Publication statistics
Pub. period:1987-2012
Pub. count:34
Number of co-authors:52
Co-authors
Number of publications with 3 favourite co-authors:
Sue A. Ferguson:7Steven A. Lavender:5Riley E. Splittstoesser:5 Productive colleagues
William S. Marras's 3 most productive colleagues in number of publications:
Waldemar Karwowski:35Sara J. Czaja:30Steven A. Lavender:17
“
The theory gives the answers, not the theorist.
”
-- Allen Newell
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William S. Marras
Personal Homepage:
ise.osu.edu/ISEFaculty/marras/marras.htm#publications
Publications by William S. Marras (bibliography)
Gielo-Perczak, Krystyna, Karwowski, Waldemar, Hancock, Peter A., Marras, William S., Karwowski, Waldemar, Bonato, Paolo and Gielo-Perczak, Krystyna (2012): Multidisciplinary Concepts in Ergonomic Design and Individual Differences in Performance. In: Proceedings of the Human Factors and Ergonomics Society 2012 Annual Meeting 2012. pp. 1034-1038.
“Currently, individual differences are considered to be the most important factors in home-, work-, health- (HWH) related comfortable designs. However in reality, these factors are still abandoned. Future prospective design needs require an intensive multidisciplinary approach to individual differences and performance capacities. The purpose of this panel is to discuss controversial concepts and ideas on individual differences and capacities which should be included in HWH designs. Novel designs necessitate a broad interaction among psychology, physiology, sociology, biomechanics, emerging current health care needs and functional design as an integration of the individual differences within human capabilities and daily necessities.”
© All rights reserved Gielo-Perczak et al. and/or Human Factors and Ergonomics Society
Davis, Kermit G., Marras, William S., Punnett, Laura, Winkelstein, Beth and Blatter, Birgitte (2012): Underlying Factors of Musculoskeletal Disorders: What Are We Missing?. In: Proceedings of the Human Factors and Ergonomics Society 2012 Annual Meeting 2012. pp. 1128-1129.
“The purpose of the panel will be to discuss briefly the current knowledge of factors relating to musculoskeletal disorders in four main areas: biomechanics, psychosocial, individual characteristics, and pain sensation. The main discussion of the panel will have panelist challenge musculoskeletal disorder researchers to focus on new directions and think beyond current paradigms.”
© All rights reserved Davis et al. and/or Human Factors and Ergonomics Society
Marras, William S., Wanchisen, Barbara, Czaja, Sara J., Gibbons, Chris, Mathews, Judith and Story, Molly (2011): National Research Council Board on Human-Systems Integration Special Panel Session: Human Factors and Home Health Care. In: Proceedings of the Human Factors and Ergonomics Society 55th Annual Meeting 2011. p. 614.
“Health care is increasingly occurring in home settings rather than in professional medical settings, and consumers are expected to engage in a wide range of health-care tasks using wide varieties of technology and equipment. The Board on Human-Systems Integration (BOHSI) at the National Research Council (NRC) recently provided oversight on a study funded by the Agency for Health Care Research and Quality to examine the current state of health care in the home and identify existing problems and opportunities for improvement of care through the application of human factors/ergonomics knowledge and methods. This panel will present the highlights of the findings of that study, and panelists will discuss the increasingly important role of human factors engineering within home health care.”
© All rights reserved Marras et al. and/or HFES
Ferguson, Sue A., Splittstoesser, Riley E. and Marras, William S. (2011): Differences between Physicians in Lumbar MRI Measures. In: Proceedings of the Human Factors and Ergonomics Society 55th Annual Meeting 2011. pp. 733-737.
“The purpose of this study was to quantify inter-rater reliability when measuring spinal structure dimensions on magnetic resonance imaging (MRI) scans. A new open MRI machine was available that allowed patients be recumbent, sitting or standing during an MRI of the spine. A total of 39 low back pain patients were scanned for the study. Patients were scanned in seven postures including recumbent, sitting neutral, flexed, extended, standing neutral, flexed, and extended. Two medical professionals trained in neurosurgery were asked to make measurements on the lumbar spine scans. The scans included 22 axial slices and 14 sagittal view slices. At best the two physicians chose the same slice to evaluate on the MRI in 27 of 39 cases (69%). This study illustrates the differences between physicians when evaluating lumbar spine MRI as well as the subjective nature of medical decision making.”
