The Effect of a Variable Lumbar Erector Spinae Sagittal Plane Moment Arm on Predicted Spinal Loading

2002 ◽  
Vol 46 (13) ◽  
pp. 1061-1065
Author(s):  
Michael J. Jorgensen ◽  
William S. Marras ◽  
Thomas R. Waters
Keyword(s):  
Sagittal Plane ◽  
Biomechanical Model ◽  
Large Degree ◽  
Erector Spinae ◽  
Moment Arm ◽  
Spinal Loading ◽  
Spinal Loads ◽  
Neutral Posture ◽  
Lifting Task ◽  
Male Subjects

Recent research indicates that the sagittal plane moment arm of the erector spinae decreases at the L5/S1 level during torso flexion. The objective of this study was to assess the predicted L5/S1 spinal loading from a lifting task when allowing the erector spinae sagittal plane moment arm to vary during torso flexion. Nineteen male subjects lifted three loads from two origin locations to an upright neutral posture. Spinal loading was predicted from an EMG-assisted biomechanical model that allowed the erector spinae moment arm to vary during torso flexion. The predicted lateral, anterior-posterior shear and compression forces increased by 7.4%, 11.1% and 6.6%, respectively, when compared to using a biomechanical model that kept the erector spinae moment arm constant. These results suggest that models that account for the varying erector spinae moment arm predict greater spinal loads, especially for motions that involve a large degree of torso flexion.

Comparison of Spinal Loads in Kneeling and Standing Postures during Manual Materials Handling

2005 ◽  
Vol 49 (14) ◽  
pp. 1320-1324
Author(s):  
Gang Yang ◽  
Riley Splittstoesser ◽  
Gregory Knapik ◽  
David Trippany ◽  
Sahika Vatan Korkmaz ◽  
...  
Keyword(s):  
Biomechanical Model ◽  
Job Design ◽  
Low Back ◽  
Spinal Loading ◽  
Materials Handling ◽  
Spinal Loads ◽  
Increased Risk ◽  
Manual Materials Handling ◽  
Free Dynamic ◽  
Anterior Posterior

Kneeling in a restricted posture during manual materials handling has been associated with increased risk of low back pain. Little is known about the effect of kneeling posture on spinal loads. The purpose of this study was to compare differences in spinal loading between kneeling and standing postures for lifting tasks. Twelve subjects asymmetrically lifted luggage of three weights to three heights from floor while kneeling. Three subjects also performed the same tasks from waist height while standing. An adapted free-dynamic EMG-assisted biomechanical model was used to calculate spinal loads. Statistical analysis showed that there was no difference in compression between kneeling and standing (p=0.9605), but kneeling resulted in increased anterior-posterior and lateral shear forces on the lumbar spine (p =0.0002 and p<0.0001, respectively). Spinal loading changes while kneeling in a restricted posture may increase the risk of low back injury and must be considered in ergonomic job design.

Comparison of Biomechanical Human Neck Models: Muscle Forces and Spinal Loads at C4/5 Level

1999 ◽  
Vol 15 (2) ◽  
pp. 120-138 ◽  
Author(s):  
Hyeonki Choi ◽  
Ray Vanderby
Keyword(s):  
Cervical Spine ◽  
Three Dimensional ◽  
Biomechanical Model ◽  
Distribution Patterns ◽  
Muscle Forces ◽  
Spinal Loads ◽  
Joint Loads ◽  
Electromyographic Signals ◽  
Male Subjects ◽  
Maximum Exertion

