been proposed to evaluate the readiness of return to activity after ACLR. However, there is limited evidence documenting the usefulness of an FTB. Therefore, the purpose of the current investigation was to compare knee joint landing biomechanics asymmetry during double-leg jump landing (DLJL) and single-leg jump cutting (SLJC) between healthy females and ACLR females who pass (ACLR-pass) or fail (ACLR-fail) an FTB before and after the completion of a sustained exercise protocol. METHOD: Eighteen ACLR females (ten ACLR-pass and eight ACLR-fail) and twelve healthy females performed an FTB including The 2000 International Knee Documentation Committee Subjective Knee Evaluation Form, the Knee Outcome Survey Activities of Daily Living Scale, quadriceps strength, and single-leg hop tests. DLJL and SLJC knee joint biomechanics asymmetry were measured before and after exercise. RESULTS: During DLJL, there were significant main effects of group on peak anterior tibial shear force (ATSF) asymmetry [F(2,27) = 3.86, p < 0.05, [Formula: see text] = 0.214] and peak vertical ground reaction force (vGRF) asymmetry [F(2,27) = 3.34, p = 0.05, [Formula: see text] = 0.198]. During SLJC, there was a significant group main effect for peak ATSF asymmetry [F(2,27) = 3.494, p = 0.04, [Formula: see text] = 0.206]. CONCLUSION: ACLR-fail exhibited greater asymmetry in peak ATSF during DLJL and SLJC compared to healthy females. In addition, ACLR-pass exhibited greater asymmetry in peak ATSF and peak vGRF during DLJL and SLJC, respectively, compared to healthy females. However, ACLR-fail did not exhibit any significant differences in landing biomechanics asymmetry during either task compared with ACLR-pass. Furthermore, the completion of a sustained exercise protocol did not affect knee joint landing biomechanics asymmetry across groups. LEVEL OF EVIDENCE: II.

The Effects of the Short Foot Exercise on Navicular Drop: A Critically Appraised Topic.

Clinical Scenario: Deformation of the arch, as measured by navicular drop (ND), is linked to lower-extremity musculoskeletal injuries. The short foot exercise (SFE) has been used to strengthen the intrinsic foot muscles that support the arch. Clinical Question: Does the SFE decrease ND in healthy adults? Summary of Key Findings: Three studies that examined the use of the SFE on ND were included. A randomized control trial that compared the SFE to a towel-curl exercise and a control group found no significant differences between the 3 groups. A randomized control trial compared the SFE to the use of arch support insoles in individuals with a flexible flatfoot and found a significant improvement in the SFE group. A prospective cohort study, without a control group, reported a significant decrease in ND following a 4-week SFE intervention without a regression at an 8-week follow-up. Overall, two of the three studies reported a significant reduction in ND following an SFE. Clinical Bottom Line: There is preliminary data supporting the use of the SFE to decrease ND-particularly in individuals with a flexible flatfoot. However, issues with the study designs make it difficult to interpret the data. Strength of Recommendation: Due to limited evidence, there is grade B evidence to support the use of the SFE to decrease ND.

Deceleration Profiles Between the Penultimate and Final Steps of Planned and Reactive Side-Step Cutting.

