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THE INFLUENCE OF HIP MUSCLE PERFORMANCE ON THE INFLUENCE OF HIP MUSCLE PERFORMANCE ON THE INFLUENCE OF HIP MUSCLE PERFORMANCE ON THE INFLUENCE OF HIP MUSCLE PERFORMANCE ON THE INFLUENCE OF HIP MUSCLE PERFORMANCE ON THE INFLUENCE OF HIP MUSCLE PERFORMANCE ON THE INFLUENCE OF HIP MUSCLE PERFORMANCE ON THE INFLUENCE OF HIP MUSCLE PERFORMANCE ON THE INFLUENCE OF HIP MUSCLE PERFORMANCE ON THE INFLUENCE OF HIP MUSCLE PERFORMANCE ON THE INFLUENCE OF HIP MUSCLE PERFORMANCE ON THE INFLUENCE OF HIP MUSCLE PERFORMANCE ON THE INFLUENCE OF HIP MUSCLE PERFORMANCE ON THE INFLUENCE OF HIP MUSCLE PERFORMANCE ON THE INFLUENCE OF HIP MUSCLE PERFORMANCE ON THE INFLUENCE OF HIP MUSCLE PERFORMANCE ON THE INFLUENCE OF HIP MUSCLE PERFORMANCE ON THE INFLUENCE OF HIP MUSCLE PERFORMANCE ON THE INFLUENCE OF HIP MUSCLE PERFORMANCE ON THE INFLUENCE OF HIP MUSCLE PERFORMANCE ON THE INFLUENCE OF HIP MUSCLE PERFORMANCE ON THE INFLUENCE OF HIP MUSCLE PERFORMANCE ON THE INFLUENCE OF HIP MUSCLE PERFORMANCE ON THE INFLUENCE OF HIP MUSCLE PERFORMANCE ON LOWER LOWER LOWER EXT REMITY BIOMECHANICSMITY BIOMECHANICSMITY BIOMECHANICS MITY BIOMECHANICSMITY BIOMECHANICSMITY BIOMECHANICSMITY BIOMECHANICS MITY BIOMECHANICS MITY BIOMECHANICSMITY BIOMECHANICSMITY BIOMECHANICSMITY BIOMECHANICS AND NEUROMU NEUROMUNEUROMUNEUROMU SCULAR SCULAR SCULAR SCULAR SCULAR ACTIVATION ACTIVATIONACTIVATIONACTIVATIONACTIVATIONACTIVATIONACTIVATIONACTIVATION: IMPLICATIONS FOR ANTERIOR CRUCIATE LIGAMENT INJURY IMPLICATIONS FOR ANTERIOR CRUCIATE LIGAMENT INJURY IMPLICATIONS FOR ANTERIOR CRUCIATE LIGAMENT INJURY IMPLICATIONS FOR ANTERIOR CRUCIATE LIGAMENT INJURY IMPLICATIONS FOR ANTERIOR CRUCIATE LIGAMENT INJURY IMPLICATIONS FOR ANTERIOR CRUCIATE LIGAMENT INJURY IMPLICATIONS FOR ANTERIOR CRUCIATE LIGAMENT INJURY IMPLICATIONS FOR ANTERIOR CRUCIATE LIGAMENT INJURY IMPLICATIONS FOR ANTERIOR CRUCIATE LIGAMENT INJURY IMPLICATIONS FOR ANTERIOR CRUCIATE LIGAMENT INJURY IMPLICATIONS FOR ANTERIOR CRUCIATE LIGAMENT INJURY IMPLICATIONS FOR ANTERIOR CRUCIATE LIGAMENT INJURY IMPLICATIONS FOR ANTERIOR CRUCIATE LIGAMENT INJURY IMPLICATIONS FOR ANTERIOR CRUCIATE LIGAMENT INJURY IMPLICATIONS FOR ANTERIOR CRUCIATE LIGAMENT INJURY IMPLICATIONS FOR ANTERIOR CRUCIATE LIGAMENT INJURY IMPLICATIONS FOR ANTERIOR CRUCIATE LIGAMENT INJURY IMPLICATIONS FOR ANTERIOR CRUCIATE LIGAMENT INJURY IMPLICATIONS FOR ANTERIOR CRUCIATE LIGAMENT INJURY IMPLICATIONS FOR ANTERIOR CRUCIATE LIGAMENT INJURY IMPLICATIONS FOR ANTERIOR CRUCIATE LIGAMENT INJURY IMPLICATIONS FOR ANTERIOR CRUCIATE LIGAMENT INJURY IMPLICATIONS FOR ANTERIOR CRUCIATE LIGAMENT INJURY IMPLICATIONS FOR ANTERIOR CRUCIATE LIGAMENT INJURY IMPLICATIONS FOR ANTERIOR CRUCIATE LIGAMENT INJURY IMPLICATIONS FOR ANTERIOR CRUCIATE LIGAMENT INJURY IMPLICATIONS FOR ANTERIOR CRUCIATE LIGAMENT INJURY IMPLICATIONS FOR ANTERIOR CRUCIATE LIGAMENT INJURY IMPLICATIONS FOR ANTERIOR CRUCIATE LIGAMENT INJURY IMPLICATIONS FOR ANTERIOR CRUCIATE LIGAMENT INJURY IMPLICATIONS FOR ANTERIOR CRUCIATE LIGAMENT INJURY
