Back Compression Force Research Articles

Lower Back & Comfortability Analysis of Driving Posture to Mitigate Musculoskeletal Disorders: An Ergonomics Study using Digital Human Modelling in JACK Software

In this paper, the crucial aspect of driver comfort was explored by investigating the prevailing driving postures among individuals, aiming to discern their ergonomic implications and ascertain whether the commonly adopted postures are conducive to musculoskeletal health or pose potential risks. From the last decade vehicle like cars have become one of the common modes of personal transport. Car has high relevance in day-to-day activities like commuting, economic activities and sports etc. The continuous driving of vehicle can lead the driver prone to musculoskeletal disorders such as back pain, spine injury and posture issues. This study is conducted to address the ergonomic aspects of posture of the driver to highlight the risk of Musculoskeletal disorders (MSDs) and to optimize the driving posture. Lower Back Analysis (LBA) and Comfortability Analysis is performed in JACK Software to analyze the driving posture. A DHM (Digital Human Model) is created in JACK Simulation Software according to the collected anthropometric data of an average Pakistani man. A virtual Environment is created in JACK Simulation Software. The posture of the subject is analyzed by taking measurements of the subject’s angle of joints when they are sitting in a driving posture. For Ergonomic Analysis the Driving Posture is evaluated on JACK software to Mitigate Musculoskeletal Disorders. Results show that the subject is having low back compression force of 672 which is below the NIOSH Back Compression Action Limit of 3400N representing a nominal risk of low back injury.

The influence of bed height as a percentage of participant height on low back forces when boosting a patient up in bed.

Repositioning patients is a frequent task for healthcare workers causing substantial stress to the low back. Patient handling methodologies that reduce low back load should be used. Some studies have observed the effect of bed height on back forces using a limited range of heights. This study details a wider range. The aim of this study was to discover an optimal bed height for reducing low back force when boosting a patient. 11 university students and local residents participated by completing a series of boosts with a 91.6 kg research assistant acting as dependent. The bed was adjusted 3% of participant height and 3 boosts were completed at each height which resulted in 8-10 different bed heights depending on the height of the participant. Motion and force data were collected to estimate low back forces via 3DSSPP. Pearson's R was performed to observe the correlation between caregiver height and low back forces. There were significant negative correlations between bed height and low back compression force at L4-L5 (r = -0.676, p = <0.001) and L5-S1 (r = -0.704, p = <0.001). There were no significant correlations with any shear forces. The highest bed height led to decreased low back compression forces regardless of participant height, but there was not a significant difference in shear forces. Thus, healthcare workers may experience less low back stress with the bed at a higher height. There may be a force tradeoff between the low back and other parts of the body that needs further exploration. Healthcare workers need to be made aware of the implications of adjusting the environment when performing patient handling tasks.

Robust estimation of lumbar joint forces in symmetric and asymmetric lifting tasks via large-scale electromyography-driven musculoskeletal models

Low back joint compression forces have been linked to the development of chronic back pain. Back-support exoskeletons controllers based on low back compression force estimates could potentially reduce the incidence of chronic pain. However, progress has been hampered by the lack of robust and accurate methods for compression force estimation. Electromyography (EMG)-driven musculoskeletal models have been proposed to estimate lumbar compression forces. Nonetheless, they commonly underrepresented trunk musculoskeletal geometries or activation–contraction dynamics, preventing validation across large sets of conditions. Here, we develop and validate a subject-specific large-scale (238 muscle–tendon units) EMG-driven musculoskeletal model for the estimation of lumbosacral moments and compression forces, under eight box-lifting conditions. Ten participants performed symmetric and asymmetric box liftings under 5 and 15 kg weight conditions. EMG-driven model-based estimates of L5/S1 flexion–extension moments displayed high correlation, R2 (mean range: 0.88–0.94), and root mean squared errors between 0.21 and 0.38 Nm/kg, with respect to reference inverse dynamics moments. Model-derived muscle forces were utilized to compute lumbosacral compression forces, which reached eight times participants body weight in 15 kg liftings. For conditions involving stooped postures, model-based analyses revealed a predominant decrease in peak lumbar EMG amplitude during the lowering phase of liftings, which did not translate into a decrease in muscle–tendon forces. During eccentric contraction (box-lowering), our model employed the muscle force–velocity relationship to preserve muscle force despite significant EMG reduction. Our modeling methodology can inherently account for EMG-to-force non-linearities across subjects and lifting conditions, a crucial requirement for robust real-time control of back-support exoskeletons.