This study developed a three-dimensional biomechanical model to investigate the internal loads on the human neck that result from isometrically generated loads resisted by a force on the head. The first goal was to apply the double-optimization (DOPT) method, the EMG-based method, and the EMG assisted optimization (EMGAO) method to the neck model, calculating muscle forces and C4/5 cervical joint loads for each method. The second goal was to compare the results of the different methods, and the third was to determine maximum exertion forces in the cervical spine for isometric contractions. To formulate the EMG-based model, electromyographic signals were collected from 10 male subjects. EMG signals were obtained from 8 sites around the C4/5 level of the neck by surface electrodes, while the subject performed near maximum, isometric exertions. The mean maximum values (±SD) calculated for C4/5 joint compressive forces during peak exertions were 1654 (±308) N in flexion by the EMG method, 1674 (±319) N in flexion by the EMGAO method, and 1208 (±123) N in extension by the DOPT method. In contrast to the DOPT method, the EMG and EMGAO methods showed activation of all the muscles, including the antagonists, and accommodated various load distribution patterns among the agonist muscles during generation of the same magnitude of moments, especially in lateral bending. The EMG and EMGAO methods predicted higher cervical spinal loads than previously published results by the DOPT method. These results may be helpful to engineers and surgeons who are designing and using cervical spine implants and instrumentation.

Stability as a constraint in sagittal plane human force exertion modeling

1998 ◽  
Vol 1 (1) ◽  
pp. 23-39
Author(s):  
Carter J. Kerk ◽  
Don B. Chaffin ◽  
W. Monroe Keyserling
Keyword(s):  
Muscle Strength ◽  
Ankle Joint ◽  
Coefficient Of Friction ◽  
Sagittal Plane ◽  
Biomechanical Model ◽  
Whole Body ◽  
The Stability ◽  
Joint Center ◽  
Static Conditions ◽  
Stability Limits

The stability constraints of a two-dimensional static human force exertion capability model (2DHFEC) were evaluated with subjects of varying anthropometry and strength capabilities performing manual exertions. The biomechanical model comprehensively estimated human force exertion capability under sagittally symmetric static conditions using constraints from three classes: stability, joint muscle strength, and coefficient of friction. Experimental results showed the concept of stability must be considered with joint muscle strength capability and coefficient of friction in predicting hand force exertion capability. Information was gained concerning foot modeling parameters as they affect whole-body stability. Findings indicated that stability limits should be placed approximately 37 % the ankle joint center to the posterior-most point of the foot and 130 % the distance from the ankle joint center to the maximal medial protuberance (the ball of the foot). 2DHFEC provided improvements over existing models, especially where horizontal push/pull forces create balance concerns.

Analysis of Muscle Activity Using Surface Electromyography for Muscle Performance in Manual Lifting Task

2014 ◽  
Vol 564 ◽  
pp. 644-649 ◽  
Author(s):  
Halim Isa ◽  
Rawaida ◽  
Seri Rahayu Kamat ◽  
A. Rohana ◽  
Adi Saptari ◽  
...  
Keyword(s):  
Muscle Activity ◽  
Surface Electromyography ◽  
Biceps Brachii ◽  
Twist Angle ◽  
Erector Spinae ◽  
Manual Lifting ◽  
Experienced Fatigue ◽  
Left And Right ◽  
Lifting Task ◽  
Load Mass

In industries, manual lifting is commonly practiced even though mechanized material handling equipment are provided. Manual lifting is used to transport or move products and goods to a desired place.Improper lifting techniquescontribute to muscle fatigue and low back pain that can lead to work efficiency and low productivity.The objective of this study were to analyze muscle activity in the left and right Erector Spinae, and left and right Biceps Brachii of five female subjects while performing manual lifting taskwithdifferent load mass, lifting height and twist angle.The muscle activitywere measured and analyzed using surface electromyography (sEMG).This study found that the right Biceps Brachii, right and left Erector Spinae experienced fatigue while performingasymmetric lifting (twist angle = 90°) at lifting height of 75 cm and 140 cm with load mass of 5 kg and 10 kg. Meanwhile, the left Biceps Brachii experienced fatigue when the lifting task was set at lifting height of 75 cm, load mass of 5 kg and twist angle of 90°.The load mass and lifting height has a significant influence to Mean Power Frequency (MPF) for left Biceps Brachii, left and right Erector Spinae. This study concluded that reducing the load mass can increase the muscles performance which can extend the transition-to-fatigue stage in the left and right Biceps Brachii and Erector Spinae.

