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1.
ObjectivesFemales land with more knee valgus than males. While most studies have evaluated lower extremity mechanics during double leg landing, most sports require single-leg landing from a double or single leg takeoff. Further, knee movement occurs toward both varus and valgus during functional landing. The purpose of this study was to determine if differences exist between females and males in total frontal plane movement and velocity of the knee during single-leg landing.DesignExperimental cohort.SettingMotion analysis laboratory.ParticipantsForty healthy, physically-active females (n = 20) and males (n = 20).Main outcome measuresThree-dimensional motion analysis was completed on the lower extremities during double-leg jumping followed by a single-leg landing. Student's t-tests (p ≤ 0.05) were used to determine if differences exist in frontal plane knee angles (valgus and varus excursion) and angular velocities between females and males.ResultsFemales demonstrated greater knee valgus and varus excursion, and valgus and varus velocities compared to males (p < 0.05).ConclusionsThese findings suggest that total movement in the frontal plane at the knee may be an important factor in injury mechanics in females. Further, single-leg landing from a functional jump should be considered when comparing landing biomechanics between females and males.  相似文献   

2.
ObjectivesTo determine whether individuals with and without Chronic Ankle Instability (CAI) can improve their ankle movement discrimination sensitivity by repeated exposure to an ankle proprioceptive task requiring landing.DesignA repeated-measures study.SettingUniversity laboratory.Participants24 university students, 11 with CAI and 13 without CAI.Main outcome measuresAnkle proprioception was measured using the Ankle Inversion Discrimination Apparatus for Landing (AIDAL) over 3 occasions: AIDAL-1 and AIDAL-2 separated with a 10-min interval, and AIDAL-3 at 24 h post AIDAL-2.ResultsBetter Cumberland Ankle Instability Tool (CAIT) questionnaire scores were correlated with higher AIDAL scores (rho = 0.465, p = 0.022). Two-way ANOVA showed a significant CAI main effect for step landing ankle inversion proprioception, with CAI worse (F = 8.410, p = 0.008), but the Time main effect across the 3 AIDAL tests was not significant (F = 1.552, p = 0.223).ConclusionsThe AIDAL assessment was sensitive in terms of discriminating between individuals with or without CAI. However, the step-down component of the AIDAL proprioceptive task was possibly too challenging. For CAI, physical therapy exercises should take into account the difficulty of the training task, so that a demonstrable learning effect can be achieved.  相似文献   

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ObjectivesHigher side-to-side asymmetry among female athletes compared to their male counterparts during bilateral athletic tasks such as landing from a jump has been proposed as a potential source of non contact knee injuries. However, the kinematic symmetry and potential sex differences during the initial (and most dangerous) phase of bilateral landings have not been examined. The objective of this project is to evaluate lower extremity kinematic asymmetry among recreational athletes during forward jump landing and drop landing tasks.DesignRepeated measures laboratory experiment.MethodsThirteen male and 15 female athletes performed landing tasks on a force plate while kinematic data were collected. Kinematic asymmetry between legs was calculated for the initial phase of landing for lower extremity kinematics. ANOVA tests and effect size calculations were used to measure the effect of sex, landing task and their interaction on kinematic asymmetry.ResultsAthletes exhibited higher asymmetry for knee valgus (d = 0.5, p = 0.006) and hip adduction (d = 0.5, p = 0.057) when performing forward compared to drop landings. Females landed with greater knee valgus asymmetry than males during forward landings (d = 0.7, p = 0.078) and with greater ankle abduction asymmetry during drop landings (d = 0.5, 0.091).ConclusionsFemale athletes exhibited greater frontal plane knee and ankle kinematic asymmetry than males during forward landings which may be related to the higher rate of ACL injury. Forward landings elicited greater hip adduction and knee valgus asymmetries than drop landings and, therefore it may be more appropriate for field testing when screening for asymmetries.  相似文献   