by
Kristen M. Stearns Kristen M. Stearns Kristen M. StearnsKristen M. Stearns Kristen M. Stearns Kristen M. Stearns
A Dissertation Presented to theA Dissertation Presented to the A Dissertation Presented to the A Dissertation Presented to the A Dissertation Presented to theA Dissertation Presented to theA Dissertation Presented to the A Dissertation Presented to the A Dissertation Presented to the
FACULTY OF THE USC GRADUATE SFACULTY OF THE USC GRADUATE S FACULTY OF THE USC GRADUATE SFACULTY OF THE USC GRADUATE SFACULTY OF THE USC GRADUATE SFACULTY OF THE USC GRADUATE S FACULTY OF THE USC GRADUATE SFACULTY OF THE USC GRADUATE SFACULTY OF THE USC GRADUATE S FACULTY OF THE USC GRADUATE SFACULTY OF THE USC GRADUATE S FACULTY OF THE USC GRADUATE S FACULTY OF THE USC GRADUATE S FACULTY OF THE USC GRADUATE S CHOOLCHOOL CHOOLCHOOL
UNIVERSITY OF SOUTHERN CALIFORNIA UNIVERSITY OF SOUTHERN CALIFORNIAUNIVERSITY OF SOUTHERN CALIFORNIA UNIVERSITY OF SOUTHERN CALIFORNIAUNIVERSITY OF SOUTHERN CALIFORNIA UNIVERSITY OF SOUTHERN CALIFORNIAUNIVERSITY OF SOUTHERN CALIFORNIA UNIVERSITY OF SOUTHERN CALIFORNIA UNIVERSITY OF SOUTHERN CALIFORNIA UNIVERSITY OF SOUTHERN CALIFORNIA UNIVERSITY OF SOUTHERN CALIFORNIAUNIVERSITY OF SOUTHERN CALIFORNIA UNIVERSITY OF SOUTHERN CALIFORNIA UNIVERSITY OF SOUTHERN CALIFORNIAUNIVERSITY OF SOUTHERN CALIFORNIA UNIVERSITY OF SOUTHERN CALIFORNIAUNIVERSITY OF SOUTHERN CALIFORNIA
In Partial Fulfillment of theIn Partial Fulfillment of the In Partial Fulfillment of theIn Partial Fulfillment of the In Partial Fulfillment of the In Partial Fulfillment of the In Partial Fulfillment of the
Requirements for the DegreeRequirements for the DegreeRequirements for the Degree Requirements for the Degree Requirements for the Degree Requirements for the DegreeRequirements for the DegreeRequirements for the DegreeRequirements for the DegreeRequirements for the Degree
DOCTOR OF PHILOSOPHY DOCTOR OF PHILOSOPHYDOCTOR OF PHILOSOPHYDOCTOR OF PHILOSOPHY DOCTOR OF PHILOSOPHY DOCTOR OF PHILOSOPHYDOCTOR OF PHILOSOPHY DOCTOR OF PHILOSOPHY DOCTOR OF PHILOSOPHYDOCTOR OF PHILOSOPHYDOCTOR OF PHILOSOPHY
(BIOKINESIOLOGY) (BIOKINESIOLOGY)(BIOKINESIOLOGY)(BIOKINESIOLOGY)(BIOKINESIOLOGY) (BIOKINESIOLOGY)(BIOKINESIOLOGY)(BIOKINESIOLOGY)(BIOKINESIOLOGY) (BIOKINESIOLOGY)(BIOKINESIOLOGY)
August August 201 2
Copyright 2012
Kristen M. Stearns
Object Description
| Title | The influence of hip muscle performance on lower extremity biomechanics and neuromuscular activation: implications for anterior cruciate ligament injury |
| Author | Stearns, Kristen M. |
| Author email | kristen.stearns@gmail.com;kristen.stearns@gmail.com |
| Degree | Doctor of Philosophy |
| Document type | Dissertation |
| Degree program | Biokinesiology |
| School | School of Dentistry |
| Date defended/completed | 2012-08-01 |
| Date submitted | 2012-08-01 |
| Date approved | 2012-08-01 |
| Restricted until | 2012-08-01 |