© All rights reserved Ferguson et al. and/or HFES
Davis, Kermit G., Kotowski, Susan E. and Marras, William S. (2011): Mechanical Power-Drive Reduces the Stress on the Back. In: Proceedings of the Human Factors and Ergonomics Society 55th Annual Meeting 2011. pp. 984-987.
“Nursing continues to be an occupation that experiences high levels of low back and shoulder injuries. Transferring patients in a bed or stretcher is one potential handling task that could lead to back injuries. The loads on the back could potentially be reduced by utilizing a power-drive intervention and was the focus of the current study. Twelve participants completed the transferring conditions utilizing a general hospital bed and stretcher with and without power-drive. The peak and cumulative three-dimensional spine loads were”
© All rights reserved Davis et al. and/or HFES
Splittstoesser, Riley E., Knapik, Greg G. and Marras, William S. (2011): A Simple Model of Changes in Lumbar Intervertebral Angles During Sagittal Torso Flexion. In: Proceedings of the Human Factors and Ergonomics Society 55th Annual Meeting 2011. pp. 1029-1033.
“Objective: To create simple models of intervertebral angle that account for subject anthropometry and are simple to apply within biomechanical models. Background: Biomechanical models require accurate intervertebral angle data if they are to correctly partition calculated forces into compression and shear. Current intervertebral angle models either require extensive instrumentation or were developed using limited subject populations. Methods: MRI images were collected from 13 males and 13 females in a series of sagittally flexed postures. Measured intervertebral angles and anthropometry were used to create linear regression equations of the L5/S1 through T12/L1 motion segments. Results: The models are predictive of posture related intervertebral angle changes. Conclusions: Models of intervertebral angle developed here require simple measures that allow accurate prediction of changes in intervertebral angles that can be used in biomechanical models for predicting forces acting on the lumbar spine.”
© All rights reserved Splittstoesser et al. and/or HFES
Splittstoesser, Riley E., Marras, William S. and Best, Thomas M. (2011): Spinal Loading and Immune Responses to Personality and Mental Load During Repetitive Lifting. In: Proceedings of the Human Factors and Ergonomics Society 55th Annual Meeting 2011. pp. 1034-1038.
“Objective: Investigate effects of interactions between biomechanical, psychosocial and individual risk factors on spinal loading and inflammatory responses. Background: Current low back pain causation theories do not explain the difficulty making specific diagnoses based on low back imaging. Methods: Two groups of subjects possessing sensor or intuitor personality trait performed repetitive lifting with high or low mental workload. Spinal loading was assessed using a biomechanical model and immune markers were collected before and after lifting. Results: Mental loading was associated with a decrease in AP shear. Both exposure conditions were characterized by a time-regulate immune response evidenced by markers of inflammation, tissue trauma and muscle damage. Intuitors CK levels increased over sensors following the low mental workload condition but not for the high mental workload condition. Conclusions: An immune response exists to lifting and mental loading that is influenced by personality and mental workload.”
© All rights reserved Splittstoesser et al. and/or HFES
Ferguson, Sue A., Allread, W. Gary, Le, Peter, Rose, Joseph D. and Marras, William S. (2011): Shoulder Muscle Oxygenation during Repetitive Tasks. In: Proceedings of the Human Factors and Ergonomics Society 55th Annual Meeting 2011. pp. 1039-1041.
“The purpose of this study was to quantify shoulder muscle oxygenation during repetitive shoulder exertions that were similar to motions found in automobile assembly tasks. Ten subjects participated in the study. There were three independent variables: 1) shoulder flexion angle; 2) frequency; and 3) force. The dependent measure was percentage change in muscle oxygenation for the anterior deltoid and trapezius. The results showed significant muscle oxygenation decreases for each of the main effects (shoulder flexion angle, frequency and force). The interaction of force and repetition was significant for the anterior deltoid, indicating that, as repetition increased the magnitude of the differences between the force levels increased. The interaction of repetition and shoulder angle was also significant. The results of this research illustrate that ergonomists need to consider the interaction of injury risk factors that may trigger musculoskeletal disorders of the shoulder.”
© All rights reserved Ferguson et al. and/or HFES
Marras, William S. (2010): BORED BEYOND BELIEF: HOW AUTOMATION IS BORING US TO DISTRACTION. In: Proceedings of the Human Factors and Ergonomics Society 54th Annual Meeting 2010. p. 758.
