Biomechanics of the Lower Extremity During a Single Leg Drop Landing PDF Download
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Author: Lori L. Webster-Dahl
Publisher:
ISBN:
Category : Ground reaction force (Biomechanics)
Languages : en
Pages : 74
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Author: Lori L. Webster-Dahl
Publisher:
ISBN:
Category : Ground reaction force (Biomechanics)
Languages : en
Pages : 74
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Author: Stacey L. Gaven
Publisher:
ISBN:
Category : Biomechanics
Languages : en
Pages : 274
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Author: Derek J. Eversley
Publisher:
ISBN:
Category : Anterior cruciate ligament
Languages : en
Pages : 96
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Author: Allen L. Redinger
Publisher:
ISBN:
Category : Impact
Languages : en
Pages : 63
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Lower extremity musculoskeletal injuries are a common occurrence that can threaten deployment, completion of duty, and quality of life for a soldier. Repetitive activities, explosive movements, impact forces, and extreme joint angles all increase risk for injury and are often found in military physical training. Addition of external loading is necessary for combat situations and can lead to biomechanical alterations in gait, landing, and reactive forces, even at small bodyweight-relative loads. Although external load might not be able to be manipulated, individual strength levels and appropriate landing technique may reduce the relative risk for injury. The purpose of this study was to determine how a combat-relative body-borne loads can affect lower extremity biomechanics in Reserve Officers' Training Core cadets utilizing 3D motion capture and in-ground force plate analysis. Twenty-five college-aged Ohio University Reserve Officer's Training Core cadets and military personnel conducted two series of three consecutive jump landings from a 30cm high box placed half their height from the landing position on two force plates. The testing series consisted of an unweighted baseline condition and a weighted condition of 35% of their bodyweight added to their person by the way of a tactical weighted vest. Unloaded baseline and weighted conditions were compared using a paired t-test and 95% confidence intervals (p
Author: Nicholas Romanchuk
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Despite the higher incidence of anterior cruciate ligament injuries in pediatric female populations, limited research has investigated sex-differences in youth biomechanics. Furthermore, research involving jump mechanics typically requires participant to follow a set protocol, such as sticking the landing. To reduce variability and improve reliability, trails where participants fail to meet the required protocol are discarded; however, significant clinical findings may be elucidated from these trials. The purpose of this thesis was to provide a complete biomechanical analysis of unanticipated single-leg drop-jump landings in youth athletes. Thirty-two healthy youth athletes completed unanticipated single-leg drop-jump landings on their dominant limb. Trials where participants shifted foot position or touched the ground with the contralateral leg were categorized as failed. Drop-jump landings were time-normalized using landmarks within the drop-jump task. Statistical parametric mapping (SPM) determined time-varying sex-differences in muscle onset time, co-activation, kinematics and kinetics. Wilcoxon signed-rank tests and paired sample t-tests compared lower-limb kinematics, centre-of-mass excursion and muscle activation amplitudes during the successful and failed landings. A logistic regression model was also fit to predict the likelihood of a successful landing. SPM identified significantly greater trunk flexion angle in males during the deceleration, flight, and landing phase of the drop-jump. Greater quadriceps-gastrocnemius co-activation was identified during the flight phase in female participants and independent sample t-test identified longer muscle onset time in the vastus lateralis of male participants. When comparing failed and successful landings greater hip abduction and less external rotation angles were observed during the successful trials. In addition, greater preparatory muscle activation was observed in the rectus femoris and semitendinosus during the flight phase of the failed landings. A logistic regression model, which included eight kinematic and neuromuscular variables, offered a training classification accuracy of 70% and a leave-one-out cross-validation accuracy of 65%. In conclusion, females land in a more erect posture and may be less effective at dissipating landing forces. In addition, greater co-activation and shorter pre-activations of the lower limb musculature may indicate a less effective muscle activation strategy in females. Furthermore, hip kinematics and the surrounding musculature play an important role in controlling successful and failed unanticipated landings. The variables included in the logistic regression model indicate which key factors are linked to landing a jump successfully. Training modalities aimed at improving landing mechanics should therefore focus on modifying these variables.