Effect of using real motion versus predicted motion as input for digital human modeling of back and shoulder loads during manual material handling

Digital human modeling (DHM) technology is considered the state of the art in designing and evaluating workstations. Previous studies examined the differences between DHM's posture and motion prediction relative to human experimental data. Yet, the effect the two different inputs on biomechanical loads was not assessed. Therefore, this study evaluates the differences in L4/L5 compression force and shoulder torques during a work process calculated using DHM with motion prediction (Jack by Siemens) and DHM with experimental data. The work process is a sequential removing, carrying, and depositing task performed by nine females and nine males and recorded using a motion capture system. The analysis shows that using experimental data results in larger back compression force during the removing task (average 15.4%), similar force during the depositing task (average 0.68%), and less force during the carrying task (19.875%). Using experimental data resulted in larger shoulder torque during all tasks (average 24.97%).

A Lower-Back Exoskeleton With a Four-Bar Linkage Structure for Providing Extensor Moment and Lumbar Traction Force

Lower back pain and related injuries are prevalent and serious problems in various industries, and high compression force to the lumbosacral (L5/S1) region has been known as one of the key factors. Previous research on passive lower back exoskeletons focused on reducing lumbar muscle activation by providing an extensor moment. Additionally, lumbar traction forces can reduce the compression force, and is a common treatment method for lower back pain in clinics. In this paper, we propose a novel passive lower back exoskeleton that provides both extensor moment and lumbar traction force. The working principle of the exoskeleton, extending the coil springs during lumbar flexion, and its design criteria regarding the amount of each force element were provided. The kinematic model explained its operation, and the dynamic simulation estimated its performance and validated its satisfaction with the design criteria. The biomechanical model provided a brief insight into the expected exoskeleton's effect on the reduced lower back compression force. Ten subjects performed static holding and dynamic lifting tasks, and the generated force elements in two directions, parallel and perpendicular to the trunk, were evaluated using a force sensor and electromyography sensors, respectively. The experiment demonstrated a pulling force opposite to the direction of intradiscal pressure and reduced erector spinae activation. This implies the effect of wearing the exoskeleton to decrease the intervertebral pressure during static back bending or heavy lifting tasks.

Factors affecting spine loading in a box lifting task: a digital human modelling study

This paper presents a digital human modelling (DHM) study of a box-lifting task considering human physical characteristics (i.e., gender and percentile) and task requirements (i.e., posture and force). Two response variables are considered: compression force on L4/L5 and the tension on right/left Latissimus Dorsi muscle. Multivariate analysis of variance (MANOVA) was used to analyse the data. Results showed that lower back compression force is positively correlated with Latissimus Dorsi muscle tension (r = 0.94). Moreover, the 95th percentile male in standing position experienced the highest compression force on the lower back; however, both males and females had similar muscle tension.

Ergonomic Assessment of Low Back Loading Pattern During Occupational Lifting Task in a Lower Limb Amputee: Minimizing Injury Risk.

While the relationship between occupational task intensity and repetitive overuse injuries have been well studied and prescription/guidelines to assess and minimize risk of such injuries well established in the general healthy population, these aspects are not well understood in individuals with disabilities. In this practice-oriented paper, we use high a resolution sensor-data driven methodology to track muscle activation patterns and joint kinematics during a common lifting task in a unilateral lower limb amputee to gain a better understanding of the risk of injury during non-optimal lifting postures. The observed data from high resolution sensors are used to recommend optimized prosthetic device tuning. Further the participant specific low back compression loads calculated using Hand-Calculation Back Compressive Force estimation model (HCBCF) and the University of Michigan 3D Static Strength Prediction Program (3DSSPP™) model is used to identify the safe zones of joint loading during the lifting task.

