A systems-level perspective of the biomechanics of the trunk flexion-extension movement: Part II – Fatigued low back conditions

Jin, Sangeun; Mirka, Gary A.

doi:10.1016/j.ergon.2015.01.007

Cited by 8 publications

(3 citation statements)

References 34 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This biomechanical response, which occurred by maintaining contact between upper thighs and a table, denotes a more differentiated activation in the trunk musculature at asymmetric static posture maintenance. In other words, the lower extremity can play a significant role in trunk biomechanics, in the agreement of the results of previous studies (Jin & Mirka, 2015a; 2015b). The results of this study have the potential to be extended to other occupations that require asymmetric trunk postures and restrictions on lower extremity motions through leaning against a static surface.…”

Section: Discussionsupporting

confidence: 93%

“…It is not a new idea that the lower extremity restrictions can play a significant role in trunk biomechanics. Jin and Mirka (2015a, 2015b) collected empirical data during trunk flexion-extension with and without a pelvic/lower extremity constraint, and revealed biomechanical interactions between trunk and lower extremities, suggesting “a super global system” that extends the local and global systems for the lumbar spine proposed by Bergmark (1989). Based on this evidence, exploring the role of the lower extremities on trunk biomechanics in asymmetric trunk postures is also of value.…”

Section: Introductionmentioning

confidence: 87%

See 1 more Smart Citation

Effects of a Passive Back-Support Exosuit on Erector Spinae and Abdominal Muscle Activity During Short-Duration, Asymmetric Trunk Posture Maintenance Tasks

Kang,

Mirka

2023

Hum Factors

Self Cite

View full text Add to dashboard Cite

Objective To examine the effects of asymmetry and lower extremity mobility restrictions on the effectiveness of a passive back-support exosuit in short-duration, static trunk flexion postures. Background The effectiveness of trunk exoskeletons/suits for sagittally symmetric trunk posture maintenance has been investigated, but there has been limited study of the effects of asymmetric trunk postures or lower extremity motion restriction. Method Sixteen participants held trunk flexion postures involving trunk flexion (20°, 40°, 60°), asymmetry (0°, 30°), and lower extremity mobility (Free, Restricted) for 3 s. Participants held these postures with and without an exosuit while erector spinae and abdominal muscle activities were collected. Results There were no significant interactions between exosuit and asymmetry or exosuit and lower extremity motion restrictions, indicating no significant effects of these factors on the effectiveness of the exosuit at reducing trunk muscle activity. The exosuit was found to be effective at reducing erector spinae muscle activity regardless of asymmetry of posture or lower extremity restrictions (average 21%, from 11.2% MVC to 8.8% MVC). The magnitude of the erector spinae activity at 60° of trunk flexion with the exosuit was similar to that seen at 20° without the exosuit. Conclusion The exosuit consistently provided biomechanical benefit through reduced activation of the erector spinae muscles and neither asymmetry of trunk posture nor lower extremity restriction influenced this effectiveness. Application Trunk exoskeletons/suits can reduce trunk muscle activation and understanding how characteristics of the trunk postures assumed impact these responses may help target tasks wherein these devices may be effective.

show abstract

Section: Discussionsupporting

confidence: 93%

Section: Introductionmentioning

confidence: 87%

Effects of a Passive Back-Support Exosuit on Erector Spinae and Abdominal Muscle Activity During Short-Duration, Asymmetric Trunk Posture Maintenance Tasks

Kang,

Mirka

2023

Hum Factors

Self Cite

View full text Add to dashboard Cite

show abstract

“…The conceptual model classified the active system into a local system (i.e., all muscles have their origin and insertion at the vertebrae) controlling the spinal curvature and a global system (i.e., trunk muscles connect the thoracic cage and pelvis) generating the required moment to hold the trunk. Based on Bergmark’s work, two recent studies took the conventional model one step further by focusing on the system-level perspective (Jin & Mirka, 2015a, 2015b). The previous studies gathered data to reveal an interaction between the lower body and trunk during trunk flexion-extension and revealed the role of “a superglobal system,” including the active and passive tissues that directly or indirectly influence the trunk biomechanics through their actions on the pelvic girdle.…”