“The inclusion of automation has been critical for increased safety and efficiency in complex systems such as aviation and process control, but one unintended consequence for human operators is boredom. In many phases of operation (i.e., en-route flight over the Atlantic and full-power nuclear power plant operations), operators are monitoring interfaces, waiting for the unlikely system anomaly. Such highly automated environments require levels of vigilance that are difficult for operators to maintain, and resulting boredom increases the likelihood of operator distraction, which ultimately can affect system performance if operators miss or respond late to critical events. This presentation will highlight the problems of sustained attention and boredom in highly automated environments. Panelists will discuss areas of future research as well as review other efforts of the Committee on Human-Systems Integration.”
© All rights reserved Marras and/or HFES
Ferguson, Sue A., Marras, William S., Allread, W. Gary, Knapik, Gregory G., Vandlen, Kimberly A., Splittstoesser, Riley and Yang, Gang (2009): Musculoskeletal Disorder Risk Associated with Auto Rotation Angle during an Assembly Task. In: Proceedings of the Human Factors and Ergonomics Society 53rd Annual Meeting 2009. pp. 874-878.
“The purpose of this study was to quantify how musculoskeletal disorder exposure risk changes in an auto assembly task as a function of car body rotation. Twelve subjects participated in the study. There were three car body angles including 1) zero or standard, 2) forty-five degrees and 3) ninety degrees from horizontal. Musculoskeletal exposure included spine loads, spine posture, shoulder posture, neck posture and wrist posture, as well as normalized electromyography of the shoulder and neck. The results showed that musculoskeletal disorder exposure risk decreased as the car was rotated to forty-five degrees and further decreased as the car was rotated to ninety degrees. Thus, rotating the car body reduces musculoskeletal exposure which in turn may reduce the risk of musculoskeletal disorders. It should be noted that the results may vary with other assembly tasks.”
© All rights reserved Ferguson et al. and/or their publisher
Marras, William S., Lavender, Steven A., Ferguson, Sue A., Splittstoesser, Riley E. and Yang, Gang (2009): Dynamic Load Moment Exposure and Spine Function Impairment. In: Proceedings of the Human Factors and Ergonomics Society 53rd Annual Meeting 2009. pp. 879-881.
“A prospective study was performed in distribution center environments in order to determine which physical exposure measures related to a reduction in low back function. Workers in 50 distribution jobs employed in 21 distribution centers were monitored over at least a 6 month period for changes in spine function. Job exposures were monitored with a sonic-based exposure tracking system (laboratory in a backpack) that captured 197 physical exposure metrics per lift. Based upon the database containing over 60,000 lifts, a multivariate model was developed capable of predicting jobs characteristics associated with a decrement in spine function over time. The sensitivity and specificity of the”
© All rights reserved Marras et al. and/or their publisher
Lavender, Steven A., Marras, William S., Ferguson, Sue A., Splittstoesser, Riley E., Yang, Gang and Schabo, Pete (2009): Identifying Safe Load Moment Exposures for the Back. In: Proceedings of the Human Factors and Ergonomics Society 53rd Annual Meeting 2009. p. 883.
“Low back disorders continue to be the most common and significant work-related musculoskeletal disorders in the US. Identifying what constitutes a "safe" physical workload has been the biggest challenge facing injury prevention efforts. Prior low back injury risk models have focused on manufacturing activities where there is limited variability in the parameters used to describe the exposures to low back disorder risk factors. Lifting tasks in distribution centers can have considerably more variability in load and physical layout. The goal of this project was to identify and quantify measures that characterize the biomechanical risk factors, including measures of the load moment exposure, and measures that characterize the duty cycle that are predictive of low back disorders in distribution centers. Thus, our hypothesis was that we could define a relationship between moment exposure parameters and the low back disorder incidence rates. A cross-sectional study was designed to examine the mechanical risk factors responsible for reported low back injury in distributions centers. The physical exposure was measured on 195 workers on 50 jobs in 21 distribution centers using a sonic-based Moment Exposure Tracking System (METS). The METS measures load, force, load moment, torso kinematics, and temporal parameters of the job simultaneously. For each job, low back injury rates were collected retrospectively from the company's records over the prior 3-year period. The data were used to develop a risk model designed to predict back injury risk based upon direct measures of load and load moment exposure. The model incorporates biomechanical variables which include the load moment and horizontal sliding forces, as well as a temporal variable indicating the opportunity for micro-breaks during the work process. Overall, the”
© All rights reserved Lavender et al. and/or their publisher
Granata, Kevin P. and Marras, William S. (1995): A Biomechanical Assessment of Axial Twisting Exertions. In: Proceedings of the Human Factors and Ergonomics Society 39th Annual Meeting 1995. pp. 600-604.