4.
ObjectiveTo compare lower limb strength and countermovement jump (CMJ) kinetics between elite female footballers with and without a history of anterior cruciate ligament reconstruction (ACLR), hamstring strain, or hip/groin injury.DesignCross-sectional.SettingField-based.Participants369 elite female Australian football, soccer and rugby league players aged 15–35.Main outcome measuresIsometric hip adductor and abductor strength, eccentric knee flexor strength, and CMJ vertical ground reaction forces, including between-leg asymmetry. Players reported their lifetime history of ACLR, and whether they had sustained a hamstring strain, or hip/groin injury in the previous 12-months.ResultsPlayers with a unilateral history of ACLR (n = 24) had significant between-leg asymmetry in eccentric knee flexor strength (mean = −6.3%, 95%CI = −8.7 to −3.9%, P < .001), isometric hip abductor strength (mean = −2.5%, 95%CI = −4.3 to −0.7%, P = .008), and CMJ peak landing force (mean = −5.5%, 95%CI = −10.9 to −0.1%, P = .046). Together, between-leg asymmetry in eccentric knee flexor strength, isometric hip abductor strength, and CMJ peak landing force distinguished between players with and without prior ACLR with 93% accuracy.ConclusionElite female footballers with a history of ACLR, but not hamstring or hip/groin injury, exhibit persistent between-leg asymmetries in lower limb strength and jump kinetics following a return to sport.  相似文献   

5.
ObjectivesInvestigate the impact of lace-up ankle braces on landing biomechanics.DesignWithin-subject repeated measures. Participants completed a drop jump, drop land, and netball-specific task in braced and unbraced conditions.SettingBiomechanical research laboratory.ParticipantsTwenty female high school netballers.Main outcome measuresLeg, knee, and ankle stiffness, knee/ankle stiffness ratio, knee and ankle sagittal excursion, peak vertical ground reaction force, time-to-peak vertical ground reaction force, and loading rate.ResultsIn the brace condition leg stiffness increased bilaterally during the drop land (ES = 0.21, 0.22), ankle stiffness increased bilaterally during the drop jump (ES = 0.37, 0.29) and drop land (ES = 0.40, 0.60), and knee/ankle stiffness ratio decreased in all three tasks (ES = −0.22 to −0.45). Ankle sagittal excursion decreased bilaterally during the drop jump (ES = −0.35, −0.53) and drop land (ES = −0.23, −0.46), and decreased in the lead limb during the netball jump (ES = −0.36). Knee excursion decreased bilaterally during the drop jump (ES = −0.36, −0.40) and in the lead limb during netball task (ES = −0.59). Lead limb TTP was greater during the netball jump (ES = 0.41).ConclusionsLace-up ankle braces may increase leg and joint stiffness and reduce joint excursion during landing but do not appear to affect landing forces. The observed effect on landing biomechanics may predispose young netballers to injury.  相似文献   

6.
BackgroundLanding-based measures of the knee are often used to assess risk of anterior cruciate ligament (ACL) injury and inform prevention strategies. There is less understanding of the ankle's influence on knee measures during landing.Objective1. Examine interactions of dynamic ankle measures alongside various subject and task characteristics on knee dynamics in vertical landing and 2. Determine whether ankle measures alone can estimate dynamic knee measures associated with ACL injury risk.DesignSystematic review and meta-analysis.MethodsElectronic databases Medline, EMBASE, CINAHL, Web of Science and Cochrane were screened for studies that included measurement of initial contact angles and internal joint moments of both the ankle and knee during landing in uninjured individuals.Results28 studies were included for analysis. Using 1144 landing trials from 859 individuals, RRelief F algorithm ranked dynamic ankle measures more important than landing task and subject characteristics in estimating knee dynamics. An adaptive boosting model using four dynamic ankle measures accurately estimated knee extension (R2 = 0.738, RMSE = 3.65) and knee abduction (R2 = 0.999, RMSE = 0.06) at initial contact and peak knee extension moment (R2 = 0.988, RMSE = 0.13) and peak knee adduction moment (R2 = 1, RMSE = 0.00).ConclusionsDynamic ankle measures can accurately estimate initial contact angles and peak moments of the knee in vertical landing, regardless of landing task or individual subject characteristics. This study provides a theoretical basis for the importance of the ankle in ACL injury prevention.  相似文献   