Assessing Psychosocial and Personal Factors in Industrial Work: Issues and Challenges for the Occupational Ergonomics Practitioner and Researcher

The occupational ergonomics practitioner has traditionally focused on physical aspects and risk factors of industrial jobs (e.g., forces exerted, moments and loading on the joints, low back compressive force, upper extremity repetitive motion, etc.). However, some studies have shown that physical risk factors may only account for about 37% of low back pain (Punnett et al., 2005). Psychosocial factors continue to be identified as an important element in the incidence of many occupationally-related musculoskeletal disorders. Some researchers have included assessments of psychosocial and personal/individual factors to biomechanical assessments in studies of occupational injury risks (e.g., Marras et al., 2000, Ferguson et al., 2012). Others (e.g., Barim et al., 2019) have examined incorporating personal/individual factors into risk assessment methods to give a more complete picture of injury risk that an individual or a subgroup of workers (e.g., gender, age, prior injury) may face on jobs. This discussion panel will explore the research in the fields of psychosocial and personal risk factors and their relevance to the assessment of injury risk. This session is relevant for the practitioners who must understand, interpret and apply the results of research to real-world problems.

Exploring the prospective efficacy of waste bag-body contact allowance to reduce biomechanical exposure in municipal waste collection

Municipal waste collectors must avoid bag-body contact, requiring waste bags to be held further from the body. Donning sharps-proof clothing would permit bag-body contact, allowing the bag to be closer to the body, reducing biomechanical exposures. To test this hypothesis, 25 participants loaded waste bags into a simulated garbage truck hopper under two lifting (contact allowed, no contact) and bag mass (7 kg and 20 kg) conditions. Bottom-up rigid-link biomechanical modelling results including peak low back compression force, antero-posterior shear force and peak low back flexion angle were not different between the lifting conditions, but cumulative compression was decreased with bag-body contact, although only at the 20 kg mass. Bag mass had significant effects on outcome measures, causing compression to increase to 4663 (±697) N, exceeding recommended thresholds. Sharps-proof clothing and municipally mandated 23 kg maximum allowable bag mass restrictions may not sufficiently reduce biomechanical exposures to prevent MSD.

Lumbar Forces While Making a Bed With and Without an Instant Tuck™ Mat

Introduction: Conventional wisdom to avoid back pain while making your bed recommends not to lean across your bed to tuck in the sheets, and to keep your back straight and use Core Muscles. This is not practical or possible with any of the many different designs currently available. At present, there is no safe way to make your bed, which can significantly increase the risk of injury and create lifelong disabilities for both individuals and certain professional bedmakers such as house keepers, and caregivers. Objective: It was hypothesized that the use of an Instant Tuck™ Mat can significantly lower the Back-Compression Force (BCF) on the Lower Back and fall far below the risk threshold level stated by the NIOSH. The Instant Tuck™ Mat addresses this major health problem of back pain and injuries by eliminating the need to ever lift a mattress when making the bed. Method: A sample of 35 subjects performed the task of making a bed with a queen-sized mattress with and without the Instant Tuck™ Mat in a random order. BCF, the number of lifts to make the bed as well as the length of time for each lift, and the number of times each individual bent forward was measured during each trial. Results: There were significant differences for all the measured variables. Regarding the BCF, there was an approximately 85% reduction of pressure on the lower back when using the Instant Tuck™ Mat vs. not using it, which was a highly significant decrease (p&lt;.001). Also, the number of times the mattress was lifted was lower by 12 times when using the Instant Tuck™ Mat vs. not using it (p&lt;.001). Finally, the times each individual bent down was approximately 9 times less when using the Instant Tuck™ Mat vs. not using it (p&lt;.001). Conclusion: BCF’s making a bed in its current form is by a wide margin out of compliance with NIOSH standards and as a result it poses a significant risk of injury especially for those who are required to perform this for their occupation, such as hotel housekeepers and hospital, nursing home, and in-home caregivers. Making a bed using the Instant Tuck™ Mat reduced the BCF’s by 85% and is in line with NIOSH standards. The Instant Tuck™ Mat has that it can make the repetitive act of making a bed safe and that it can significantly reduce the risk of injury based on NIOSH standards.

