Electromyographic studies of the lumbar trunk musculature during the development of axial torques

Pope, Malcolm H.; Andersson, Gunnar; Broman, H.; Svensson, Mats Y.; Zetterberg, Carl

doi:10.1002/jor.1100040305

Cited by 107 publications

(43 citation statements)

References 17 publications

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“…This finding was similarly demonstrated in some previous studies [27,28,49] but not in another study by Pope et al [39]. One of the reasons may be due to the EMG data of Pope et al's study [39] not being normalized, so the comparison between muscles may not be the same as other studies where normalization of the EMG data occurred.…”

Section: % --supporting

confidence: 64%

“…Conflicting results on the activity of' abdominal and back muscles have been demonstrated in these previous studies because of different experimental procedures. For example, Pope et al [39] found that there was no difference in activity (non-normalized EMG data) between ipsilateral and contralateral internal oblique. On the other hand, Thelen et al [49] demonstrated higher activity (normalized EMG data) in ipsilateral internal oblique than that of contralateral side.…”

Section: Ct Al I Journul Of Orthopuedic Riwarch 19 (-7001 I 463471mentioning

confidence: 99%

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Functional roles of abdominal and back muscles during isometric axial rotation of the trunk

Parnianpour

Richardson

et al. 2001

Journal Orthopaedic Research

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Electromyographic (EMG) studies have shown that a large number of trunk muscles are recruited during axial rotation. The functional roles of these trunk muscles in axial rotation are multiple and have not been well investigated. In addition, there is no information on the coupling torque at different exertion levels during axial rotation. The aim of the study was to investigate the functional roles of rectus abdominis, external oblique, internal oblique, latissimus dorsi, iliocostalis lumboruni and multifidus during isometric right and left axial rotation at ~OOYU, 70%, 50% and 30' %1 maximum voluntary contractions (MVC) in a standing position.The coupling torques in sagittal and coronal planes were measured during axial rotation to examine the coupling nature of torque at different levels of exertions. Results showed that the coupled sagittal torque switches from nil to flexion at maximum exertion of axial rotation. Generally, higher EMG activities were shown at higher exertion levels for all the trunk muscles. Significant differences in activity between the right and left axial rotation exertions were demonstrated in external oblique, internal oblique, latissimus dorsi and iliocostalis lumborum while no difference was shown in rectus abdominis and multifidus. These results demonstrated the different functional roles of trunk muscles during axial rotation. This is important considering that the abdominal and back muscles not only produce torque but also maintain the spinal posture and stability during axial rotation exertions. The changing coupling torque direction in the sagittal plane when submaximal to maximal exertions were compared may indicate the complex nature of the kinetic coupling of trunk muscles.

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Section: % --supporting

confidence: 64%

Section: Ct Al I Journul Of Orthopuedic Riwarch 19 (-7001 I 463471mentioning

confidence: 99%

Functional roles of abdominal and back muscles during isometric axial rotation of the trunk

Parnianpour

Richardson

et al. 2001

Journal Orthopaedic Research

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“…Granata and England [12] emphasized the stabilizing effect of the activity of the oblique muscles in asymmetrical tasks. Trunk twisting indeed coincides with high levels of trunk muscle cocontraction, due to the side effects that the oblique abdominal muscle have in other planes [26][27][28][29]. In line with this explanation, Graham et al [14] showed that a load carried in the hands, which causes an increase in trunk muscle activity, coincided with higher LDS in the same trunk movement.…”

Section: Discussionmentioning

confidence: 89%

Precision of estimates of local stability of repetitive trunk movements

et al. 2013

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Purpose Local dynamic stability of trunk movements quantified by means of the maximum Lyapunov exponent (k max ) can provide information on trunk motor control and might offer a measure of trunk control in low-back pain patients. It is unknown how many repetitions are necessary to obtain sufficiently precise estimates of k max and whether fatigue effects on k max can be avoided while increasing the number of repetitions. Method Ten healthy subjects performed 100 repetitions of trunk movements in flexion, of trunk rotation and of a task combining these movement directions. k max was calculated from thorax, pelvis and trunk (thorax relative to pelvis) kinematics. Data series were analyzed using a bootstrap procedure; ICC and coefficient of variation were used to quantify precision as a function of the number of cycles analyzed. ANOVA was used to compare movement tasks and to test for effects of time.Results Trunk local stability reached acceptable precision level after 30 repetitions. k max was higher (indicating lower stability) in flexion, compared to rotation and combined tasks. There was no time effect (fatigue). k max of trunk movement was lower and less variable than that of thorax and pelvis movements. Conclusions The data provided allow for an informed choice of the number of repetitions in assessing local dynamic stability of trunk movements, weighting the gain in precision against the increase in measurement effort. Within the 100 repetitions tested, fatigue did not affect results. We suggest that increased stability during asymmetric movement may be explained by higher co-activation of trunk muscles.

