Stabilizing Function of Trunk Flexor-Extensor Muscles Around a Neutral Spine Posture

Cholewicki, Jacek; Panjabi, Manohar M.; Khachatryan, Armen

doi:10.1097/00007632-199710010-00003

Cited by 534 publications

(328 citation statements)

References 21 publications

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“…but the experimental literature on spinal stability (Cholewicki et al, 1997;Van Dieën et al, 2003) revealed that instability may trigger co-contraction, and we conclude that this is also true for the osteoarthritic knee (cf. Buchanan et al, 1996).…”

Section: Local Dynamic Stabilitysupporting

confidence: 60%

“…In the lumbar spine literature, co-contraction could be "explained entirely on the basis of the need for the neuromuscular system to provide […] mechanical stability […]" (Cholewicki et al, 1997(Cholewicki et al, , p.2207. Co-contraction can be an effective strategy to provide stability (Gardner-Morse and Stokes, 2001), but in knee pathology, this was not always found.…”

Section: Introductionmentioning

confidence: 99%

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Determinants of co-contraction during walking before and after arthroplasty for knee osteoarthritis

Fallah-Yakhdani¹,

Bafghi²,

Meijer³

et al. 2012

Clinical Biomechanics

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Background: Knee osteoarthritis patients co-contract in knee-related muscle pairs during walking. The determinants of this co-contraction remain insufficiently clear. Methods: A heterogeneous group of 14 patients was measured before and one year after knee arthroplasty, and compared to 12 healthy peers and 15 young subjects, measured once. Participants walked on a treadmill at several imposed speeds. Bilateral activity of six muscles was registered electromyographically, and cocontraction time was calculated as percentage of stride cycle time. Local dynamic stability and variability of sagittal plane knee movements were determined. The surgeon's assessment of alignment was used. Preoperatively, multivariate regressions on co-contraction time were used to identify determinants of cocontraction. Post-operatively it was assessed if predictor variables had changed in the same direction as co-contraction time. Findings: Patients co-contracted longer than controls, but post-operatively, differences with the healthy peers were no longer significant. Varus alignment predicted co-contraction time. No patient had post-operative varus alignment. The patients' unaffected legs were more unstable, and instability predicted co-contraction time in both legs. Post-operatively, stability normalised. Longer unaffected side co-contraction time was associated with reduced affected side kinematic variability. Post-operatively, kinematic variability had further decreased. Interpretations: Varus alignment and instability are determinants of co-contraction. The benefits of cocontraction in varus alignment require further study. Co-contraction probably increases local dynamic stability, which does not necessarily decrease the risk of falling. Unaffected side co-contraction contributed to decreasing affected side variability, but other mechanisms than co-contraction may also have played a role in decreasing variability.

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Section: Local Dynamic Stabilitysupporting

confidence: 60%

Section: Introductionmentioning

confidence: 99%

Determinants of co-contraction during walking before and after arthroplasty for knee osteoarthritis

Fallah-Yakhdani¹,

Bafghi²,

Meijer³

et al. 2012

Clinical Biomechanics

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“…In this supposed mechanism, spinal buckling causes large localized local tissue deformations and associated painful tissue damage. The degree of stability of the trunk with a given external loading, and a known muscle activation pattern can be quantified with the help of models that analyze the potential energy of the trunk [5,7]. Experimentally, buckling instability cannot be induced by a perturbation, but the amount of trunk excursions (stiffness) [4,8,9] and/or the magnitude and timing of muscular response to a perturbation [18,32] can be recorded.…”

Section: Introductionmentioning

confidence: 99%

Trunk muscular activation patterns and responses to transient force perturbation in persons with self-reported low back pain