“Axial twisting of the torso has been identified as a significant risk factor for occupationally related low-back disorders. The purpose of this investigation was to examine the influence of dynamic twisting parameters upon spinal load. Measured trunk moments and muscle activities were employed in a biomechanical model to determine loads on the lumbar spine. Spinal loads were examined as a function of dynamic torsional exertions under various conditions of force, velocity, position, and direction. Results demonstrate significant flexion-extension and lateral moments were generated during the twisting exertions. Muscle coactivity was significantly greater than equivalent levels measured during sagittal lifting exertions. Relative spinal compression during dynamic twisting exertions was twice that of static exertions. Spine loading also varied as a function of whether the trunk was twisted to the left or right, and the direction of applied torsion, i.e. clockwise versus counter-clockwise. The results may help explain, biomechanically, why epidemiological findings have repeatedly identified twisting as a risk factor for low-back disorder.”
© All rights reserved Granata and Marras and/or Human Factors Society
Sommerich, Carolyn M., Marras, William S. and Parnianpour, Mohamad (1995): Activity of Index Finger Muscles during Typing. In: Proceedings of the Human Factors and Ergonomics Society 39th Annual Meeting 1995. pp. 620-624.
“An electromyographic investigation was conducted of finger and wrist muscle activity during typing. Examination of the data revealed substantial activity of the extrinsic extensor, a muscle which is ignored in many existing biomechanical finger models. This paper describes activity of the extensor muscle during typing, in absolute terms and relative to activity of the extrinsic flexors. Amplitude probability distribution analyses demonstrated that static extensor activity exceeded 5% MVC for all subjects. Two subjects exhibited pronounced patterns of coactivity in the extrinsic extensor and flexor muscles. Biomechanical modeling efforts demonstrated similar force contributions from the extrinsic extensors and flexors. Based on these results, neglect of finger extensor activity would result in underestimation of finger joint loading.”
© All rights reserved Sommerich et al. and/or Human Factors Society
Kim, Jung-Yong, Parnianpour, Mohamad and Marras, William S. (1995): Development of Experimental Protocol to Quantitatively Assess the Neuromuscular Control Capability of Low-Back Pain Patients. In: Proceedings of the Human Factors and Ergonomics Society 39th Annual Meeting 1995. pp. 754-758.
“An experimental protocol was developed in this study in order to quantify the control capability of the trunk movement for LBP patients. Fitts' law (1954) was employed to measure the dynamic performance parameters such as flexion/extension velocity and acceleration with controlled ROM and the information processing capacity (bits/second) of the trunk. A series of statistical analyses were performed to reduce the length of protocol for clinical application; 11 indices of difficulty (ID=log{sub:2}(2A/W), A: ROM, W: target tolerance) used by Kim et al. (1993, 1994) were shortened into 3 ID conditions. The accuracy of the protocol was validated by comparing those two conditions: 3 IDs and 11 IDs. This clinical protocol was also adjusted to test patients with ROM from 20 degrees to 40 degrees and above. This final short experimental protocol can be used to evaluate the neuromuscular performance of LBP patients with a minimal discomfort.”
© All rights reserved Kim et al. and/or Human Factors Society
Fathallah, Fadi A. and Marras, William S. (1995): Spinal Coupled Motions and Their Association with the Risk of Low Back Disorders in Industrial Tasks. In: Proceedings of the Human Factors and Ergonomics Society 39th Annual Meeting 1995. p. 959.
“Occupational low back disorders (LBDs) have been responsible for a great deal of human suffering while imposing a tremendous financial burden on the affected individuals, their employers, and the health insurance providers. Several epidemiological and in-vitro studies have implicated Combined motions and loads of the back to constitute highly undesirable lifting situations. However, up to this date, there were no studies that quantitatively assessed trunk coupled or combined motions of industrial workers. Therefore, the main purpose of this study was to quantify the simultaneous multi-dimensional coupled motions (velocities) of the trunk in various manual materials handling (MMH) jobs with varying degrees of LBD risk. The results showed that representing information in a continuous multivariate space revealed information that would be otherwise obscured in a univariate dimension. In addition, there seem to be a threshold of sagittal bending where, if surpassed, dynamic coupled motions were most pronounced in high and medium risk groups. The results were in agreement with empirical findings that showed how coupled situations similar to the ones observed in this study may have adverse effects on the spinal structure. Investigating, in details, the role of combined dynamic risk factors help the process of comprehending low back injury mechanism, and abating LBDs in industrial settings.”