Factors Affecting Spine Loading in a Box Lifting Task: A Digital Human Modeling Study

This paper presents a digital human modelling (DHM) study of a box-lifting task considering human physical characteristics (i.e., gender and percentile) and task requirements (i.e., posture and force). Two response variables are considered: compression force on L4/L5 and the tension on right/left Latissimus Dorsi muscle. Multivariate analysis of variance (MANOVA) was used to analyse the data. Results showed that lower back compression force is positively correlated with Latissimus Dorsi muscle tension (r = 0.94). Moreover, the 95th percentile male in standing position experienced the highest compression force on the lower back; however, both males and females had similar muscle tension.

Does Wearable Crutch Walking Excessively Load the Hip Joint?

PURPOSE: As an alternative to using traditional axillary crutches for non-weightbearing, the use of a wearable crutch has been associated with better functional outcomes. However, hip and back pain have been reported as side effects. This may be due to the reduced ability of the lower extremity to attenuate ground reaction forces. The primary objective was to compare compressive forces at the hip between wearable crutch walking, normal walking and axillary crutch walking. It was hypothesized that hip forces would be higher with wearable crutch walking compared with normal walking and axillary crutch walking. METHODS: Three-dimensional kinematics and ground reaction forces were measured in 12 healthy subjects (11 men, 1 woman, age 36±10 yr) during normal gait, axillary crutch ambulation and wearable crutch walking (iWalk 2.0). Hip and trunk range of motion, as well as peak vGRF and peak hip and low back compressive force during the stance phase, were compared for the three conditions using repeated-measures ANOVA. RESULTS: Gait speed while wearing the wearable crutch was reduced 44% compared to normal gait and 33% compared to crutch ambulation (P < 0.001). Frontal and sagittal plane hip range of motion were both significantly reduced during both crutch conditions compared to normal gait (P<0.001). Trunk range of motion in both planes was greatest during wearable crutch walking compared to both normal gait and crutch ambulation (P<0.001). Peak vGRF while wearing the hands-free crutch was 12% lower than normal gait (P<0.001) and 30% lower than crutch ambulation (P<0.001). Peak compressive hip force during wearable crutch walking was 11% lower than during normal walking (P = 0.026) and 30% lower than during axillary crutch walking (P<0.001). Low back compressive force during wearable crutch walking was 18% higher than during normal walking (P=0.03) but not different than during axillary crutch walking (1.4 % difference P>0.05) CONCLUSIONS: Despite a reduction in the shock-absorbing ability of the lower extremity, vGRF and compressive hip forces were not increased during wearable crutch walking. Although low back compressive force did increase with this device, it did not exceed the forces during axillary crutch walking. Therefore, the wearable crutch seems to be safe for patients who are required to be non-weightbearing.

Evaluation of the Back Compressive Force (BCF) using the UTAH Method in Manual Handling Tasks among Workers of a Chemical Manufacturing Company

Introduction: Job back pain is one of the most common occupational diseases and injuries in the world that affects people's physical and mental health. The purpose of this study was to evaluate the BCF using the UTAH method in manual handling tasks among workers of a chemical manufacturing company.Methods: This descriptive and cross-sectional study was carried out on 35 people who had manual handling tasks and worked in a chemical factory in April and May 2018. The participants were selected using the simple random sampling method. In this study, UTAH method and standard Cornell questionnaire were used to collect the data. Finally, we run descriptive statistics and ANOVA test to analyze the data using the SPSS19.Results: The average amount of BCF calculated using the UTAH method showed that the load pressure on back for the jobs of repair unit (400 kg), discharge and loading unit (460 kg), and warehouse unit (370 kg) exceeded the standard. Moreover, the results of the Cornell questionnaire indicated that 68 percent (N = 24) of individuals in the mentioned occupations were suffering from lower back pain.Conclusion: The findings of this study showed that the UTAH method is useful for estimating the BCF in manual handling tasks. We also found that 68 percent of the participants had occupational back pain. So, interventions should be conducted and measures should be taken to reduce these disorders.