7.
BackgroundPatients demonstrate decreased knee loading and energy absorption after anterior cruciate ligament reconstruction (ACLR). This study aimed to determine the differences in the contribution of joints to the absorbed energy between athletes with and without radiological signs of knee OA 2 years after ACLR during drop jump (DJ) landing from 20, 30, and 40 cm.MethodsForty-one (level I/II) athletes 2 years after ACLR participated in this cross-sectional study and completed motion analysis testing of DJ. Proportional contribution of the joints (foot, ankle, knee, and hip) to the absorbed energy were computed. Posterior-anterior bent-knee radiographs were completed and graded in the medial compartment of the reconstructed knee using the Kellgren-Lawrence (KL) system (OA group: KL ≥2; Non-OA group: KL<2)ResultsThirteen (31.7%) athletes showed radiological signs of knee OA in the medial compartment. There was a significant joint-by-group-by-limb interaction for the contribution of joints to absorbed energy during DJ 40 cm (p ≤ 0.019) and a joint-by-group interaction for the contribution of joints during DJ 20 cm (p = 0.018). The OA group had a lower involved knee (p = 0.043) and higher involved hip contributions (p = 0.014) compared to the Non-OA group, and the non-involved knee (p = 0.007). While the Non-OA group had a lower involved ankle contribution (p = 0.045) compared to their non-involved ankle during DJ 40 cm. The OA group also had higher involved hip contribution than the Non-OA group (p = 0.010), lower involved knee (p = 0.002), and higher involved hip contribution than the non-involved limb during DJ 20 cm.SignificanceThe OA group may have adopted a compensatory pattern characterized by a decreased involved knee and increased involved hip to attenuate absorbed energy compared to the Non-OA group and their non-involved limb. The contribution of joints to the absorbed energy during DJ landing might be used as an assessment tool to identify patients with radiological signs of knee OA after ACLR.  相似文献   

8.
ObjectiveDetermine how lower limb neuromuscular control changes over the course of a competitive soccer season.DesignRepeated measures.SettingAcademy soccer club.Participants43 male youth soccer players (age 13.1 ± 2.2 yr; height 160.1 ± 15.7 cm; body mass 49.4 ± 14.3 kg; maturity offset 0.2 ± 1.9 yr).Main outcome measuresPre-, mid- and end of season assessments of peak landing forces during single leg 75% horizontal hop and stick (75%HOP) and a single leg countermovement jump (SLCMJ), single leg hop for distance (SLHD), knee valgus during the tuck jump assessment (TJA) and inter-limb symmetries.ResultsHop distance increased significantly. Absolute peak landing forces in the left leg during the SLCMJ and 75%HOP increased significantly, with significant increases also present in the same leg for SLCMJ relative peak landing force. TJA knee valgus score was reduced in the right leg, but remained at a ‘moderate’ level in the left knee.ConclusionNeuromuscular control, as evidenced by increased absolute and relative peak landing forces, appears to reduce over the course of a competitive season. Young soccer players should engage in neuromuscular training throughout the season to offset any decrements in neuromuscular control and to facilitate appropriate landing strategies.  相似文献   

9.
BackgroundAnterior cruciate ligament (ACL) injury is one of the most serious knee injuries and occurs frequently during exercise. Altered hip and ankle muscle co-contraction patterns may contribute to dynamic knee valgus and ACL injury mechanisms. Lack of dynamic control of ground reaction force (GRF) is known to be contributing factor for ACL injury by placing excessive force on passive structures. Muscle co-contraction is a dynamic mechanism for GRF absorption. Therefore, any alterations in co-contraction might be a risk factor for ACL injury. Ligament dominance is a term to define individuals who rely more on ACL ligament for GRF control.Research questionThis study aimed to compare the muscle co-contraction patterns of distal and proximal knee muscles during single leg landing in female athletes with and without ligament dominance.MethodsThis is a cross-sectional study. A total of 54 female athletes were assigned to the healthy (n = 27) and ligament dominance (n = 27) group based on their Tuck Jump test scores. The electromyography activity of the gluteus medius, adductor longus, tibialis anterior, peroneus longus, medial and lateral gastrocnemius was measured by an electromyography in drop down a 30-cm-high stair. A Multivariate Analysis of Variance (MANOVA) was used for statistical analysis (p ≤ 0.05).ResultsThe two groups demonstrated an overall significantly different muscle co-contraction patterns (P < 0.05). There was a decreased in co-contraction of proximal group and an increased co-contraction in the distal muscles in ligament dominant group.SignificanceThe findings have provided evidence to support the notion of neuromuscular imbalances in ligament dominance deficit. These findings can be useful for the coaches and experts to design preventive exercises and modify the current programs for the people affected by ligament dominance.  相似文献   