| Date published | 2012-08-01 |
| Advisor (committee chair) | Powers, Christopher M. |
| Advisor (committee member) |
Gordon, James Baker, Lucinda Keim, Robert Pollard, Christine D. |
| Abstract | While the higher rates of ACL injury observed in females have been attributed to sex differences in lower extremity biomechanics and neuromuscular activation during sports specific maneuvers, the factors that underlie this movement behavior remain unknown. Deficits in hip muscle performance have been suggested to contribute to the “at risk” biomechanics observed in females; however no studies have systematically evaluated sex differences in hip muscle performance in relation to these biomechanical and neuromuscular factors. The specific aims of this dissertation were developed to better understand the influence of hip extensor muscle performance on lower extremity biomechanics and neuromuscular activation. ❧ The purpose of Chapter III was to test the hypothesis that sex differences in hip extensor maximal isometric strength influence lower extremity biomechanics during a drop-jump task. Forty-one recreationally active individuals participated in this study (20 males, 21 females). Maximum isometric strength of the knee extensors and hip extensors and lower extremity kinematics and kinetics during a double-leg drop-jump task were assessed. A significant correlation between the knee/hip extensor strength ratio and the knee/hip extensor moment ratio was observed. This result suggests that the tendency of females to exhibit higher knee extensor moments relative to hip extensor moments may be explained, in part, by relative weakness of the hip extensors, compared to the knee extensors. ❧ The purpose of Chapter IV was to test the hypothesis that females would demonstrate deficits in rate of torque development (RTD) of the hip and knee extensors when compared to males, and these deficits would be accompanied by sex differences in activation of the vastus lateralis (VL) and gluteus maximus (GMAX) during landing. Twenty male and twenty-one female recreational athletes underwent RTD testing of the knee and hip extensors. Surface EMG was used to assess onset timing of the VL and GMAX prior to initial contact during a drop jump task. Results revealed that while females were unable to generate torque as rapidly as males with both their hip and knee extensors, deficits in hip extensor RTD were more pronounced in females. In addition, females demonstrated a significantly earlier onset of both the VL and GMAX when compared to males. Interestingly, the onset time of the VL was much earlier than that of the GMAX. The earlier EMG onset time of the VL and GMAX observed prior to ground contact in females is suggestive of a feed-forward strategy by which females attempt to compensate for their inability to rapidly generate muscle torque. ❧ The purpose of Chapter V was to investigate the influence of a hip-focused training program on