© All rights reserved Fathallah and Marras and/or Human Factors Society
Lehman, Katherine R. and Marras, William S. (1994): The Effects of Human Interface Design on Wrist Biomechanics during Scanning. In: Proceedings of the Human Factors and Ergonomics Society 38th Annual Meeting 1994. pp. 616-620.
“Two window, or "bi-optic" scanners have ergonomic potential to minimize cumulative trauma disorders (CTDs) among grocery checkers. However, not all checkers utilize both windows when scanning. Four, two window scanners were tested to see whether the number of windows used had an effect on wrist acceleration, one of the most predictive indicators of CTD risk. Out of 32 subjects, 14 used only one window while scanning. These subjects were seen to have significantly higher cumulative peak wrist accelerations than those subjects that used both windows. In addition, the productivity of the one window users was significantly lower than two window users. The results indicate that two window scanners can not only increase productivity, but can reduce the risk of CTDs. However, this will only occur if checkers appreciate and choose to use both windows in their scanning activity. The large number of subjects (14 out of 32) that only used one window when scanning indicates a serious human interface problem with these types of scanners. This paper identifies the need for better scanner designs that will indicate to the user the three-dimensional scan zone created by the two windows. The design should influence one to use both windows while scanning so that wrist motions will be reduced. Most importantly, this paper identifies the importance of the relationship between cognitive and biomechanical issues when approaching a human interface problem in a product's design.”
© All rights reserved Lehman and Marras and/or Human Factors Society
Shoenmarklin, Richard W. and Marras, William S. (1993): Wrist Motions in Industry: Variance between Jobs and Subjects. In: Proceedings of the Human Factors and Ergonomics Society 37th Annual Meeting 1993. pp. 649-653.
“Ergonomists assume that they can design out injurious postures and motions with engineering controls by guiding the worker to use the preferred, less injurious motions. The variance between workers performing tasks in ergonomically-designed jobs is assumed to be dominated by the variance between jobs. However, little research exists that quantified whether this assumption is valid. The present study examined the wrist motions of 40 industrial workers who performed highly repetitive, hand-intensive jobs of low and high risk of cumulative trauma disorders (CTDs). The position and angular velocity and acceleration of these workers' wrists were measured in all three planes (radial/ulnar, flexion/extension, pronation/supination) with goniometry. The results of this study show that for all the kinematic variables, the variance between subjects within jobs accounted for a substantial, and often majority, amount of variance. The results of this study demonstrate that ergonomists should consider the variability in motion patterns between workers when designing existing or new jobs and also should monitor at least two subjects per job in quantitative surveillance studies of wrist motion.”
© All rights reserved Shoenmarklin and Marras and/or Human Factors Society
Fathallah, Fadi A., Wright, Patrick L. and Marras, William S. (1993): Variation in Trunk Mobility throughout the Work Day. In: Proceedings of the Human Factors and Ergonomics Society 37th Annual Meeting 1993. pp. 664-668.
“Low back disorders have been a major concern for both industries and the public in general. Diurnal variation in trunk flexibility has been previously observed and quantified in terms of range of motion. It was hypothesized that decreased disc height as the day progresses allows the spinal ligaments to slacken, resulting in an increase in the range of motion (flexibility) and possible reduction in risk of injury. Evidence suggests that this risk may be accentuated under dynamic motions of the spine. This experiment focused on observing the change in dynamic components of trunk flexibility (trunk mobility) as a function of time of the day. Trunk motions of twenty-one male participants were obtained at three specific times of the day using a tri-axial electrogoniometer. No variation in trunk range of motion in any of the cardinal planes was observed. However, velocity and acceleration in the sagittal plane showed significant variations, suggesting the re-examination of the "slack ligaments" hypothesis. This study asserts that identifying flexibility by only its static component, range of motion, gives only partial information. Industrial injuries occurring in the early morning hours may be a result of insufficient trunk mobility. The relation between trunk mobility and back injury incidence rates should be further investigated.”
© All rights reserved Fathallah et al. and/or Human Factors Society
Karwowski, Waldemar and Marras, William S. (1993): A Catastrophe Theory-Based Model for Quantification of Risk of Low Back Disorders at Work. In: Proceedings of the Human Factors and Ergonomics Society 37th Annual Meeting 1993. pp. 683-687.