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BackgroundSeveral prior studies involving “expected” single-leg landings have not succeeded in establishing a difference between copers and a control group.Research questionDoes expected and unanticipated single-leg landing affect dynamic postural stability in lateral ankle sprain individuals with chronic ankle instability (CAI), copers, and controls?MethodsIn this prospective cross-sectional study, physically active adults with CAI (n = 12), copers (n = 12), and controls (n = 12) were included. Participants performed expected single-leg landing by stepping off a 30-cm box. They also performed unanticipated landings including side-step cutting, side-step cutting at 60°, single-leg landing, and forward stepping. The expected and unanticipated conditions of each groups were compared in terms of time to stabilization (TTS) and center of pressure (COP) for the anterior-posterior (AP) and medial-lateral (ML) conditions. To analyze the data, a mixed-model one-way analysis of variance and a Tukey-Kramer post hoc test were performed.ResultsA significant condition × group interaction was observed in only TTS ML, with the CAI group demonstrating a significantly longer TTS ML than the coper (p < 0.001) and control (p < 0.001) groups during unanticipated trials. In addition, group interaction effects were observed for COP AP and TTS AP. The coper group demonstrated significantly longer COP AP and TTS AP than the control group (p < 0.001).SignificanceThe CAI group demonstrated a significantly longer TTS ML than the coper and control groups during the unanticipated condition, and the coper group demonstrated significantly longer TTS AP and COP AP than the control group. Thus, longer COP AP and TTS AP sway time in the coper group may be a protection mechanism, allowing greater freedom in the AP plane while quickly controlling ML sway and preventing lateral ankle sprains. These findings can help in the prevention of lateral ankle sprains and assessment of dynamic postural control.  相似文献   

12.
ObjectiveTo investigate the efficacy of two ‘NetballSmart’, netball specific warm-ups in improving landing technique measures in New Zealand secondary school netball players.DesignMulti-site cluster experimental trial.Participants77 youth participants, mean ± SD age = 15.8 ± 0.9 were recruited from secondary school netball teams.Setting12 teams from 6 schools performed either the NetballSmart Dynamic Warm-up (NSDW) (n = 37); or Power warm-up (PWU) (n = 40), three times a week for 12 weeks. All players within a school (2 teams) were assigned the same warm-up, avoiding treatment contamination.Main outcome measuresA series of unilateral and bilateral drop vertical jumps on to a portable force plate were completed by all participants. Measures included peak vertical ground reaction force (GRF) for single-leg and bilateral landings; frontal plane projection angle (FPPA) for right and left single-leg landings and Landing error scoring system (LESS) for bilateral landings. Paired t-tests were used to assess mean differences pre and post the warm-up. Generalised linear mixed effects models were developed to evaluate the effects between the NSDW and PWU groups.ResultsSignificant improvements were found in all the landing technique outcome measures for both warm-up groups (ES Range- GRF = −0.6 to −1.1; FPPA = 0.8 to 1.2; LESS = −1.6 to-3.2; p < 0.05). Results of mixed effects models revealed that there was only a significantly greater improvement in LESS for the PWU group (β = −0.30, p = 0.001).ConclusionResults show both warm-ups can improve landing technique measures in youth secondary school netball players. It is recommended that coaches should consider implementing one of the two warm-ups in their netball programmes. Their choice of warm-up will likely be dependent on their environment and time demands.  相似文献   