lower extremity biomechanics and the neuromuscular activation strategy during a drop-jump task. Twenty-one recreationally active females participated in a 4-week training program (3 times/week, 30 min/session) consisting of hip-focused plyometric and balance perturbation exercises. Muscle performance testing of the hip and knee extensors, as well as biomechanical and neuromuscular evaluation during a drop-jump task was performed before and after completion of the training program. Following training, females demonstrated increased RTD and maximum isometric strength of the hip extensors. In addition, improvements in knee and hip joint biomechanics and a later onset time of the VL and GMAX were observed. As no significant improvements in knee extensor muscle performance were observed, changes in lower extremity biomechanics and neuromuscular activation following training appear to be driven by increases in hip extensor muscle performance. These results suggest that training programs that target hip extensor muscle performance may be important in mitigating biomechanical and neuromuscular risk factors associated with ACL injury in females. ❧ Taken together the results of this dissertation indicate that diminished hip muscle performance may underlie the “at risk” biomechanical and neuromuscular strategy observed in females that is thought to be associated with an increased risk for ACL injury. In particular, diminished hip muscle performance in females resulted in compensatory utilization of the quadriceps. Furthermore, a hip-focused training program resulted in greater utilization of the hip extensors and decreased reliance on the knee extensors during landing. Results from this study have important implications for training programs aimed at reducing ACL injury risk. |
| Keyword | hip muscle performance; lower extremity; biomechanics; sex differences; activation; training |
| Language | English |
| Part of collection | University of Southern California dissertations and theses |
| Publisher (of the original version) | University of Southern California |
| Place of publication (of the original version) | Los Angeles, California |
| Publisher (of the digital version) | University of Southern California. Libraries |
| Provenance | Electronically uploaded by the author |
| Type | texts |
| Legacy record ID | usctheses-m |
| Rights | Stearns, Kristen M. |
| Access conditions | The author retains rights to his/her dissertation, thesis or other graduate work according to U.S. copyright law. Electronic access is being provided by the USC Libraries in agreement with the author, as the original true and official version of the work, but does not grant the reader permission to use the work if the desired use is covered by copyright. It is the author, as rights holder, who must provide use permission if such use is covered by copyright. The original signature page accompanying the original submission of the work to the USC Libraries is retained by the USC Libraries and a copy of it may be obtained by authorized requesters contacting the repository e-mail address given. |