CONTEXT: Noncontact anterior cruciate ligament injury often occurs during rapid deceleration and change-of-direction maneuvers. These activities require an athlete to generate braking forces to slow down the center of mass and change direction in a dynamic environment. During preplanned cutting, athletes can use the penultimate step for braking before changing direction, resulting in less braking demand during the final step. During reactive cutting, athletes use different preparatory movement strategies during the penultimate step when planning time is limited. However, possible differences in the deceleration profile between the penultimate and final steps of preplanned and reactive side-step cuts remain unknown. OBJECTIVE: To comprehensively evaluate deceleration during the penultimate and final steps of preplanned and reactive cutting. DESIGN: Cross-sectional study. SETTING: Laboratory. PATIENTS OR OTHER PARTICIPANTS: Thirty-six women (age = 20.9 ± 1.7 years, height = 1.66 ± 0.07 m, mass = 62.4 ± 8.7 kg). INTERVENTION: Participants completed 90° side-step cutting maneuvers under preplanned and reactive conditions. MAIN OUTCOME MEASURE(S): Approach velocity, velocity at initial contact, and cutting angle were compared between conditions. Stance time, deceleration time, and biomechanical indicators of deceleration were assessed during the penultimate and final steps of preplanned and reactive 90° cuts. Separate repeated-measures analysis-of-variance models were used to assess the influence of step, condition, and their interaction on the biomechanical indicators of deceleration. RESULTS: Approach velocity (P = .69) and velocity at initial contact of the penultimate step (P = .33) did not differ between conditions. During reactive cutting, participants achieved a smaller cutting angle (P < .001). We identified a significant step-by-condition interaction for all biomechanical indicators of deceleration (P values < .05). CONCLUSIONS: A lack of planning time resulted in less penultimate step braking and greater final step braking during reactive cutting. As a result, participants exhibited a decreased cutting angle and longer stance time during the final step of reactive cutting. Improving an athlete's ability to respond to an external stimulus may facilitate a more effective penultimate step braking strategy that decreases the braking demand during the final step of reactive cutting.

Single-Legged Triple-Hop Propulsion Strategies in Females With and Those Without a History of Anterior Cruciate Ligament Reconstruction.

CONTEXT: The single-legged triple hop is a commonly used functional task after anterior cruciate ligament reconstruction (ACLR). Recently, researchers have suggested that individuals may use a compensatory propulsion strategy to mask underlying quadriceps dysfunction and achieve symmetric hop performance. OBJECTIVE: To evaluate the performance and propulsion strategies used by females with and those without ACLR during a single-legged triple hop. DESIGN: Cross-sectional study. SETTING: Laboratory. PATIENTS OR OTHER PARTICIPANTS: A total of 38 females, 19 with ACLR (age = 19.21 ± 1.81 years, height = 1.64 ± 0.70 m, mass = 63.79 ± 7.59 kg) and 19 without ACLR (control group; age = 21.11 ± 3.28 years, height = 1.67 ± 0.73 m, mass = 67.28 ± 9.25 kg). MAIN OUTCOME MEASURE(S): Hop distance and limb symmetry index (LSI) were assessed during a single-legged triple hop for distance. Propulsion strategies were evaluated during the first and second hops of the single-legged triple hop. Separate 2-way analysis-of-variance models were used to examine the influence of ACLR, joint, and their interaction on mechanical joint work, moment impulse, and the relative joint contributions to total work and moment impulse in females with and those without a history of ACLR. RESULTS: Despite achieving a mean LSI of approximately 96%, the ACLR group produced less total work in the reconstructed than the uninvolved limb during single-legged triple-hop propulsion (first hop: t18 = -3.73, P = .002; second hop: t18 = -2.55, P = .02). During the first and second hops, the reconstructed knee generated 19.3% (t18 = -2.33, P = .03) and 27.3% (t18 = -4.47, P < .001) less work than the uninvolved knee. No differences were identified between the involved and uninvolved limbs of the ACLR group in moment impulse (first hop: t18 = -0.44, P = .67; second hop: t18 = -0.32; P = .76). Irrespective of limb or group, the ankle was the largest contributor to both work and moment during both the first and second hops (P < .001). CONCLUSIONS: Clinicians should exercise caution when using a single-legged triple hop as a surrogate for restored lower extremity function in females post-ACLR. This recommendation is driven by the compelling findings that knee-joint deficits persisted in the reconstructed limb despite an LSI of approximately 96% and, regardless of previous injury status, single-legged triple-hop propulsion was predominantly driven by the ankle.

Single-Legged Triple-Hop Propulsion Strategies in Females With and Those Without a History of Anterior Cruciate Ligament Reconstruction.