“This paper discusses applications of the catastrophe theory in the dynamic modeling of occupational low back disorders, and offers a framework for conceptualization of such disorders in view of the elementary cusp catastrophe models. It was proposed that low back disorders due to manual lifting should be considered as a discontinuous phenomenon, reflecting dynamic changes in the state of human musculoskeletal system, which are dependent upon the combination of human strength abilities, muscular fatigue and endurance, spinal loading tolerance, as well as dynamic equilibrium between these variables. The behavior of the proposed cusp-catastrophe based model for the risk of LBDs due to manual lifting jobs was examined based on empirical data collected in industry.”
© All rights reserved Karwowski and Marras and/or Human Factors Society
Ferguson, Sue A., Fathallah, Fadi A., Granata, Kevin P., Kim, Jung Y. and Marras, William S. (1993): Coactivity Effects upon Carpal Tunnel Contact Forces. In: Proceedings of the Human Factors and Ergonomics Society 37th Annual Meeting 1993. pp. 705-709.
“Contact force on the carpal tunnel structures due to flexor tendon forces have been identified as an important contributor to the compression of the median nerve. Therefore, a pilot study was conducted to assess the increase ln carpal contact force due to the antagonistic coactivity of the finger extensor muscles. Surface EMG activities of the superficial finger flexor and extensor muscles of four subjects were measured during several isometric power grip exertions at seven different wrist angles. The results showed that a linear relation between EMG and muscle force holds under the prescribed isometric conditions. An EMG-assisted model was developed to predict tensile forces in an equivalent flexor tendon. For a given angle, the model predicts increased tensile force in the flexor tendon with increased extensor (antagonist) coactivity in response to isometric grip exertions. It was found that if one accounts for muscle coactivity, predisted force in the flexor tendons would be as much as 33% greater than force predicted by models which neglect coactivity. This increase would also be observed in carpal contact force since this force is linearly related to the flexor tendon force. Models that neglect coactivity severely underestimate flexor tendon forces and consequently contact forces in the carpal tunnel.”
© All rights reserved Ferguson et al. and/or Human Factors Society
Lehman, Katherine R., Allread, W. Gary, Wright, P. Lawrence and Marras, William S. (1993): Quantification of Hand Grip Force under Dynamic Conditions. In: Proceedings of the Human Factors and Ergonomics Society 37th Annual Meeting 1993. pp. 715-719.
“A laboratory experiment was conducted to determine whether grip force capabilities are lower when the wrist is moved than in a static position. The purpose was to determine the wrist velocity levels and wrist postures that had the most significant effect on grip force. Maximum grip forces of five male and five female subjects were determined under both static and dynamic conditions. The dominant wrist of each subject was secured to a CYBEX II dynamometer and grip force was collected during isokinetic wrist deviations for four directions of motion (flexion to extension, extension to flexion, radial to lunar, and ulnar to radial). Six different velocity levels were analyzed and grip forces were recorded at specific wrist positions throughout each range of movement. For flexion-extension motions, wrist positions from 45 degrees flexion to 45 degrees extension were analyzed whereas positions from 20 degrees radial deviation to 20 degrees ulnar deviation were studied for radial-ulnar activity. Isometric exertions were also performed at each desired wrist position. Results showed that, for all directions of motion, grip forces for all isokinetic conditions were significantly lower than for the isometric exertions. Lower grip forces were exhibited at extreme wrist flexion and extreme radial and ulnar positions for both static and dynamic conditions. The direction of motion was also found to affect grip strength; extension to flexion exertions produced larger grip forces than flexion to extension exertions and radial to ulnar motion showed larger grip forces than ulnar to radial deviation. Although, males produced larger grip forces than females in all exertions, significant interactions between gender and velocity were noted.”
© All rights reserved Lehman et al. and/or Human Factors Society
Fisher, Donald L., Andres, Robert O., Buchholz, Bryan, Hughes, Richard and Marras, William S. (1992): Applications of Optimization in Biomechanics: Consensus and Controversy. In: Proceedings of the Human Factors Society 36th Annual Meeting 1992. pp. 722-723.