| Repository name | University of Southern California Digital Library |
| Repository address | USC Digital Library, University of Southern California, University Park Campus MC 7002, 106 University Village, Los Angeles, California 90089-7002, USA |
| Repository email | cisadmin@usc.edu |
| Archival file | uscthesesreloadpub_Volume4/etd-StearnsKri-1101.pdf |
Description
| Title | Page 1 |
| Full text | THE INFLUENCE OF HIP MUSCLE PERFORMANCE ON THE INFLUENCE OF HIP MUSCLE PERFORMANCE ON THE INFLUENCE OF HIP MUSCLE PERFORMANCE ON THE INFLUENCE OF HIP MUSCLE PERFORMANCE ON THE INFLUENCE OF HIP MUSCLE PERFORMANCE ON THE INFLUENCE OF HIP MUSCLE PERFORMANCE ON THE INFLUENCE OF HIP MUSCLE PERFORMANCE ON THE INFLUENCE OF HIP MUSCLE PERFORMANCE ON THE INFLUENCE OF HIP MUSCLE PERFORMANCE ON THE INFLUENCE OF HIP MUSCLE PERFORMANCE ON THE INFLUENCE OF HIP MUSCLE PERFORMANCE ON THE INFLUENCE OF HIP MUSCLE PERFORMANCE ON THE INFLUENCE OF HIP MUSCLE PERFORMANCE ON THE INFLUENCE OF HIP MUSCLE PERFORMANCE ON THE INFLUENCE OF HIP MUSCLE PERFORMANCE ON THE INFLUENCE OF HIP MUSCLE PERFORMANCE ON THE INFLUENCE OF HIP MUSCLE PERFORMANCE ON THE INFLUENCE OF HIP MUSCLE PERFORMANCE ON THE INFLUENCE OF HIP MUSCLE PERFORMANCE ON THE INFLUENCE OF HIP MUSCLE PERFORMANCE ON THE INFLUENCE OF HIP MUSCLE PERFORMANCE ON THE INFLUENCE OF HIP MUSCLE PERFORMANCE ON THE INFLUENCE OF HIP MUSCLE PERFORMANCE ON THE INFLUENCE OF HIP MUSCLE PERFORMANCE ON LOWER LOWER LOWER EXT REMITY BIOMECHANICSMITY BIOMECHANICSMITY BIOMECHANICS MITY BIOMECHANICSMITY BIOMECHANICSMITY BIOMECHANICSMITY BIOMECHANICS MITY BIOMECHANICS MITY BIOMECHANICSMITY BIOMECHANICSMITY BIOMECHANICSMITY BIOMECHANICS AND NEUROMU NEUROMUNEUROMUNEUROMU SCULAR SCULAR SCULAR SCULAR SCULAR ACTIVATION ACTIVATIONACTIVATIONACTIVATIONACTIVATIONACTIVATIONACTIVATIONACTIVATION: IMPLICATIONS FOR ANTERIOR CRUCIATE LIGAMENT INJURY IMPLICATIONS FOR ANTERIOR CRUCIATE LIGAMENT INJURY IMPLICATIONS FOR ANTERIOR CRUCIATE LIGAMENT INJURY IMPLICATIONS FOR ANTERIOR CRUCIATE LIGAMENT INJURY IMPLICATIONS FOR ANTERIOR CRUCIATE LIGAMENT INJURY IMPLICATIONS FOR ANTERIOR CRUCIATE LIGAMENT INJURY IMPLICATIONS FOR ANTERIOR CRUCIATE LIGAMENT INJURY IMPLICATIONS FOR ANTERIOR CRUCIATE LIGAMENT INJURY IMPLICATIONS FOR ANTERIOR CRUCIATE LIGAMENT INJURY IMPLICATIONS FOR ANTERIOR CRUCIATE LIGAMENT INJURY IMPLICATIONS FOR ANTERIOR CRUCIATE LIGAMENT INJURY IMPLICATIONS FOR ANTERIOR CRUCIATE LIGAMENT INJURY IMPLICATIONS FOR ANTERIOR CRUCIATE LIGAMENT INJURY IMPLICATIONS FOR ANTERIOR CRUCIATE LIGAMENT INJURY IMPLICATIONS FOR ANTERIOR CRUCIATE LIGAMENT INJURY IMPLICATIONS FOR ANTERIOR CRUCIATE LIGAMENT INJURY IMPLICATIONS FOR ANTERIOR CRUCIATE LIGAMENT INJURY IMPLICATIONS FOR ANTERIOR CRUCIATE LIGAMENT INJURY IMPLICATIONS FOR ANTERIOR CRUCIATE LIGAMENT INJURY IMPLICATIONS FOR ANTERIOR CRUCIATE LIGAMENT