CONTEXT: The single-legged triple hop is a commonly used functional task after anterior cruciate ligament reconstruction (ACLR). Recently, researchers have suggested that individuals may use a compensatory propulsion strategy to mask underlying quadriceps dysfunction and achieve symmetric hop performance. OBJECTIVE: To evaluate the performance and propulsion strategies used by females with and those without ACLR during a single-legged triple hop. DESIGN: Cross-sectional study. SETTING: Laboratory. PATIENTS OR OTHER PARTICIPANTS: A total of 38 females, 19 with ACLR (age = 19.21 ± 1.81 years, height = 1.64 ± 0.70 m, mass = 63.79 ± 7.59 kg) and 19 without ACLR (control group; age = 21.11 ± 3.28 years, height = 1.67 ± 0.73 m, mass = 67.28 ± 9.25 kg). MAIN OUTCOME MEASURE(S): Hop distance and limb symmetry index (LSI) were assessed during a single-legged triple hop for distance. Propulsion strategies were evaluated during the first and second hops of the single-legged triple hop. Separate 2-way analysis-of-variance models were used to examine the influence of ACLR, joint, and their interaction on mechanical joint work, moment impulse, and the relative joint contributions to total work and moment impulse in females with and those without a history of ACLR. RESULTS: Despite achieving a mean LSI of approximately 96%, the ACLR group produced less total work in the reconstructed than the uninvolved limb during single-legged triple-hop propulsion (first hop: t18 = -3.73, P = .002; second hop: t18 = -2.55, P = .02). During the first and second hops, the reconstructed knee generated 19.3% (t18 = -2.33, P = .03) and 27.3% (t18 = -4.47, P < .001) less work than the uninvolved knee. No differences were identified between the involved and uninvolved limbs of the ACLR group in moment impulse (first hop: t18 = -0.44, P = .67; second hop: t18 = -0.32; P = .76). Irrespective of limb or group, the ankle was the largest contributor to both work and moment during both the first and second hops (P < .001). CONCLUSIONS: Clinicians should exercise caution when using a single-legged triple hop as a surrogate for restored lower extremity function in females post-ACLR. This recommendation is driven by the compelling findings that knee-joint deficits persisted in the reconstructed limb despite an LSI of approximately 96% and, regardless of previous injury status, single-legged triple-hop propulsion was predominantly driven by the ankle.

Effects of homosynaptic depression on spectral properties of H-reflex recordings.

The purpose of this study was to determine the effects of homosynaptic depression (HD) on spectral properties of the soleus (SOL) H-reflex. Paired stimulations, separated by 100 ms, were used to elicit an unconditioned and conditioned H-reflex in the SOL muscle of 20 participants during quiet standing. Wavelet and principal component analyses were used to analyze features of the time-varying spectral properties of the unconditioned and conditioned H-reflex. The effects of HD on spectral properties of the H-reflex signal were quantified by comparing extracted principal component scores. The analysis extracted two principal components: one associated with the intensity of the spectra and one associated with its frequency. The scores for both principal components were smaller for the conditioned H-reflex. HD decreases the spectral intensity and changes the spectral frequency of H-reflexes. These results suggest that HD changes the recruitment pattern of the motor units evoked during H-reflex stimulations, in that it not only decreases the intensity, but also changes the types of motor units that contribute to the H-reflex signal.

Spinal motor control differences between the sexes.

Activity-related knee joint dysfunction is more prevalent in females than males. One explanation for the discrepancy is differences in movement patterns between the sexes. However, the underlying mechanisms responsible for these differences remain unidentified. This study tested spinal motor control mechanisms influencing motor neuron pool output and subsequent muscle activation in 17 males and 17 females. The following variables were assessed at the soleus: the gain of the unconditioned H-reflex, gain of both intrinsic pre-synaptic inhibition (IPI) and extrinsic pre-synaptic inhibition (EPI), the level of recurrent inhibition (RI), the level of supraspinal drive determined by the ratio of the Vmax:Mmax (V-wave), electromechanical delay (EMD) and the rate of force development (RFD). The Wilks Lambda multivariate test of overall differences among groups was significant (p = 0.031). Univariate between-subjects tests revealed males had greater RI (p = 0.042). However, the sexes did not differ on any of the other variables tested. In conclusion, the sexes differ on modulation of spinal motor control. Specifically, RI, a post-synaptic regulator of force output, was greater in males.

The Effect of a Statewide Policy on High School Emergency Action Plans.

