Evaluation of the Anterior Cruciate Ligament Injury Risk During a Jump-Landing Task Using 3-Dimensional Kinematic Analysis Versus the Landing Error Scoring System.

Background: The Landing Error Scoring System (LESS) has been utilized on the field or in the clinic to identify patients with an increased risk for anterior cruciate ligament (ACL) injuries; however, its validity and efficacy have not been fully confirmed. Purpose: To assess the efficacy of the LESS in identifying the ACL injury risk by examining the correlation between the LESS score and motion patterns on 3-dimensional kinematic analysis. Study Design: Controlled laboratory study. Methods: The jump-landing motion was analyzed for 16 female basketball or badminton players who volunteered to participate in the study. All study participants were aged 19 or 20 years. The sequence of motion was evaluated with the LESS, while kinematic data were simultaneously acquired with a 3-dimensional motion analysis system utilizing the point cluster method. The correlation between the LESS score and knee kinematics was statistically analyzed. Results: When a LESS score ≥6 was defined to be a risk factor for ACL injuries, 7 of the 16 participants (43.8%) were found to exhibit risky motion patterns. Significant correlations were noted between the LESS score and knee valgus (r = 0.87; P < .0001) and internal tibial rotation (r = 0.57; P = .02) at landing. By contrast, a substantial variability was present in knee flexion, showing no correlation with the LESS score. Conclusion: Significant correlations were found between the LESS score and knee valgus and internal tibial rotation during a jump-landing task. Clinical Relevance: The LESS can be regarded as an effective measure to identify risky motion patterns that may increase the likelihood of ACL injuries.

Kinematics, Kinetics and Muscle Activity Analysis during Single-leg Drop-jump Landing Followed by an Unanticipated Task: Focusing on Differences in Neurocognitive Function.

Background: Lower neurocognitive function is a risk factor for anterior cruciate ligament (ACL) injury. However, the mechanism by which lower neurocognitive function increases the risk of ACL injury remains unclear. Purpose: To clarify the effect of differences in neurocognitive function on landing mechanics during a single-leg drop-jump landing motion followed by an unanticipated task. Study Design: Cross-sectional study. Methods: Fifteen collegiate female athletes were recruited (20.1 ± 1.3 years, 166.6 ± 7.3 cm, 60.6 ± 6.9 kg) and were divided into two groups (the high-performance (HP) group and the lower-performance (LP) group) using the median Symbol Digit Modalities Test (SDMT) score. Three-dimensional motion analysis was employed for the analysis during the experimental task of a single-leg drop-jump followed by an unanticipated landing task from a 30-cm high box. Joint angular changes of the trunk, pelvis, hip, and knee were calculated within the interval from initial contact (IC) to 40ms. Knee and hip moments were calculated as the maximum values within the interval from IC to 40ms. Surface electromyography data from key muscles were analyzed 50ms before and after IC. Independent t-tests were used to compare the effects of different neurocognitive function on the measurement items. Statistical significance was set at p < 0.05. Results: The SDMT score was significantly higher in HP group (HP: 77.9 ± 5.5; LP: 66.0 ± 3.4; p < 0.001). The LP group had a significantly greater trunk rotation angular change to the stance leg side (HP: 0.4 ± 0.8; LP: 1.2 ± 0.4; p = 0.020). There were no significant differences between the two groups in terms of joint moments, and muscle activities. Conclusion: Differences in neurocognitive function by SDMT were found to be related to differences in motor strategies of the trunk in the horizontal plane. Although trunk motion in the sagittal and frontal planes during single-leg drop-jump landing increases the ACL injury risk by affecting knee joint motion, the effect of trunk motion in the horizontal plane remains unclear. Level of Evidence: 3© The Authors.

Effects of Lower-limb Muscle Fatigue, Cardiopulmonary Fatigue, and Brain FatigueTasks on One-legged Landing Motion.

OBJECTIVE: Anterior cruciate ligament (ACL) injury is one of the most frequent sportsinjuries, and previous studies have shown that fatigue is a risk factor for sports injuries.This study aimed to inform prevention of ACL injury by investigating how exercise and desk tasks affect trunk and lower limb alignment and ground reaction force (GRF) during one-legged landing movements. METHODS: The study subjects were 12 men who performed a one-legged landing movement from a 30-cm platform before and after fatigue tasks, including lower-limb muscle fatigue, cardiopulmonary fatigue, and brain fatigue tasks. For the measurement of joint angles and moments and GRF, a three-dimensional motion analysis device and a floor reaction-force meter were used. Statistics were performed using Wilcoxon's signed rank sum test as a multiple comparison test with Bonferroni adjustment to compare the difference in effects. RESULTS: The maximum trunk flexion angle during landing on one leg was significantly lower in the brain fatigue group than in the control group. The time to peak vertical GRF (pGRF) was significantly shorter in the leg-muscle fatigue group than in the control group. CONCLUSION: Brain fatigue may have altered the postural strategy before and after landing, resulting in a decrease in trunk flexion angle. Time to pVGRF was shortened in the leg muscle fatigue group, suggesting that there may be an increased risk of ACL injury. Time to pVGRF during lower extremity muscle fatigue and trunk flexion angle during brain fatigue may be more pronounced during actual sports activities.