“Increasingly, optimization is appearing as an integral part of biomechanical solutions to ergonomic problems. The primary objective of this panel is to introduce several different optimization tools and point out their related strengths and weaknesses. Optimization techniques have been used to solve a wide range of ergonomic problems. These problems include those which prove the most costly of the occupationally related disorders (in particular, lower back disorders) and those which are the most frequently reported of the occupationally related disorders (in particular, repetitive motion disorders). The problems addressed by this panel will include the above two disorders as well as several related ones. Specifically, mention will made of both lower back disorders (Marras) and repetitive motion disorders (Fisher) as well as slips and falls (Andres), mechanical trauma to the upper extremities (Buchholz), and more general problems requiring the determination of muscle forces (Hughes). The applications were also chosen to provide a window on the controversy which is attached to the use of various optimization techniques. Three elements of the controversy will be discussed: the verifiability of the ideal or optimal models of the biomechanical system; the tractability of the optimization techniques; and the generality of the optimization techniques.”
© All rights reserved Fisher et al. and/or Human Factors Society
Mirka, Gary A. and Marras, William S. (1992): Modeling the Stochastic Nature of Trunk Muscle Forces. In: Proceedings of the Human Factors Society 36th Annual Meeting 1992. pp. 747-751.
“In an effort to understand the mechanism of low back disorders, researchers have developed EMG driven biomechanical models which estimate the magnitude of the internal reaction forces of the spine (compression and shear), by using information about the activity of the muscles of the trunk. But, because the trunk is multi-dimensional in nature, there is variability in the relative contribution of the various muscles, which implies variability in the reaction forces of the spine. Therefore, it may be more appropriate to discuss the range of spine reaction forces during a lift as opposed to the mean spine reaction force. The present research was an attempt to model the muscle forces stochastically and to develop a simulation model which predicts trunk muscle EMG that could occur during a lift. The simulated EMGs which resulted were then input into an EMG driven biomechanical model so the variability in spine reaction forces could be quantified. Under simple sagittally symmetric isometric conditions, compression which occurred at three standard deviations above the mean was 12% higher than that of the mean. The results for anterior shear (24% higher) and lateral shear (50% higher) showed even larger increases.”
© All rights reserved Mirka and Marras and/or Human Factors Society
Marras, William S., Lavender, Steven A., Leurgans, Sue E., Rajulu, Sudhakar L., Allread, W. Gary, Fathallah, Fadi A. and Ferguson, Sue A. (1992): Industrial Quantification of Occupationally-Related Low Back Disorder Risk Factors. In: Proceedings of the Human Factors Society 36th Annual Meeting 1992. pp. 757-760.
“Few assessment techniques have attempted to define the role of occupational trunk motion in the risk of occupationally-related low back disorder (LBD) even though laboratory studles have indicated that motion significantly increases spine loading. An in-vivo study was performed to assess the contribution of three-dimensional dynamic trunk motions to the risk of LBD during occupational lifting in industry. Over 400 industrial lifting jobs were studied in 48 industries. Specific manual materials handling jobs historically identify as either high risk or low risk for LBD were identified. A tri-axial electrogoniometer was worn by workers and documented the three-dimensional trunk motion characteristics associated with these high risk or low risk jobs. Workplace characteristics such as load moment arm, load weight, etc. were also documented for each of the repetitive lifting tasks. A multiple logistic regression model indicated that a combination of five trunk motion and workplace factors (lifting frequency, load moment, trunk lateral velocity, trunk twisting velocity, and trunk sagittal angle) predicted occupational-related LBD risk well. The analyses have enabled us to determine the LBD risk associated with combined changes in the magnitudes of the five factors. This model could be used as a quantitative, objective measure to redesign the workplace so that the risk of occupationally-related LBD is minimized.”
© All rights reserved Marras et al. and/or Human Factors Society
Sluchak, Thomas J., Hoffman, Mark S., Cochran, David J., Marras, William S., Grant, Katharyn and Habes, Daniel (1992): Ergonomics Research Efforts in the Supermarket Industry. In: Proceedings of the Human Factors Society 36th Annual Meeting 1992. pp. 779-782.
“This panel is composed of researchers from private industry, academia and NIOSH, who are currently involved with ergonomics research in the supermarket industry. Presenters summarize their research efforts and discuss key ergonomics challenges present in the supermarket industry today.”
© All rights reserved Sluchak et al. and/or Human Factors Society
Mirka, Gary A. and Marras, William S. (1991): Toward a More Accurate Description of the EMG/Force Relationship of the Erector Spinae Muscles. In: Proceedings of the Human Factors Society 35th Annual Meeting 1991. pp. 728-732.
Rajulu, Sudhakar L., Marras, William S. and Woolford, Barbara (1991): An Improved Simulation Based Biomechanical Model to Estimate Static Muscle Loadings. In: Proceedings of the Human Factors Society 35th Annual Meeting 1991. pp. 790-794.