Institutions sponsoring athletics must be prepared for emergencies. Due to this, more governing bodies are requiring a sports-related emergency action plan (EAP). Yet, the effects of these policies are unknown. We compared adoption of EAPs and associated best practices in Oregon high schools before and after a policy requiring an EAP. Athletic directors were invited to complete a survey during the year before the policy went into effect and again the following year. We assessed whether the school had a written EAP and if they did, was the EAP venue specific, available at the venue, distributed to personnel, and annually reviewed and rehearsed. Pre/post-policy proportions were analyzed using Fisher exact tests for all schools and then schools that completed both surveys. There was a significant increase of schools that reported having an EAP after the policy went into effect (all schools: 55% to 99% [p < 0.001] and schools responding both years: 60% to 98% [p < 0.001]). Venue specific EAPs also significantly increased but only when analyzing all responses (59% to 71% [p = 0.03]). No best practice recommendations related to EAP availability, distribution, review, or rehearsal changed after the policy. Schools met the minimum requirements of the policy, but other related best practices did not significantly improve.

Spinal reflex excitability and homosynaptic depression after a bout of whole-body vibration.

Although whole-body vibration (WBV) affects neuromuscular performance, it remains unclear whether the effects are due to spinal reflex potentiation or inhibition, or differ between muscle groups. This study aimed to identify the effect of WBV on measures of spinal reflex excitability (H-reflex) and homosynaptic depression (HD) in the soleus (SOL) and medial gastrocnemius (MG) muscles. H-reflex and HD measurements were made in the SOL and MG muscle of 20 participants before and after a bout of WBV. H-reflex and HD were measured every 15 seconds for 10 minutes post-WBV and averaged at 1-minute increments. H-reflex amplitude was depressed for the first minute post-vibration, whereas the effect of HD was reduced for the first 2 minutes post-vibration. WBV significantly decreases spinal reflex excitability and HD, but it does so transiently and independent of muscle group.

Greater explosive quadriceps strength is associated with greater knee flexion at initial contact during landing in females.

This study investigated the influences of explosive quadriceps strength and landing task on sagittal plane knee biomechanics. Forty female participants performed isometric knee extensions on a dynamometer and had lower extremity biomechanics assessed during double-leg jump-landings (DLJL) and single-leg jump-cuts (SLJC). Explosive quadriceps strength was quantified by calculating rate of torque development (RTD) between torque onset and 100 ms after onset on a dynamometer. Participants were stratified into high and low RTD groups. Landing biomechanics were compared using 2 (Group) × 2 (Task) mixed-model ANOVAs. The relationships between quadriceps RTD and landing biomechanics were also assessed using simple, bivariate correlations. Across RTD groups, greater knee flexion at initial contact (KFIC), peak vertical ground reaction force, peak anterior tibial shear force, and peak internal knee extension moment, and lesser peak knee flexion was observed during SLJC compared to DLJL. The high RTD group exhibited significantly greater KFIC than the low RTD group across landing tasks. Greater quadriceps RTD was significantly associated with greater KFIC during SLJC, but not during DLJL. As landing with lesser KFIC is a risk factor for ACL injury, greater explosive quadriceps strength capacity might be beneficial for facilitating the use of safer landing mechanics during athletic tasks.

Photic Regulation of Circadian Rhythms and Voluntary Ethanol Intake: Role of Melanopsin-expressing Intrinsically Photosensitive Retinal Ganglion Cells.