2005

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Trunk stability requires muscle stiffness associated with appropriate timing and magnitude of activation of muscles. Abnormality of muscle function has been implicated as possible cause or consequence of back pain. This experimental study compared trunk muscle activation and responses to transient force perturbations in persons with and without self-reported history of low back pain. The objective was to determine whether or not history of back pain was associated with (1) altered anticipatory preactivation of trunk muscles or altered likelihood of muscular response to a transient force perturbation and (2) altered muscle activation patterns during a ramped effort. Twenty-one subjects who reported having back pain (LBP group) and twenty-three reporting no recent back pain (NLBP group) were tested while each subject stood in an apparatus with the pelvis immobilized. They performed 'ramped-effort' tests (to a voluntary maximum effort), and force perturbation tests. Resistance was provided by a horizontal cable from the thorax to one of five anchorage points on a wall track to the subject's right at angles of 0°, 45°, 90°, 135°and 180°to the forward direction. In the perturbation tests, subjects first pulled against the cable to generate an effort nominally 15% or 30% of their maximum extension effort. The effort and the EMG activity of five right/left pairs of trunk muscles were recorded, and muscle responses were detected. In the ramped-effort tests the gradient of the EMG-effort relationship provided a measure of each muscle's activation. On average, the LBP group subjects activated their dorsal muscles more than the NLBP group subjects in a maximum effort task when the EMG values were normalized for the maximum EMG, but this finding may have resulted from lesser maximum effort generated by LBP subjects. Greater muscle preactivation was recorded in the LBP group than the NLBP group just prior to the perturbation. The likelihood of muscle responses to perturbations was not significantly different between the two groups. The findings were consistent with the hypothesis that LBP subjects employed muscle activation in a quasistatic task and preactivation prior to a perturbation in an attempt to stiffen and stabilize the trunk. However, interpretation of the findings was complicated by the fact that LBP subjects generated lesser efforts, and it was not known whether this resulted from anatomical differences (e.g., muscle atrophy) or reduced motivation (e.g., pain avoidance).

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“…Modeling of injury has shown that a reduction of intervertebral stiffness could be compensated by a small increase of 1-2 % maximum voluntary activation (% MVA) in trunk muscle co-activation (Cholewicki et al, 1997). Interestingly, several studies have shown that LBP patients tend to have higher levels of co-activation of trunk muscles than healthy controls (Marras et al, 2001;Lariviere et al, 2002;Van Dieen et al, 2003).…”

Section: Plant Related Impairmentmentioning

confidence: 99%

“…But there appears to be a threshold at 5% MVA, below which muscle contraction can be sustained indefinitely (Bjorksten and Jonsson, 1977). Both modeling and experimental results have shown that healthy controls operate below this critical 5 % MVA threshold for most postural activities like standing, walking, sitting that must be maintained throughout the day (Cholewicki et al, 1997). So it is plausible that even a slight increase in muscle activation following injury could elevate muscle contraction above the critical threshold, resulting in fatigue-related pain.…”

Section: Plant Related Impairmentmentioning

confidence: 99%

Spine stability: The six blind men and the elephant

Reeves

Narendra

Cholewicki

2007

Clinical Biomechanics

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212

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Stability is one of the most fundamental concepts to characterize and evaluate any system. This term is often ambiguously used in spinal biomechanics. Confusion arises when the static analyses of stability are used to study dynamic systems such as the spine. Therefore, the purpose of this paper is to establish a common ground of understanding, using standard, well-defined terms to frame future discussions regarding spine dynamics, stability, and injury. A qualitative definition of stability, applicable to dynamic systems, is presented. Additional terms, such as robustness (which is often confused with stability) and performance are also defined. The importance of feedback control in maintaining stability is discussed. Finally, these concepts are applied to understand low back pain and risk of injury.

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Stabilizing Function of Trunk Flexor-Extensor Muscles Around a Neutral Spine Posture

Cited by 534 publications

References 21 publications

Determinants of co-contraction during walking before and after arthroplasty for knee osteoarthritis

Determinants of co-contraction during walking before and after arthroplasty for knee osteoarthritis

Trunk muscular activation patterns and responses to transient force perturbation in persons with self-reported low back pain

Spine stability: The six blind men and the elephant

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