The Effect of Lifting vs. Lowering on Spinal Loading

1996 ◽  
Vol 40 (13) ◽  
pp. 599-603 ◽  
Author(s):  
Kermit G. Davis
Keyword(s):  
Muscle Activity ◽  
Dimensional Space ◽  
Three Dimensional ◽  
Muscle Forces ◽  
Shear Forces ◽  
Spinal Loading ◽  
Spinal Loads ◽  
Trunk Strength ◽  
Anterior Posterior ◽  
Three Dimensional Space

In industry, workers perform tasks requiring both lifting and lowering. During concentric lifting, the muscles are shortening as the force is being generated. Conversely, the muscle lengthens while generating force during eccentric lowering. While research on various lifting tasks is extensive, there has been limited research performed to evaluate the lowering tasks. Most of the research that does exist on lowering has investigated muscle activity and trunk strength. None of these studies have investigated spinal loading. The current study estimated the effects of lifting and lowering on spinal loads and predicted moments imposed on the spine. Ten subjects performed both eccentric and concentric lifts under sagittally symmetric conditions. The tasks were performed under isokinetic trunk velocities of 5, 10, 20, 40, and 80 deg/s while holding a box with weights of 9.1, 18.2, and 27.3 kg. Spinal loads and predicted moments in three dimensional space were estimated by an EMG-assisted model which has been adjusted to incorporate the artifacts of eccentric lifting. Eccentric strength was found to be 56 percent greater than during concentric lifting. The lowering tasks produced significantly higher compression forces but lower anterior-posterior shear forces than the concentric lifting tasks. The differences in the spinal loads between the two lifting tasks were attributed to the internal muscle forces and unequal moments resulting from differences in the lifting path of the box. Thus, the differences between the lifting tasks resulted from different lifting styles associated with eccentric and concentric movements

An Investigation of the Variability in Human Performance during Manual Material Handling Activities

1994 ◽  
Vol 38 (10) ◽  
pp. 578-582
Author(s):  
Gary A. Mirka ◽  
Ann Baker
Keyword(s):  
Material Handling ◽  
Human Performance ◽  
Sagittal Plane ◽  
Coupling Effect ◽  
Peak Velocity ◽  
Three Dimensional ◽  
Biomechanical Model ◽  
Manual Material Handling ◽  
Symmetric Lifting ◽  
Dependent Position

The goal of this study was to quantify the variability of the three-dimensional kinematic and kinetic parameters describing the motion of the torso during the performance of sagittally symmetric lifting tasks. Subjects performed eight repetitions of simple lifting tasks described by three levels of coupling (poor, fair and good) and seven levels of load (4.5, 9, 13.5, 18, 22.5, 27 and 31.5 kg). The three-dimensional, time dependent position, velocity and acceleration of the lumbar spine were monitored using the Lumbar Motion Monitor. These measures were then input into a dynamic biomechanical model which calculated torque about the L5/S1 joint in the sagittal plane. The results of the kinematic analysis showed significant variability in the magnitude of the peak velocity and acceleration in the sagittal plane and also showed significant motion in the transverse and coronal planes. The kinetic analysis showed an increase in the variability of the peak dynamic torque with greater levels of load but no coupling effect.

INVESTIGATION OF THE INFLUENCE OF THE ELBOW JOINT REACTION ON THE PREDICTED MUSCLE FORCES USING DIFFERENT OPTIMIZATION FUNCTIONS

2009 ◽  
Vol 12 (01) ◽  
pp. 31-43 ◽  
Author(s):  
Rositsa T. Raikova
Keyword(s):  
Objective Function ◽  
Elbow Joint ◽  
Degrees Of Freedom ◽  
Sagittal Plane ◽  
Biomechanical Model ◽  
Moment Equation ◽  
Muscle Forces ◽  
Joint Stability ◽  
Biarticular Muscles ◽  
Joint Reaction