Section: Discussionmentioning

confidence: 99%

Significance of Lower Body Postures in Chair Design

et al. 2021

Self Cite

View full text Add to dashboard Cite

Objective This study examined a system-level perspective to investigate the changes in the whole trunk and head postures while sitting with various lower extremity postures. Background Sitting biomechanics has focused mainly on the lumbar region only, whereas the anatomy literature has suggested various links from the head and lower extremity. Method Seventeen male participants were seated in six lower extremity postures, and the trunk kinematics and muscle activity measures were captured for 5 s. Results Changes in the trunk-thigh angle and the knee angle affected the trunk and head postures and muscle recruitment patterns significantly, indicating significant interactions between the lower extremity and trunk while sitting. Specifically, the larger trunk-thigh angle (T135°) showed more neutral lumbar lordosis (4.0° on average), smaller pelvic flexion (1.8°), smaller head flexion (3.3°), and a less rounded shoulder (1.7°) than the smaller one (T90°). The smaller knee angle (K45°) revealed a more neutral lumbar lordosis (6.9°), smaller pelvic flexion (9.2°), smaller head flexion (2.6°), and less rounded shoulder (2.4°) than the larger condition (K180°). The more neutral posture suggested by the kinematic measures confirmed significantly less muscular recruitment in the trunk extensors, except for a significant antagonistic co-contraction. Conclusion The lower and upper back postures were more neutral, and back muscle recruitment was lower with a larger trunk-thigh angle and a smaller knee angle, but at the cost of antagonistic co-contraction. Application The costs and benefits of each lower extremity posture can be used to design an ergonomic chair and develop an improved sitting strategy.

show abstract

A systems-level perspective of the biomechanics of the trunk flexion-extension movement: Part I – Normal low back condition

Jin

Mirka

2015

International Journal of Industrial Ergonomics

Self Cite

View full text Add to dashboard Cite

Most of the previous studies of the lumbar region have not considered the influence of pelvic and lower extremity characteristics on the performance of the lumbar region. The goal of the current study was to explore these more systems-level effects by assessing the effects of a pelvic/lower extremity constraint on the biomechanical response of the lumbar spine in an in-vivo experiment. Twelve participants performed full range of motion, sagittal-plane trunk flexion-extension movements under two conditions: unconstrained stoop movement and pelvic/lower extremity constrained stoop movement (six repetitions in each condition over three days). Kinematics and muscle activities of the trunk and lower extremity muscles were monitored. Results showed a significant effect of pelvic/lower-extremity constraint on a number of lumbar performance measures.Trunk flexion angle was, as expected, significantly reduced with the lower extremity constraints (81 degrees (free stoop) vs. 56 degrees (lower extremity constrained)). At a more local level, there was a 6.4% greater peak lumbar flexion angle and a 9.1% increase in the lumbar angle at which the trunk extensor musculature demonstrated flexionrelaxation in the constrained stooping condition as compared to the unconstrained stooping condition. Also, the EMG of the L3/L4 paraspinals was greater in the restricted stooping as compared to the free stooping (16.3% MVC vs. 15.1% MVC).Relevance to Industry: Low back injuries are a significant challenge to many industries and developing accurate models of spinal stress at full stooping postures can help in the development of appropriate interventions to reduce prevalence. Highlights We examined the role of pelvis and lower extremity during trunk flexion-extension. Greater lumbar flexion was observed in the lower extremity constrained condition. Later flexion-relaxation was observed in the lower extremity constrained condition. Greater EMG in low back was observed in the lower extremity constraints condition. A complementary interaction between trunk and lower extremity exists.

show abstract

A systems-level perspective of the biomechanics of the trunk flexion-extension movement: Part II – Fatigued low back conditions

Cited by 8 publications

References 34 publications

Effects of a Passive Back-Support Exosuit on Erector Spinae and Abdominal Muscle Activity During Short-Duration, Asymmetric Trunk Posture Maintenance Tasks

Effects of a Passive Back-Support Exosuit on Erector Spinae and Abdominal Muscle Activity During Short-Duration, Asymmetric Trunk Posture Maintenance Tasks

Significance of Lower Body Postures in Chair Design

A systems-level perspective of the biomechanics of the trunk flexion-extension movement: Part I – Normal low back condition

Contact Info

Product

Resources

About