Author: Michael Hoff
Publisher:
ISBN:
Category :
Languages : en
Pages : 63
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Anterior cruciate ligament (ACL) ruptures are a common injury in sports with short and long term consequences. Second ACL injury rates, defined as an injury to the contralateral or healthy limb, or a re-graft tear of the reconstructed ACL, are on the rise and can range from 24-49%. Previous literature suggests that quadriceps strength limb symmetry index (LSI) is a predictor of second ACL injury after returning to sport. Since single leg hop tests have been shown to not be a predictor of future second ACL injuries, using a functional task with systematically increased demands may help identify strength asymmetry thresholds at which ACLR individuals lose the ability to biomechanically adapt and present movement profiles that may increase risk for a second ACL injury. Specific to this thesis project, we hypothesized that: 1) ACL reconstructed (ACLR) individuals with [less-than]90% quadriceps strength LSI would exhibit biomechanical asymmetries regardless of task demands compared to ACLR individuals with 3?90% quadriceps strength LSI and healthy controls. 2) ACLR individuals with 3?90% quadriceps strength LSI would exhibit biomechanical asymmetries but only when task demands are highest compared to healthy controls. The two purposes of this study are to determine: 1) the effects of quadriceps strength symmetry and task demands on lower extremity biomechanics in ACLR and healthy controls, 2) evaluate asymmetries in single leg tasks. Data was collected on 10 healthy controls and 10 ACLR individuals that were all physically active and scored on the Tegner survey. All participants were asked to complete three hopping tasks commonly used in return to sport testing: the single leg hop for distance, the triple leg hop for distance, and the 6- meter timed hop. Quadriceps strength was measured using a dynamometer and the results determined our two ACLR groups: ACLR LSI 3?90% and ACLR LSI [less-than]90%. Participants performed three vertical drop jumps each from box heights of 30cm, 45cm, and 60cm. Additionally, participants performed single leg landing and single leg takeoff hops targeting 75% of their maximum single leg hop distance obtained earlier in the protocol. The ACLR LSI [less-than]90% group displayed biomechanical asymmetries during both the drop jump and single leg hopping tasks. The uninjured limb of the ACLR LSI [less-than]90% group displayed significantly higher knee adduction torques upon initial contact with the forceplate compared to the healthy matched control limbs at 30cm and 60cm heights, and ACLR LSI3?90% uninjured limbs at all three landing heights (p=0.018, observed power=0.81). During the single leg hopping trials, the ACLR LSI [less-than]90% group displayed a reduction in quadriceps efforts in their injured limb vs non-injured limb as demonstrated by reduced knee energy generation (hop landing) and absorption (hop takeoff), while also maintaining similar ground reaction forces during both single leg landing and takeoff trials (p=0.005, observed power= 0.90). The current thesis had several limitations that could have masked the results obtained: 1) the ACLR groups had small sample sizes, 2) the Tegner scale scores were statistically different between groups with the highest level of activity present in the ACLR LSI [less-than]90% group. Overall, ACLR LSI [less-than]90% exhibited movement characteristics in both the double leg drop jumps and single leg hopping tasks that suggest they are at heightened risk for a second ACL injury. Future research efforts should substantiate these findings as well as attempt to explain why these movement compensations occur post- ACL reconstruction.
Author: Michael J. Gale
Publisher:
ISBN:
Category : Ankle
Languages : en
Pages : 84
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Author: Himadri H. Patel
Publisher:
ISBN:
Category : Musculoskeletal system
Languages : en
Pages : 0
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The purpose of this research is to observe the biomechanical response of the leg to singleleg drop landings after a prolonged plantar flexor stretch of 10 min.
Author: Hannah L. Price
Publisher:
ISBN:
Category :
Languages : en
Pages : 70
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Author: Saori Hanaki
Publisher:
ISBN:
Category : Ground reaction force (Biomechanics)
Languages : en
Pages : 94
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