13.
ContextNon-contact ACL injuries are common in female athletes during landing tasks. Post-trial performance-based feedback may be an effective method to reduce landing forces and knee valgus during landing. Information regarding the retention of these changes based on such training is generally lacking for weekly and monthly retention.ObjectiveTo determine the effectiveness of post-trial feedback training to promote and retain changes in vertical ground reaction force (vGRF) and knee to ankle (K:A) ratio during a dual task drop landing in female collegiate athletes.DesignRepeated measures;SettingUniversity campus.Participants22 female collegiate athletes.Materials and methodsDual task drop landings were performed over 4 successive weeks with immediate post trial feedback on peak vGRF, symmetry, and K:A ratio. K:A ratio was a surrogate measure for knee valgus in drop landing.ResultsSignificant decreases in vGRF and increases in K:A ratio were found within training sessions (p = .000). Both variables were retained each week over the 4 weeks.ConclusionUsing a custom portable clinical feedback system may be an effective tool in reducing peak vGRFs and knee abduction angles during a drop landing over a 4-week period in female collegiate athletes.  相似文献   

14.
ContextIn both research and clinical settings there is an assumption of symmetry between limbs in landing. However, development of a preferred limb side is a natural occurrence. It is not well established how limb dominance affects landing mechanics in a unilateral or bilateral landing.ObjectiveTo investigate sagittal plane mechanics between dominant and non-dominant legs in both unilateral and a bilateral landing tasks.DesignCross-sectional study.SettingLaboratory environment.Participants148 male athletes.Main outcome measuresSagittal plane kinematics (hip, knee, and ankle flexion) at initial contact and maximum knee flexion, and total excursion of the movement.ResultsNo significant differences were found between limbs in the unilateral landing. Knee flexion (p = 0.02) and hip flexion (p = 0.00) were significantly different between dominant and non-dominant limbs at initial contact in the bilateral landing. Knee flexion total excursion (p = 0.04) and hip flexion total excursion (p = 0.03) in the bilateral landing were also significantly different between limbs.ConclusionsLower limb symmetry was observed for the unilateral landing. Minimal, yet significant, asymmetries (less than 2°) were present during the bilateral landing. This finding justifies the continued use of the dominant limb in research and clinical settings.  相似文献   

15.
ObjectivesTo investigate if maturity status was associated with injury risk in male academy soccer players.DesignProspective cohort surveillance study.SettingProfessional soccer academies.Participants501 players (aged 9–23 years) from eight academies in England, Spain, Uruguay and Brazil.Main outcome measuresPlayers were grouped by maturity offset as pre-peak height velocity (PHV), circa-PHV, post-PHV or adult. Injury prevalence proportion (IPP) and days missed were recorded for one season per player, with training/match exposure recorded in a sub-sample (n = 166).ResultsIPP for all injuries combined increased with advancing maturity, with circa-PHV (p = 0.032), post-PHV (p < 0.001) and adult (p < 0.001) higher than pre-PHV. IPP was higher in post-PHV and adult than pre-PHV for non-contact (p = 0.001 and p = 0.012), soft-tissue (both p < 0.001), non-contact soft-tissue (p < 0.001 and p = 0.005), muscle (both p < 0.001), thigh (both p < 0.001), ankle (p = 0.035 and p = 0.007) and hamstring injuries (p = 0.041 and p = 0.017). Ligament/tendon IPP was greater in adult versus pre-PHV (p = 0.002). IPP for growth-related injuries was lower in post-PHV than pre-PHV (p = 0.039). Injury incidence rates (n = 166) exhibited similar patterns to IPP in the full cohort.ConclusionsInjury patterns were similar between post-PHV and adult academy players but, crucially, relatively more of these groups suffered injuries compared to pre- and circa-PHV (except growth-related injuries).  相似文献   

16.
ObjectiveTo investigate the effect of rigid ankle tape on functional performance, self-efficacy and perceived stability, confidence and reassurance during functional tasks in participants with functional ankle instability.DesignClinical measurement, crossover design.MethodsParticipants (n = 25) with functional ankle instability (Cumberland Ankle Instability Score < 25) were recruited from university students and sporting clubs. Participants performed five functional tests with and without the ankle taped. The tests were: figure-8 hopping test, hopping obstacle course, star excursion balance test (SEBT), single-leg stance and stair descent test. Secondary outcome measures were self-efficacy and perception measures.ResultsRigid tape significantly decreased the stair descent time by 4% (p = 0.014), but had no effect on performance in the other tests. Self-efficacy increased significantly (p < 0.001). Perceived stability, confidence and reassurance also increased with the ankle taped (p < 0.05) during the stair and two hopping tasks, but not during the SEBT or single-leg stance test.ConclusionAlthough taping the ankle did not affect performance, except to improve stair descent, it increased self-efficacy and perceived confidence in dynamic tasks. These findings suggest that taping may reduce apprehension without affecting functional performance in those with functional ankle instability and permit continued physical activity or sport participation.  相似文献   

