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Quadriceps activity and movement reactions in response to unpredictable sagittal support-surface translations in women with patellofemoral pain.
Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering, Sjukgymnastik.
Umeå universitet, Medicinska fakulteten, Institutionen för strålningsvetenskaper, Radiofysik.
Umeå universitet, Medicinska fakulteten, Institutionen för samhällsmedicin och rehabilitering, Sjukgymnastik.ORCID-id: 0000-0002-0366-4609
2008 (Engelska)Ingår i: Journal of Electromyography & Kinesiology, ISSN 1050-6411, E-ISSN 1873-5711, Vol. 18, nr 2, s. 298-307Artikel i tidskrift (Refereegranskat) Published
Abstract [en]

Patellofemoral pain (PFP) may be related to unfavorable knee joint loading. Delayed and/or reduced activity of vastus medialis obliquus (VMO) and different movement patterns have been identified in individuals with PFP in some studies, whereas other studies have failed to show a difference compared to non-affected controls. The discrepancy between study results may depend on the different tasks that have been investigated. No previous study has investigated these variables in postural responses to unpredictable perturbations in PFP. Whole body three dimensional kinematics and surface EMG of quadriceps muscles activation was studied in postural responses to unpredictable support surface translations in 17 women with PFP who were pain free at the time of testing, and 17 matched healthy controls. The results of the present study showed earlier onset of VMO activity and associated changes in kinematics to anterior platform translation in the PFP subjects. We suggest that the relative timing between the portions quadriceps muscles may be task specific and part of an adapted response in attempt to reduce knee joint loading. This learned response appears to remain even when the pain is no longer present.

Ort, förlag, år, upplaga, sidor
2008. Vol. 18, nr 2, s. 298-307
Nyckelord [en]
knee, muscle coordination, kinematics
Forskningsämne
sjukgymnastik
Identifikatorer
URN: urn:nbn:se:umu:diva-9374DOI: 10.1016/j.jelekin.2006.10.004PubMedID: 17158068OAI: oai:DiVA.org:umu-9374DiVA, id: diva2:149045
Tillgänglig från: 2008-03-27 Skapad: 2008-03-27 Senast uppdaterad: 2018-06-09Bibliografiskt granskad
Ingår i avhandling
1. Motor control of the knee: kinematic and EMG studies of healthy individuals and people with patellofemoral pain
Öppna denna publikation i ny flik eller fönster >>Motor control of the knee: kinematic and EMG studies of healthy individuals and people with patellofemoral pain
2005 (Engelska)Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
Abstract [en]

Patellofemoral pain (PFP) is believed to be associated with deficits in coordination between the different heads of the quadriceps muscle; however, considerable debate exists in the literature regarding the presence of such a deficit. Discrepancies between studies may be explained by differences in experimental tasks, such as whether the task is performed with open (OKC) or closed kinetic chain (CKC), or whether the activity is voluntary or triggered. Particular interest has been directed toward the function of the vastus medialis obliquus (VMO), which is a short muscle with limited ability to exert torque across the knee joint, but probably has a particular role in controlling patellofemoral joint position. Another short muscle that may influence knee joint position control is popliteus (POP), which is located in the back of the knee.

This thesis investigates task specific activity of quadriceps in CKC versus OKC and studies the relative activity between the four heads of the quadriceps in PFP subjects compared to controls without knee pain in voluntary activity (CKC and OKC) and postural responses to balance perturbations. In addition, this thesis investigates the presumed function of POP for control of joint position in postural tasks in healthy individuals.

All subjects were of normal weight and height and between 18 and 40 years. Quadriceps activity was tested for isometric with identical joint configuration in CKC and OKC, and it was performed as a reaction time task. Balance perturbations were elicited by unpredictable anterior and posterior translations of the support surface. Function of POP was investigated in unpredictable support surface translations and in self induced provocations to balance by moving the arms. Muscle activity was recorded with electromyography (EMG). Optic kinematic analysis was used to obtain specific movement responses to perturbations of balance.

The quadriceps muscles were activated differently in CKC and OKC. VMO was activated earlier and to a greater degree in CKC. Rectus femoris was activated earlier and to a greater degree in OKC. PFP subjects reacted slower in both CKC and OKC, but there was no difference between groups in the relative activity between the different heads of the quadriceps. In the unpredictable support surface translation in the anterior direction, PFP subjects responded with earlier onset of VMO and with greater trunk and hip flexion in the anterior translation. POP activation in response to support surface translations in both directions occurred before all other muscles measured. In the self-initiated provocations of balance, POP was activated after the initiation of the balance provocation.

This thesis concludes that quadriceps activity was task specific. The lack of difference between groups in OKC and CKC, and the difference between groups in postural responses suggest that variations in motor behaviour may occur only in tasks habitually performed. Differences in muscle activation patterns may be related to compensatory strategies to unload the quadriceps muscles and the patellofemoral joint. Furthermore, this thesis suggests that POP muscle may have a particular role in active control of the knee joint.

Ort, förlag, år, upplaga, sidor
Umeå: Samhällsmedicin och rehabilitering, 2005. s. 90
Serie
Umeå University medical dissertations, ISSN 0346-6612 ; 987
Nyckelord
Kinematics; Kinetic chain tasks; Knee; Motor Control; Muscle activity; Patellofemoral pain; Unpredictable perturbations
Nationell ämneskategori
Sjukgymnastik
Identifikatorer
urn:nbn:se:umu:diva-644 (URN)91-7305-951-X (ISBN)
Disputation
2005-12-16, Aulan, Vårdvetarhuset, Umeå Universitet, Umeå, 09:00 (Engelska)
Opponent
Handledare
Tillgänglig från: 2005-11-22 Skapad: 2005-11-22 Senast uppdaterad: 2015-01-21Bibliografiskt granskad

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