Back Compressive Force (BCF) assessment using UTAH method in manual handling tasks among workers of a chemical manufacturing company

Back Compressive Force (BCF) assessment using UTAH method in manual handling tasks among workers of a chemical manufacturing company

Ergonomic evaluation of standard and alternative pallet jack handless

AimTransportation of materials using a pallet jack pulled behind the operator is common due to the visual advantages while transporting fully loaded pallets. The objective of this laboratory study was to quantify muscle activity, posture, and low back compressive and shear forces while completing typical pallet jack activities using a standard handle that required one handed pulling of a pallet jack compared to an alternative handle that allowed for two handed pushing. MethodsParticipants (n = 14) performed six to ten trials of common pallet jack tasks (straight travel and turning) with each handle. Posture analysis of the trunk and right upper extremity was performed using Motion Analysis (Santa Rosa, CA, USA) and back compressive and shear forces were analyzed using 3D Static Strength Prediction Program (University of Michigan, Ann Arbor, MI). Activity of the upper trapezius (UT), pectoralis major (PM), flexor digitorum superficialis (FDS) and extensor digitorum (ED) muscles were recorded (Telemyo 2400 T, Noraxon, Scottsdale, Arizona) and normalized to percent reference voluntary contraction values. All outcomes were compared using the paired t-test. ResultsPeak and mean muscle activity of the PM (p < 0.001) and ED (p < 0.01) were significantly higher using the alternative push handle during all three tasks. There were larger compressive forces at L4/L5 (p < 0.08) and L5/S1 (p < 0.002) using the alternative handle, and greater shear forces using the standard handle at both L4/L5 (p < 0.0001) and L5/S1 (p < 0.000). DiscussionThe standard handle outperformed the alternative handle with regard to muscle activity. The alternative handle had significantly greater compressive forces at L5/S1 due to the pushing nature of the hand-handle interface, yet the standard handle increased shear forces at both L4/L5 and L5/S1 levels in the low back. ConclusionIn this analysis, there was not a clear benefit to using either handle in terms of trunk strength capacity and varied benefits and drawbacks to each handle when comparing compressive and shear forces in the low back. However, given favorable subjective reports described in a prior publication, and the increased reliance on dynamic versus passive force production, facilitating a workers' ability to push a pallet jack while travelling with large loads is worth further investigation.

Effect of pelvic forward tilt on low back compressive and shear forces during a manual lifting task.

[Purpose] To examine the effect of an instruction to increase pelvic forward tilt on low back load during a manual lifting task in the squat and stoop postures. [Subjects] Ten healthy males who provided informed consent were the subjects. [Methods] Kinetic and kinematic data were captured using a 3-dimensional motion analysis system and force plates. Low back compressive and shear forces were chosen as indicators of low back load. The subjects lifted an object that weighed 11.3 kg, under the following 4 conditions: squat posture, stoop posture, and these lifting postures along with an instruction to increase pelvic forward tilt. [Results] In the squat posture, the instruction to increase pelvic forward tilt reduced the low back compression and shear forces. [Conclusion] The present results suggest that a manual lifting task in the squat posture in combination with an instruction to increase pelvic forward tilt can decrease low back compression and shear forces, and therefore, might be an effective preventive method for low back pain in work settings.