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ObjectivesTo investigate the effect of a 6-week stroboscopic balance training program on cortical activities in athletes with chronic ankle instability.DesignRandomized controlled trial. Setting: Single-center.ParticipantsThirty-nine participants were assigned to the strobe group (SG, n = 13), non-strobe group (NSG, n = 13), and control group (CG, n = 13).Main outcome measuresCortical activity and balance velocity were evaluated while the athletes were on the HUBER balance device. Electroencephalographic measurements of cortical activity were made at the transition from bipedal stance to single-leg stance.ResultsThe SG showed significant increases in Cz theta and alpha values and COP-v (center of pressure velocity) between pretest and posttest (p < 0.001, p = 0.003, p < 0.001). Posttest Cz theta was significantly higher in the SG compared to the CG (p = 0.009) and posttest Cz alpha was significantly higher in the SG compared to the NSG (p = 0.039) and CG (p = 0.001). Posttest COP-v was significantly higher in the SG than in the CG (p = 0.031) and NSG (p = 0.03).ConclusionsStroboscopic training may be clinically beneficial to improve balance parameters in athletes with CAI, and may have utility in sport-specific activity phases of rehabilitation to reduce visual input and increase motor control.  相似文献   

19.
ObjectivesThis study aimed to clarify the kinematic, kinetic characteristics associated with lateral ankle sprain.DesignA 16-month prospective cohort study.SettingLaboratory.ParticipantsA total of 179 college athletes.Main outcome measuresJoint kinematics, moment during single-leg landing tasks, and ankle laxity were measured. The attendance of each participating team, injury mechanism, existence of body contact, presence of orthosis, with or without medical diagnosis, and periods of absence were recorded.ResultsTwenty-nine participants incurred lateral ankle sprain during non-contact motion. The Cox regression analysis revealed that greater knee varus peak angle (hazard ratio: 1.16 [95% confidence interval: 1.10–1.22], p < 0.001) and greater pelvic internal rotation peak angle toward the support leg were associated with lateral ankle sprain (hazard ratio: 1.08 [95% confidence interval: 1.02–1.15], p = 0.009). The cut-off values for each predictive factor were −0.17° (area under the curve = 0.89, p < 0.001) and 6.63° (area under the curve = 0.74, p < 0.001), respectively.ConclusionsA greater knee varus peak angle and pelvic internal rotation peak angle after single-leg landing are predictive factors for lateral ankle sprain.  相似文献   

20.
BackgroundImpaired ankle inversion movement discrimination (AIMD) can lead to ankle sprain injuries. The aim of this study was to explore whether wearing textured insoles improved AIMD compared with barefoot, ballet shoes and smooth insoles, among dancers.MethodsForty-four adolescent male and female dancers, aged 13–19, from The Australian Ballet School were tested for AIMD while barefoot, wearing ballet shoes, smooth insoles, and textured insoles.ResultsNo interaction was found between the four different footwear conditions, the two genders, or the two levels of dancers in AIMD (p > .05). An interaction was found between the four different footwear conditions and the three tertiles when tested in ballet shoes (p = .006). Although significant differences were found between the upper tertiles and the lower tertiles when tested with ballet shoes, barefoot and with smooth insoles (p < .001; p < .001; p = .047, respectively), when testing with textured insoles dancers in the lower tertile obtained similar scores to those obtained by dancers in the upper tertile (p = .911).ConclusionTextured insoles improved the discrimination scores of dancers with low AIMD, suggesting that textured insoles may trigger the cutaneous receptors in the plantar surface, increasing the awareness of ankle positioning, which in turn might decrease the chance of ankle injury.  相似文献   

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