Less attention is paid to joint reactions when optimization tasks are solved aiming to predict individual muscle forces driving a biomechanical model. The reactions are important, however, for joint stability and for prevention from injuries, especially for fast motions and submaximal loading. The purpose of the paper is to investigate the influence of the joint reaction as a criterion in an objective function and to study the possibilities for prediction of antagonistic co-contraction. Planar elbow flexions in the sagittal plane with duration from 0.4 to 2 s are simulated, and muscle forces and elbow joint reaction are calculated solving numerically optimization tasks formulated for models with one (elbow moment equation only) and two (elbow and shoulder moment equations) degrees of freedom (DOF). The objective function is a weighted sum of muscle forces and joint reaction raised to different powers. The following conclusions can be made: (1) if the joint reaction is included in the objective function, antagonistic co-contraction can be predicted even for 1 DOF model; in some situations the use of such objective function can destroy the synergistic muscles' action; (2) the prediction of antagonistic muscles' co-contraction for 2 DOF model depends on the way the biarticular muscles are modeled, and this is valid for both dynamic and quasistatic conditions; if there are no biarticular muscles, antagonistic co-contraction cannot be predicted in one joint using popular objective functions, like minimum of sum of muscle forces or muscle stresses raised to a power.

Cervical Spine Musculotendon Lengths When Reading a Tablet in Three Seated Positions

2020 ◽  
pp. 1-8
Author(s):  
Kaitlin M. Gallagher ◽  
Anita N. Vasavada ◽  
Leah Fischer ◽  
Ethan C. Douglas
Keyword(s):  
Cervical Spine ◽  
Biomechanical Model ◽  
Segment Length ◽  
Moment Arm ◽  
Wireless Technology ◽  
Sitting Posture ◽  
Full Flexion ◽  
Length Changes ◽  
Splenius Capitis ◽  
Gravitational Moment

A popular posture for using wireless technology is reclined sitting, with the trunk rotated posteriorly to the hips. This position decreases the head’s gravitational moment; however, the head angle relative to the trunk is similar to that of upright sitting when using a tablet in the lap. This study compared cervical extensor musculotendon length changes from neutral among 3 common sitting postures and maximum neck flexion while using a tablet. Twenty-one participants had radiographs taken in neutral, full-flexion, and upright, semireclined, and reclined postures with a tablet in their lap. A biomechanical model was used to calculate subject-specific normalized musculotendon lengths for 27 cervical musculotendon segments. The lower cervical spine was more flexed during reclined sitting, but the skull was more flexed during upright sitting. Normalized musculotendon length increased in the reclined compared with an upright sitting position for the C4-C6/7 (deep) and C2-C6/7 (superficial) multifidi, semispinalis cervicis (C2-C7), and splenius capitis (Skull-C7). The suboccipital (R2 = .19–.71) and semispinalis capitis segment length changes were significantly correlated with the Skull-C1 angle (0.24–0.51). A semireclined reading position may be an ideal sitting posture to reduce the head’s gravitational moment arm without overstretching the assessed muscles.

scholarly journals Changes in the Plantarflexion Moment Arm of the Achilles Tendon Following Total Ankle Arthroplasty

2020 ◽  
Vol 5 (4) ◽  
pp. 2473011420S0048
Author(s):  
Francesca E. Wade ◽  
Gregory Lewis ◽  
Andrea H. Horne ◽  
Lauren Hickox ◽  
Michael C. Aynardi ◽  
...  
Keyword(s):  
Achilles Tendon ◽  
Ankle Joint ◽  
Sagittal Plane ◽  
Total Ankle Arthroplasty ◽  
Moment Arm ◽  
Talar Dome ◽  
Ankle Arthroplasty ◽  
Joint Structure ◽  
Joint Axis ◽  
Mean Differences