"Non-image-forming" (NIF) effects of light are mediated primarily by a subset of intrinsically photosensitive retinal ganglion cells (ipRGCs) expressing the photopigment, melanopsin (OPN4). These NIF functions include circadian entrainment, pupillary reflexes, and photic effects on sleep, mood, and cognition. We recently reported that mice of multiple genotypes exhibit reduced voluntary ethanol intake under both constant darkness (DD) and constant light (LL) relative to standard light-dark (LD) conditions. In the present study, we sought to determine whether these effects are mediated by melanopsin-expressing ipRGCs and their potential relationship to photic effects on the circadian system. To this end, we examined the effects of environmental lighting regimen on both ethanol intake and circadian activity rhythms in a genetically engineered mouse model (Opn4aDTA/aDTA) in which melanopsin expression is completely blocked while ipRGCs are progressively ablated due to activation of attenuated diphtheria toxin A (aDTA) transgene under the control of the Opn4 promoter. As expected from previous studies, Opn4aDTA/aDTA mice displayed dramatic attenuation of circadian photosensitivity, but surprisingly, showed identical suppression of ethanol intake under both DD and LL as that seen in controls. These results demonstrate that the effects of lighting regimen on voluntary ethanol intake are independent of melanopsin-expressing ipRGCs and ipRGC-mediated photic effects on the circadian system. Rather, these effects are likely mediated by classical retinal photoreceptors and central pathways.

Explosive Quadriceps Strength and Landing Mechanics in Females with and without Anterior Cruciate Ligament Reconstruction.

Lower explosive quadriceps strength, quantified as rate of torque development (RTD), may contribute to landing mechanics associated with anterior cruciate ligament (ACL) injury risk. However, the association between quadriceps RTD and landing mechanics during high demand tasks remains unclear. Therefore, this study investigated the influence of quadriceps RTD on sagittal plane landing mechanics during double-leg jump landings (DLJL) and single-leg jump cuts (SLJC) in females with and without ACL reconstruction (ACLR). Quadriceps RTD was measured during isometric muscle contractions. Landing mechanics were collected during DLJL and SLJC tasks. Separate stepwise multiple linear regression models determined the amount of variance in sagittal plane landing mechanics that could be explained by quadriceps RTD, group (ACLR or Control), and their interaction. The results indicate that greater quadriceps RTD is associated with lower loading rate (p = 0.02) and longer time to peak vertical ground reaction force (p = 0.001) during SLJC, regardless of ACLR status. As greater loading rate may lead to higher risk of ACL injuries and post-traumatic knee osteoarthritis post-ACLR, explosive muscle strength interventions might be useful for individuals with and without ACLR to facilitate the use of safer landing mechanics.

Cost-Benefit of Hiring Athletic Trainers in Oregon High Schools From 2011-2014.

CONTEXT: Hiring athletic trainers (ATs) in high schools may lower medical payments by third-party payers such as Medicaid or commercial insurers by reducing injury risks or may increase medical payments due to more referrals to other health care providers. To date, evidence is lacking on the actual financial effect of high school ATs based on an analysis of medical claims. OBJECTIVE: To assess the overall cost-benefit of hiring ATs in Oregon high schools based on medical claims data across years. DESIGN: Cost-benefit study. SETTING: Oregon public high schools. PATIENTS OR OTHER PARTICIPANTS: Patients aged 14 to 18 years old. MAIN OUTCOME MEASURE(S): We analyzed the 2011-2014 limited dataset from the Oregon Health Authority's All Payer All Claims database. Paired t tests were used to compare claims payments at the zip code level between periods of having and not having ATs in Oregon high schools. We also used the percentage of AT effort to adjust for AT investment. The main outcome measure was the return on investment associated with hiring ATs in high schools. RESULTS: The presence of ATs in Oregon high schools may have had different effects on medical payments for Medicaid and commercial insurance. With every dollar invested in hiring ATs in Oregon public high schools from 2011 to 2014, Medicaid payments increased by 24 cents per month at the zip code level, while commercial insurance payments decreased by 24 cents, although the changes were not statistically significant. CONCLUSIONS: Hiring ATs in an outreach model for high schools may not necessarily generate medical savings for Medicaid or commercial insurers. Further research is needed to determine if the lack of cost savings in our study was a factor of the employment model, resulted from increased health care utilization, or reflected the need for ATs to deliver more on-site AT services.

The impact of high school athletic trainer services on medical payments and utilizations: a microsimulation analysis on medical claims.