INJURY IMPLICATIONS FOR ANTERIOR CRUCIATE LIGAMENT INJURY IMPLICATIONS FOR ANTERIOR CRUCIATE LIGAMENT INJURY IMPLICATIONS FOR ANTERIOR CRUCIATE LIGAMENT INJURY IMPLICATIONS FOR ANTERIOR CRUCIATE LIGAMENT INJURY IMPLICATIONS FOR ANTERIOR CRUCIATE LIGAMENT INJURY IMPLICATIONS FOR ANTERIOR CRUCIATE LIGAMENT INJURY IMPLICATIONS FOR ANTERIOR CRUCIATE LIGAMENT INJURY IMPLICATIONS FOR ANTERIOR CRUCIATE LIGAMENT INJURY IMPLICATIONS FOR ANTERIOR CRUCIATE LIGAMENT INJURY IMPLICATIONS FOR ANTERIOR CRUCIATE LIGAMENT INJURY IMPLICATIONS FOR ANTERIOR CRUCIATE LIGAMENT INJURY by Kristen M. Stearns Kristen M. Stearns Kristen M. StearnsKristen M. Stearns Kristen M. Stearns Kristen M. Stearns A Dissertation Presented to theA Dissertation Presented to the A Dissertation Presented to the A Dissertation Presented to the A Dissertation Presented to theA Dissertation Presented to theA Dissertation Presented to the A Dissertation Presented to the A Dissertation Presented to the FACULTY OF THE USC GRADUATE SFACULTY OF THE USC GRADUATE S FACULTY OF THE USC GRADUATE SFACULTY OF THE USC GRADUATE SFACULTY OF THE USC GRADUATE SFACULTY OF THE USC GRADUATE S FACULTY OF THE USC GRADUATE SFACULTY OF THE USC GRADUATE SFACULTY OF THE USC GRADUATE S FACULTY OF THE USC GRADUATE SFACULTY OF THE USC GRADUATE S FACULTY OF THE USC GRADUATE S FACULTY OF THE USC GRADUATE S FACULTY OF THE USC GRADUATE S CHOOLCHOOL CHOOLCHOOL UNIVERSITY OF SOUTHERN CALIFORNIA UNIVERSITY OF SOUTHERN CALIFORNIAUNIVERSITY OF SOUTHERN CALIFORNIA UNIVERSITY OF SOUTHERN CALIFORNIAUNIVERSITY OF SOUTHERN CALIFORNIA UNIVERSITY OF SOUTHERN CALIFORNIAUNIVERSITY OF SOUTHERN CALIFORNIA UNIVERSITY OF SOUTHERN CALIFORNIA UNIVERSITY OF SOUTHERN CALIFORNIA UNIVERSITY OF SOUTHERN CALIFORNIA UNIVERSITY OF SOUTHERN CALIFORNIAUNIVERSITY OF SOUTHERN CALIFORNIA UNIVERSITY OF SOUTHERN CALIFORNIA UNIVERSITY OF SOUTHERN CALIFORNIAUNIVERSITY OF SOUTHERN CALIFORNIA UNIVERSITY OF SOUTHERN CALIFORNIAUNIVERSITY OF SOUTHERN CALIFORNIA In Partial Fulfillment of theIn Partial Fulfillment of the In Partial Fulfillment of theIn Partial Fulfillment of the In Partial Fulfillment of the In Partial Fulfillment of the In Partial Fulfillment of the Requirements for the DegreeRequirements for the DegreeRequirements for the Degree Requirements for the Degree Requirements for the Degree Requirements for the DegreeRequirements for the DegreeRequirements for the DegreeRequirements for the DegreeRequirements for the Degree DOCTOR OF PHILOSOPHY DOCTOR OF PHILOSOPHYDOCTOR OF PHILOSOPHYDOCTOR OF PHILOSOPHY DOCTOR OF PHILOSOPHY DOCTOR OF PHILOSOPHYDOCTOR OF PHILOSOPHY DOCTOR OF PHILOSOPHY DOCTOR OF PHILOSOPHYDOCTOR OF PHILOSOPHYDOCTOR OF PHILOSOPHY (BIOKINESIOLOGY) (BIOKINESIOLOGY)(BIOKINESIOLOGY)(BIOKINESIOLOGY)(BIOKINESIOLOGY) (BIOKINESIOLOGY)(BIOKINESIOLOGY)(BIOKINESIOLOGY)(BIOKINESIOLOGY) (BIOKINESIOLOGY)(BIOKINESIOLOGY) August August 201 2 Copyright 2012 Kristen M. Stearns |
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