Schoenmarklin, Richard W. and Marras, William S. (1991): Quantification for Wrist Motion and Cumulative Trauma Disorders in Industry. In: Proceedings of the Human Factors Society 35th Annual Meeting 1991. pp. 838-842.
Schoenmarklin, Richard W. and Marras, William S. (1990): A Dynamic Biomechanical Model of the Wrist Joint. In: D., Woods, and E., Roth, (eds.) Proceedings of the Human Factors Society 34th Annual Meeting 1990, Santa Monica, USA. pp. 805-809.
Mirka, Gary A., Sommerich, Carolyn M. and Marras, William S. (1989): Effects of Fatigue on Muscle Groups under Dynamic Exertions. In: Proceedings of the Human Factors Society 33rd Annual Meeting 1989. pp. 646-650.
“The present study was a quantitative investigation into the substitution patterns and other fatigue-related characteristics of the muscles of the upper leg during dynamic activity. Subjects performed fatigue-inducing leg extensions under varied force and velocity conditions. Electromyographic (EMG) data revealed subject dependent muscle substitution patterns that varied as a function of force/velocity combinations. The results also indicate an interaction between leg angle dependent variables and fatigue. Explanations for these effects are discussed.”
© All rights reserved Mirka et al. and/or Human Factors Society
Schoenmarklin, Richard W. and Marras, William S. (1989): Validation of a Hand/Wrist Electromechanical Goniometer. In: Proceedings of the Human Factors Society 33rd Annual Meeting 1989. pp. 718-722.
“This paper describes a new hand/wrist electromechanical goniometer that measures wrist angle, velocity, and acceleration in the radial/ulnar and flexion/extension planes. The research objectives of this paper were to validate the angle and motion measures from this goniometer. The results of this research show that the coefficient of variation of the angle measured by the goniometer and the angle measured by a video-based Motion Analysis system”
© All rights reserved Schoenmarklin and Marras and/or Human Factors Society
Lavender, Steven A., Sommerich, Carolyn M., Sudhakar, L. R. and Marras, William S. (1988): Trunk Muscle Loading in Non-Sagittally Symmetric Postures as a Result of Sudden Unexpected Loading Conditions. In: Proceedings of the Human Factors Society 32nd Annual Meeting 1988. pp. 665-669.
“The present study investigated the effect of warning time and magnitude of an external loading on the trunk muscular response to sudden loading conditions while in a non-sagittally symmetric posture. Eleven subjects were asked to catch falling weights of three magnitudes (3, 6, and 9 kg) with four levels of warning time (0, 100, 200, and 400 ms) in an asymmetric posture. For each of the eight muscles sampled with surface electrodes the integrated electromyographic (EMG) signal was interpreted in terms of its peak value, mean value, onset rate, and lead/lag time with reference to the weight drop. Results show monotonic relations between muscle force and levels of warning time, and muscle force and levels of weight. In addition, muscular forces in the left posterior trunk musculature ranged between two and five times greater than the right posterior trunk musculature in response to sudden loading conditions. This experiment demonstrates how sudden asymmetric loading, and specifically sudden loading without adequate warning time may be involved in the development of low back pain.”
© All rights reserved Lavender et al. and/or Human Factors Society
Lavender, Steven A. and Marras, William S. (1987): The Effects of Seam Height, Scaling Method, and Bar Weight Distribution on Scaling Effectiveness and Electromyographic Activity. In: Proceedings of the Human Factors Society 31st Annual Meeting 1987. pp. 471-475.
“Scaling bars are frequently used in underground mining for removing loose material from the roof and the walls. Previous research has demonstrated the scaling bar to be one of the hand tools more frequently involved in underground mining muscular-skeletal injuries. The present experiment investigated the role of seam height, scaling method and selected parameters of scaling bar design. Fourteen subjects worked in simulated mine environment and participated in all conditions of the experiment. Electromyographic (EMG) data was collected to study the relative involvement of six trunk muscles, and dynamometer output measured subjects' ability to use each bar and method effectively. Results suggest the parameters of weight and weight distribution to be important in scaling bar design. Also EMG data showed differences with tool parameters and the method used. Asymmetric loadings to the spine were found to be more extreme in the low roof conditions. These results suggest recommendations concerning tool design and proper training.”
© All rights reserved Lavender and Marras and/or Human Factors Society
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