BACKGROUND: Increasing athletic trainer (AT) services in high schools has attracted widespread interest across the nation as an effective instrument to manage injuries and improve children's health, but there is a lack of evidence on potential medical savings. Our study aimed to address this knowledge gap and provide evidence of AT impacts on medical payments and utilizations to inform public policy decision. METHODS: We obtained medical claims of patients aged 14 to 18 years from the 2011-2014 Oregon All Payer All Claims limited dataset. We calculated payer payments and utilizations for medical claims under AT's scope of practice. We used zip codes to link patients with the enrollment boundaries of Oregon public high schools, which were classified as either "AT group" or "non-AT group". We implemented an innovative microsimulation analysis to address the uncertainty of linkage between children and schools. RESULTS: Our analysis included 64,115 and 84,968 eligible children with Medicaid and commercial insurance, respectively. Associated with high school AT services, Medicaid saved an average of $64 per patient during the study period, while commercial insurance payment rarely changed. AT services may reduce emergency visits for both insurance types but increase total visits for commercially insured patients. CONCLUSIONS: Our study provides evidence for the differential impacts of AT services on medical payments and utilizations. The legislators should consider to allocate funds for high schools to directly employ ATs. This will encourage ATs to work to their highest ability to improve children's wellbeing while containing avoidable medical cost.

Normalization influences knee abduction moment results: Could it influence ACL-injury research, too?

OBJECTIVES: Normalization of joint moments to reduce anthropometric influences prior to making group comparisons is a widely-accepted practice. However, a seminal prospective study reported greater non-normalized knee abduction moment (KAM) in nine females who subsequently sustained an ACL injury. It is not clear if this finding may have been influenced by the fact that the ACL-injured females were on average 3.6cm taller and 2.4kg heavier than uninjured females. DESIGN: Cross-sectional. METHODS: Peak KAM was identified in thirty-six females completing jump landings. A custom software program randomly divided participants into two groups that were compared on: (1) non-normalized KAM, (2) KAM normalized to body mass, and (3) KAM normalized to body height times weight a total of 500,000 times and the results categorically coded for statistical significance (α≤0.05). For the 10,591 iterations in which one group was 3-4cm taller and 2-3kg heavier, the agreement between results obtained using non-normalized versus normalized data were assessed using non-parametric analyses. RESULTS: Despite moderate-strong agreement between the results obtained using non-normalized and normalized data (Κ=0.614-0.744), a significant effect of normalization on the interpretation of group differences in peak KAM was identified (p<0.001). In 30.4-41.9% of the cases in which non-normalized KAM was deemed significantly different between groups, no group differences were identified when using normalized KAM. CONCLUSIONS: While it is unlikely the magnitude of the difference in non-normalized KAM identified prospectively in ACL-injured females was attributable solely to anthropometric differences, caution should be exercised when evaluating research findings reporting non-normalized KAM.

Sports-Related Emergency Preparedness in Oregon High Schools.

BACKGROUND: Best practice recommendations for sports-related emergency preparation include implementation of venue-specific emergency action plans (EAPs), access to early defibrillation, and first responders-specifically coaches-trained in cardiopulmonary resuscitation and automated external defibrillator (AED) use. The objective was to determine whether high schools had implemented these 3 recommendations and whether schools with a certified athletic trainer (AT) were more likely to have done so. HYPOTHESIS: Schools with an AT were more likely to have implemented the recommendations. STUDY DESIGN: Cross-sectional study. LEVEL OF EVIDENCE: Level 4. METHODS: All Oregon School Activities Association member school athletic directors were invited to complete a survey on sports-related emergency preparedness and AT availability at their school. Chi-square and Fisher exact tests were used to analyze the associations between emergency preparedness and AT availability. RESULTS: In total, 108 respondents (37% response rate) completed the survey. Exactly half reported having an AT available. Only 11% (95% CI, 6%-19%) of the schools had implemented all 3 recommendations, 29% (95% CI, 21%-39%) had implemented 2, 32% (95% CI, 24%-42%) had implemented 1, and 27% (95% CI, 19%-36%) had not implemented any of the recommendations. AT availability was associated with implementation of the recommendations (χ2 = 10.3, P = 0.02), and the proportion of schools with ATs increased with the number of recommendations implemented (χ2 = 9.3, P < 0.01). Schools with an AT were more likely to implement venue-specific EAPs (52% vs 24%, P < 0.01) and have an AED available for early defibrillation (69% vs 44%, P = 0.02) but not more likely to require coach training (33% vs 28%, P = 0.68). CONCLUSIONS: Despite best practice recommendations, most schools were inadequately prepared for sports-related emergencies. Schools with an AT were more likely to implement some, but not all, of the recommendations. Policy changes may be needed to improve implementation. CLINICAL RELEVANCE: Most Oregon high schools need to do more to prepare for sports-related emergencies. The results provide evidence for sports medicine professionals and administrators to inform policy changes that ensure the safety of athletes.