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“…Adams and Hutton [3] have shown that in forward flexion the disc is less tolerant to compression and the facet joints may disengage, allowing greater torsion on the intervertebral disc, placing the discs fibers in a position much more vulnerable to injury [65,70].…”

Section: Introductionmentioning

confidence: 99%

“…For this reason many lifting guides, including the NIOSH guide, suggest that all lifting occur between knee and shoulder level, where the trunk muscles are close to their resting length. Significantly greater concurrent muscle activation and loading occur during twisting motions of the trunk as a strategy to enhance trunk stability [65]. However, this coactivation increases loading, because the antagonist muscles in the trunk must compete with the agonist muscles.…”

Section: Introductionmentioning

confidence: 99%

Is there a rational basis for post-surgical lifting restrictions? 2. Possible scientific approach

Pope

Magnusson

Wilder

et al. 1999

European Spine Journal

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IntroductionAfter surgery it is a common practice to prescribe lifting restrictions. In a companion paper [38] we demonstrated that, in practice, there is no consistency in these restrictions. The restrictions appear to be based on a premise that the spine is weaker and thus subject to re-injury when there has been some disruption of the functional spinal motion unit (FSU) due to surgery. However re-injury is seldom reported in the literature and restrictions do affect return to work [37, 42].From a biomechanical standpoint, the spine is an unstable structure without proper functioning of the paraspinal musculature. A lumbar spine, stripped of muscle, will buckle under compressive loads as low as 90 N. Other structures, which could be modified by surgery, are important. The basic shape of the vertebrae, especially the configuration of the facet joints, also add to the stabilization of the FSU. Panjabi's seminal contributions have delineated the specific role of reach FSU structure [53][54][55][56][57][58][59][60][61].Posture is most important in the risk for low back pain (LBP) and herniated nucleus pulposus (HNP). In one study, positive associations were also seen for frequent lifting with arms extended (relative risk, RR = 1.87) and twisting while lifting (RR = 1.90). Increased risk of HNP has been associated with lifting while twisting [32]. Lifting with knees straight and back bent increased the risk of Abstract Lifting restrictions postoperatively are quite common but there appears to be little scientific basis for them. Lifting restricitions are inhibitory in terms of return to work and may be a factor in chronicity. The mean changes in functional spinal motion unit (FSU) stiffness with in vitro or computer-simulated discectomies, facetectomies and laminectomies were reviewed from the literature. We modified the NIOSH lifting equation to include another multiplier related to stiffness change post surgery. The new recommended lifts were computed for different lifting conditions seen in industry. The reduction of rotational stiffness ranged from 21% to 41% for a discectomy, 1% to 59% for a facetectomy and 4% to 16% for a partial laminectomy. The recommended lifts based on our modified equation were adjusted accordingly. There is no rational basis for current lifting resctrictions. The risk to the spine is a function of many other variables as well as weight (i.e., distance of weight from body). The adjusted NIOSH guidelines provide a reasonable way to estimate weight restrictions and accomodations such as lifting aids. Such resitrictions should be as liberal as possible so as to facilitate, not prevent, return to work. Patients need more advice regarding lifting activities and clinicians should be more knowledgeable about the working conditions and constraints of a given workplace to effectively match the solution to the patient's condition.Key words Lifting · Surgery · Return to work · Low back pain · NIOSH ORIGINAL ARTICLE Eur Spine J (1999) 8 : 179-186

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Electromyographic studies of the lumbar trunk musculature during the development of axial torques

Cited by 107 publications

References 17 publications

Functional roles of abdominal and back muscles during isometric axial rotation of the trunk

Functional roles of abdominal and back muscles during isometric axial rotation of the trunk

Precision of estimates of local stability of repetitive trunk movements

Is there a rational basis for post-surgical lifting restrictions? 2. Possible scientific approach

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