Using Peak Vicon data to drive Classic JACK animation for the comparison of low back loads experienced during para-rowing

The use of kinematic data collected from subjects in a Vicon laboratory can be used to generate human motion within the Classic JACK simulation environment. This feature is primarily used in the ergonomic design of equipment that the human must interact with. In this case, the research was evaluating the estimated low-back joint force while rowing in one of three para-rowing setups. This paper describes the method by which Vicon data were recorded, smoothed, imported and applied to the JACK manikin to produce realistic rowing animations. It also describes how the kinetic information from a load cell placed in-line with the ergometer chain was recorded, conditioned and applied to the virtual hands of the JACK manikin to improve the force estimates of the lower back. The low back compressive forces estimated by the Classic JACK program are compared to the NIOSH occupational limits as a point of reference. Findings suggest that males, but not females, rowing in the trunk and arms category were significantly above the NIOSH action limit. Females rowing in the arm and shoulder category were significantly below the NIOSH action limit. Future work will evaluate how design features of the para-rowing setup might be altered to reduce joint loading.

1B2-1 持ち上げ動作によって生じる椎間板圧縮力の比較

1B2-1 持ち上げ動作によって生じる椎間板圧縮力の比較

Effect of Mental Processing on Low Back Load While Lifting an Object

Biomechanical study using a 3D motion analysis system conducted in a laboratory setting. To determine the effect of mental processing on low back load during lifting. In addition to ergonomic factors such as frequent lifting, work-related psychosocial factors are significant in the onset of disabling back pain. Although the ergonomic effects on low back load while lifting have been investigated and are widely accepted in the workplace, few studies have investigated the effect of psychosocial factors on low back load while lifting. Thirteen healthy subjects lifted a box from the ground in 4 different lifting tasks in randomized order: (1) squat posture with knees flexed; (2) stoop posture with knees extended; (3) squat posture with mental processing using arithmetic tasks; and (4) stoop posture with mental processing using arithmetic tasks. We used a 3D motion analysis system and 4 force plates to record kinematic and kinetic data. We calculated dynamic triaxial low back joint moments and low back compression force as index parameters of low back load under these experimental conditions. Mental processing significantly increased peak low back compression force and low back extension moment, but not lateral flexion or rotation moment, while lifting in both lifting postures. Also, mental processing increased trunk bending angles in the squat posture. Although a tendency for decreased pelvic forward tilt was observed, mental processing did not significantly decrease forward pelvic tilt in the stoop posture. Mental processing during lifting tasks seems to affect both trunk and pelvis angles in the sagittal plane for squat and stoop postures, resulting in increased low back load. The present findings might help explain the effect of ergonomic demands of lifting tasks as well as psychosocial factors responsible for the onset of disabling back pain. 2.

The Effect of Lifting Speed on Cumulative and Peak Biomechanical Loading for Symmetric Lifting Tasks

BackgroundTo determine the influence of lifting speed and type on peak and cumulative back compressive force (BCF) and shoulder moment (SM) loads during symmetric lifting. Another aim of the study was to compare static and dynamic lifting models.MethodsTen male participants performed a floor-to-shoulder, floor-to-waist, and waist-to-shoulder lift at three different speeds [slow (0.34 m/s), medium (0.44 m/s), and fast (0.64 m/s)], and with two different loads [light (2.25 kg) and heavy (9 kg)]. Two-dimensional kinematics and kinetics were determined. A three-way repeated measures analysis of variance was used to calculate peak and cumulative loading of BCF and SM for light and heavy loads.ResultsPeak BCF was significantly different between slow and fast lifting speeds (p < 0.001), with a mean difference of 20% between fast and slow lifts. The cumulative loading of BCF and SM was significantly different between fast and slow lifting speeds (p < 0.001), with mean differences ≥80%.ConclusionBased on peak values, BCF is highest for fast speeds, but the BCF cumulative loading is highest for slow speeds, with the largest difference between fast and slow lifts. This may imply that a slow lifting speed is at least as hazardous as a fast lifting speed. It is important to consider the duration of lift when determining risks for back and shoulder injuries due to lifting and that peak values alone are likely not sufficient.