Greater Hip Extension but Not Hip Abduction Explosive Strength Is Associated With Lesser Hip Adduction and Knee Valgus Motion During a Single-Leg Jump-Cut.

BACKGROUND: The relationships between hip abductor and extensor strength and frontal plane hip and knee motions that are associated with anterior cruciate ligament injury risk are equivocal. However, previous research on these relationships has evaluated relatively low-level movement tasks and peak torque rather than a time-critical strength measure such as the rate of torque development (RTD). HYPOTHESIS: Females with greater hip abduction and extension RTD would exhibit lesser frontal plane hip and knee motion during a single-leg jump-cutting task. STUDY DESIGN: Descriptive laboratory study. METHODS: Forty recreationally active females performed maximal isometric contractions and single-leg jump-cuts. From recorded torque data, hip extension and abduction RTD was calculated from torque onset to 200 ms after onset. Three-dimensional motion analysis was used to quantify frontal plane hip and knee kinematics during the movement task. For each RTD measure, jump-cut biomechanics were compared between participants in the highest (high) and lowest (low) RTD tertiles. RESULTS: No differences in frontal plane hip and knee kinematics were identified between high and low hip abduction RTD groups. However, those in the high hip extension RTD group exhibited lower hip adduction (high, 3.8° ± 3.0°; low, 6.5° ± 3.0°; P = .019) and knee valgus (high, -2.5° ± 2.3°; low, -4.4° ± 3.2°; P = .046) displacements during the jump-cut. CONCLUSION: In movements such as cutting that are performed with the hip in a relatively abducted and flexed position, the ability of the gluteus medius to control hip adduction may be compromised. However, the gluteus maximus, functioning as a hip abductor, may take on a pivotal role in controlling hip adduction and knee valgus motion during these types of tasks. CLINICAL RELEVANCE: Training with a specific emphasis on increasing explosive strength of the hip extensors may be a means through which to improve frontal plane hip and knee control during high-risk maneuvers such as cutting.

Factors influencing high school coaches' adoption of injury prevention programs.

OBJECTIVES: Despite documented efficacy of injury prevention programs (IPPs) to reduce sport-related lower extremity injury risk, there is evidence of a lack of widespread IPP adoption by high school coaches. This study identified factors related to non-adoption of IPPs by assessing coaches' knowledge, attitudes, and behaviors related to prevention programs and comparing attitudes between adopter and non-adopter coaches. DESIGN: Cross-sectional. METHODS: Head soccer and basketball coaches (n=141) from 15 Oregon high schools were invited to complete a web-based survey assessing their IPP-related knowledge, attitudes, and behaviors. RESULTS: Of the 66 coach respondents, 52% reported being aware of IPPs; 21% reported using an IPP with their team; and 9% reported having their student-athletes perform the IPP exactly as designed. No apparent differences in the attitudes toward the importance of injury prevention or the effectiveness of IPPs were identified between coaches that did and did not adopt an IPP. Perceptions that efficacious IPPs do not offer a relative advantage over coaches' existing practices, do not align with coaches' needs (compatibility), and are difficult to implement in their setting (complexity) emerged as key factors underlying coaches' decisions not to adopt a program. Of those that did report adopting an IPP, just 43% (6/14) reported implementing the program as designed. CONCLUSIONS: Improving preventative practices of high school coaches requires more than improved dissemination to increase coach awareness. To improve the rate of IPP adoption and implementation fidelity, coach education should directly address issues related to relative advantage, compatibility, and complexity.