The effect of hip abductions muscle strength on knee alignment during a single-leg landing in female basketball players / 体力科学

<p>Non-contact anterior cruciate ligament (ACL) injury is one of the most severe knee problems for female athletes. Several studies have reported that the decreased lower limb control of women such as decrease of hip abductions muscle strength increase the risk of ACL injury. Also ACL Injury often occurs as a result of knee valgus collapse during single leg landing or pivoting in sports activities like basketball. Female basketball players often show an excessive knee valgus and hip adduction during the play. The purpose of this study was to analyze the effect of hip abductions muscle strength on knee alignment during a single leg landing. Thirty healthy female basketball players participated in this study. Mean age, height, body weight and plyer career were 17.3 years old±3.7, 162.7cm±17.2, 56.2kg±10.9, 8.9 years±3.8 respectively. All subjects were obtained written consent from after explanation of the procedure. Significant negative correlations showed that greater hip abductor peak torque (hip flexion 0 and 30degrees) exhibited less motion toward the knee valgus direction during single leg landing. And also, dynamic Trendelenburg test showed that all positive reactions cause knee valgus direction. These results suggest keeping proper knee position safety during single leg landing; female basketball player should improve the hip abductions muscle strength. Hip joint control will be a major issue for prevention of the non-contact ACL injury.</p>

Gender differences in kinematics during landing motion and effect of the prevention program for lower extremity injuries on kinematics in junior basketball players / 体力科学

Anterior Cruciate Ligament Injury often occurs as a result of knee valgus collapse during landing or pivoting in sports activity. Previous studies reported that the risk of ACL injuries was reduced by jump and balance training, and those training can be effective as the prevention program for the ACL injuries. But those studies often focused on only adult athletes, and there are few studies focused on junior athletes. The purpose of this study is to investigate the pattern of landing movement in junior athletes, and to verify the effect of the prevention program. One-hundred and ten junior basketball players (boys; 61, girls;49, age ranging 12 to 15) were subjected in this study. We measured the knee flexion, valgus angles and jump height during continuous vertical jump. After measuring, they executed a prevention program for 12 weeks. The motion pattern of the knee during jump test were compaired between before and after prevention program. Female athletes showed greater knee valgus angle at initial landing phase and grater maximum knee valgus angle than those of males. As a result of the prevention program, maximum knee valgus angle was significantly decreased in female athletes. The greater angle of knee valgus in female may increase the risk of ACL injuries. Present study suggests that the prevention program is useful for reducing the risk of ACL injury. Increment of jump height in male players after this program might be considered that this training program has also an effect of performance improvement.

Effects of landing motion on power during takeoff in rebound drop jump. With special reference to angle at the knee joint / 体力科学

This study clarified the most appropriate landing motion for enhancement of the rebound drop jump index (RDJ<SUB>index</SUB>), which can evaluate the ability to perform ballistic and stretch-shortening cycle (SSC) movements. The RDJindex was calculated using the formula RDJ<SUB>index</SUB>= (1/8⋅g⋅RDJt<SUB>a</SUB><SUP>2</SUP>) /RDJt<SUB>c</SUB> where RDJt<SUB>c</SUB> and RDJt<SUB>a</SUB> are the contact and air times during a rebound drop jump from a height of 0.3 m (RDJ), a typical SSC movement. The relationships between the RDJ<SUB>index</SUB> and the characteristics of the knee and ankle joint motions during RDJ were examined in nine male jumpers. The results were as follows:<BR>(1) The characteristics of leg motion during the descending phase were that the ratio (%K-ANG) of displacement in flexion of the knee during the descending phase to that during both descending and takeoff phases was 48.6% and this preliminary motion started 53.6 ms before touchdown. Furthermore, as %K-ANG increaced, the contact time decreased (r=-0.784, p<0.05), the air time increased (r=0.874, p<0.01) and consequently, the RDJ<SUB>index</SUB> increased (r=0.891, p<0.01) . These results suggested that quick knee flexion just before touchdown is an important factor in increasing the RDJ<SUB>index</SUB>.<BR>(2) A characteristic of the leg motion during the takeoff phase was that the end point of knee flexion appeared 13.3 ms earlier than that of ankle dorsiflexion. That time increased as %K-ANG increaced (r=0.830, p<0.01), but conversely, as %K-ANG decreased markedly, end point of ankle dorsiflexion appeared earlier than that of knee flexion. These results suggested that preliminary motion of the knee would result in appropriate timing of the knee and ankle motions for shock absorption during the takeoff phase of RDJ.<BR>(3) An other characteristic of the leg motion during the takeoff phase was that the ratio of displacement of the knee in extension to that in flexion was 310.2%. This ratio increased as %K-ANG increaced (r=0.903, p<0.001) . These results suggested that preliminary motion of the knee would cause to increase displacement in extension for kick motion and yet to decrease displacement in flexion for shock absorption.<BR>These findings led to the conclusion that quick and short range flexion at the knee just before touchdown was an effective landing motion for enhancing the ability to perform ballistic and SSC movements.

Lower extremity function for shock attenuation during landing on one leg / 体力科学

A study was conducted to investigate the cushioning effects of lower extremity functions on shock attenuation during landing on one leg.<BR>Optical methods were used to investigate the cushioning effects of lower extremity functions, since these facilitated the quantitation of kinematic variables such as angle, change in angle, position, displacement and velocity during the landing. The subjects were 5 healthy students ranging in age from 21 to 24 years. Ground reaction force (GRF) was measured with a force platform. The impact force peaks showed vertical force-time averages for 1 subject landing on one leg or two legs for 10 trials each from a height of 10cm.<BR>The peak/body weight of impact force of GRF upon landing was attenuated by the cushioning effects of the lower extremity functions, i. e. bending of the knee and ankle joints, more effectively on two legs than on one.<BR>Supination and pronation of the ankle joint influenced the impact force peaks, and the results of this experiment demonstrated significant difference between the number of discharge bursts of leg muscles upon landing on one leg and those landing on two, the former being higher.