Source:http://linkedlifedata.com/resource/pubmed/id/15473345
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| Predicate | Object |
|---|---|
| rdf:type | |
| lifeskim:mentions | |
| pubmed:issue |
6
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| pubmed:dateCreated |
2004-10-11
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| pubmed:abstractText |
The purpose of this investigation was to determine differences between pre- and post-pubescent males and females in quadriceps (vastus medialis; VM) and hamstrings (medial hamstrings and biceps femoris; HAMS) muscular activation patterns via the root mean square of surface electromyography (SEMG) during self-initiated vertical jump landing. Fifty-eight subjects, divided into age and gender groupings, were compared on kinematic variables during pre-landing (100 msec preceeding initial ground contact), post-landing (100 msec following initial ground contact), and initial-contact-to-maximum-knee-flexion stages. Kinematic variables investigated were (1) SEMG values during each stage of the vertical-jump landing; (2) Co-contraction ratios (CCR), which represented the ratio of normalized hamstrings' activity to normalized quadriceps' activity; and, (3) knee angle at initial contact. Results indicated (1) no significant gender differences in variables measured; and, (2) significant developmental level differences. Post-pubescent subjects displayed greater HAMS acitivity and CCR values in the pre-landing stage relative to post-landing stages, indicating that post-pubescent subjects had a greater level of hamstrings co-contraction prior to landing than pre-pubescent subjects. Conversely, pre-pubescent subjects displayed greater post-landing and initial-contact-to-maximum-knee-flexion ratios, indicating a greater level of hamstrings' co-contraction during post-landing stages than post-pubescent subjects. There were no significant differences in knee angle at initial contact. The greater level of hamstrings' co-activation prior to landing by post-pubescent subjects indicated that they used a strategy of pre-tuning the hamstrings prior to landing (more CNS pre-activation) to control the ground reaction forces and anterior tibial displacement experienced by the knee during landing. On the other hand, pre-pubescent subjects controlled these forces by having a greater level of hamstrings' co-activation during landing, which represents more of a reflexive activation in response to ground impact.
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| pubmed:language |
eng
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| pubmed:journal | |
| pubmed:citationSubset |
IM
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| pubmed:status |
MEDLINE
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| pubmed:month |
Sep
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| pubmed:issn |
0301-150X
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| pubmed:author | |
| pubmed:issnType |
Print
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| pubmed:volume |
44
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| pubmed:owner |
NLM
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| pubmed:authorsComplete |
Y
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| pubmed:pagination |
339-48
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| pubmed:dateRevised |
2006-11-15
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| pubmed:meshHeading |
pubmed-meshheading:15473345-Adult,
pubmed-meshheading:15473345-Age Factors,
pubmed-meshheading:15473345-Child,
pubmed-meshheading:15473345-Electromyography,
pubmed-meshheading:15473345-Female,
pubmed-meshheading:15473345-Humans,
pubmed-meshheading:15473345-Knee Joint,
pubmed-meshheading:15473345-Male,
pubmed-meshheading:15473345-Motor Activity,
pubmed-meshheading:15473345-Muscle, Skeletal,
pubmed-meshheading:15473345-Reflex,
pubmed-meshheading:15473345-Sex Factors
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| pubmed:year |
2004
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| pubmed:articleTitle |
Knee muscular response strategies differ by developmental level but not gender during jump landing.
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| pubmed:affiliation |
University of New Hampshire's Applied Biomechanics and Motor Control Laboratory, Department of Kinesiology, Durham, NH 03824, USA. rvc@cisunix.unh.edu
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| pubmed:publicationType |
Journal Article,
Comparative Study,
Research Support, Non-U.S. Gov't
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