Category: Ankle; Ankle Arthritis Introduction/Purpose: Deficits in ankle joint kinetics following total ankle arthroplasty (TAA) may be attributed to a reduction in the force-generating capacity of ankle joint muscles, but it is also important to consider the alterations to joint structure that may accompany this procedure. One key parameter indicative of joint structure with the potential to be influenced by TAA is the plantarflexion moment arm of the Achilles tendon (ATma). ATma is an indicator of the potential for the tendon force to produce plantarflexion moment that is determined by the three-dimensional line of action of the tendon relative to the ankle joint axis. The purpose of this study was to assess pre-to-post TAA changes in ATma; we hypothesized that pre- and post-TAA moment arms would not be different. Methods: We tested 10 TAA patients (age at surgery: 62.86 +- 9.72 y; height: 1.72 +- 0.08 m; body mass: 97.81 +- 20.89 kg) at pre-operative (˜ 1 mo pre) and post-operative (˜6 mo post) visits. All procedures involving testing of human subjects were approved by the Penn State Hershey Medical Center Institutional Review Board. ATma were measured using a method that combined ultrasound imaging of the tendon with 3D motion tracking of both the ultrasound probe and the ankle joint. The tendon and joint axis were located during trials in which the patients were seated with the knee extended while the ankle joint was voluntarily rotated in the sagittal plane. We also examined sagittal-plane weightbearing radiographs (pre- and post-op) to determine the AP distance from the center of the talar dome to the posterior margin of the calcaneus. Pre- and post-op ATma were compared using a paired t-test and regression. Results: No significant mean differences were found between post-op ATma and pre-op ATma (p = 0.360). Despite this, some patients were found to have large differences between pre- and postoperative ATma. For example, participants 1, 3, and 8 exhibited changes of -54.22%, +64.14% and +123.98% (pre-to-post) respectively (Figure 1). A moderate correlation between pre- and post-op ATma was found (r2 = 0.461, p = 0.031), indicating that only 46.1% of the variance in post-op ATma was explained by pre-op ATma (Figure 1). The normalized AP distance measured from the radiographs did not significantly change on average pre- to post-TAA (p = 0.561), and we found the change in this distance to correlate with the change in ATma (r2 = 0.370, p = 0.062). Conclusion: This is the first investigation of whether TAA alters ATma. Our results supported our hypothesis that pre-operative ATma predicts post-operative ATma. However, our hypothesis is supported only when the mean differences are considered, as there were sizeable differences for individuals. Despite a non-significant average change in ATma following TAA, at the individual level substantial changes in ATma were observed in seven of the 10 patients. Change in ATma was only partly explained by change in the AP position of the talar dome. Change in ATma has potential consequences for function in terms of ankle plantarflexor strength and walking velocity.

Stadiometer Measurements of Driver'S Spinal Response to Steering Force and Vibration

2000 ◽  
Vol 44 (30) ◽  
pp. 5-485-5-488
Author(s):  
Christine M. Haslegrave ◽  
Myles A. Mellor
Keyword(s):  
Driving Simulator ◽  
Task Force ◽  
Experimental Conditions ◽  
Period Analysis ◽  
Spinal Loading ◽  
Minute Period ◽  
Driving Task ◽  
Steering Torque ◽  
Seat Vibration ◽  
Male Subjects

The effects on spinal loading of two aspects of the driving task - force exertion while steering and exposure to 4 Hz 1ms−2 peak vertical seat vibration - were investigated with a group of six male subjects seated in a driving simulator. In addition, the effect of the combination of the two aspects was tested. Spinal shrinkage was measured with a precision seated stadiometer over a 40 minute period. Analysis of variance showed that both steering actions and vibration had a significant effect on spinal loading (p<0.05 and p<0.025 respectively), even though the steering torque (5Nm) was moderate. The response was significantly greater in all three experimental conditions than in static sitting (in the same posture). There appeared to be a tendency for the mean spinal shrinkage to increase from 6.0 mm when steering to 7.1mm under vibration and 8.7mm when steering and vibration were combined, but the only difference which was statistical significant was that between the combined condition and steering alone (t test, p<0.01).

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