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Larson DJ, Summers E, Brown SHM. Exploring how metronome pacing at varying movement speeds influences local dynamic stability and coordination variability of lumbar spine motion during repetitive lifting. Hum Mov Sci 2024; 93:103178. [PMID: 38217964 DOI: 10.1016/j.humov.2024.103178] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Revised: 12/20/2023] [Accepted: 01/06/2024] [Indexed: 01/15/2024]
Abstract
Auditory metronomes have been used to preserve movement consistency when examining local dynamic stability (LDS) and coordination variability (CV) of lumbar spine motion during repetitive movements. However, the potential influence of the metronome itself on these outcome measures has rarely been considered. Therefore, this study investigated the influence of different metronome paces (i.e., lifting speeds) on measures of lumbar spine LDS and thorax-pelvis CV during a repetitive lifting/lowering task in comparison to self-paced movements. Ten participants completed 5 repetitive lift/lower trials, where participants completed 35 consecutive repetitions (analysis on last 30 repetitions) at a self-selected pace for the first and last trial, and were paced by a 10 lift/min, 15 lift/min, and 20 lift/min metronome, in randomized order, for the remaining three trials. The average self-paced lift/lower speed before and after experiencing the three different metronome paced speeds was 16.2 (±1.02) and 17.2 (±0.73) lifts/min, respectively, and the most-preferred metronome pace trial was 15 lifts/min. Thorax-pelvis CV during the self-paced trials were similar (p > 0.05) to the 15 lift/min metronome paced trials, while greater thorax-pelvis CV was observed for the 10 lift/min compared to the 15 lift/min and 20 lift/min and second self-paced trial (all p < 0.026). This movement speed effect was not observed for lumbar spine LDS; however, more-dynamically stable movements were observed during all metronome paced trials in comparison to the self-paced trials. This study highlights that careful consideration is required when employing a metronome to control/manipulate movement characteristics while examining neuromuscular control using non-linear dynamical systems measures.
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Affiliation(s)
- Dennis J Larson
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada; Department of Kinesiology, University of Waterloo, Waterloo, ON, Canada
| | - Elspeth Summers
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada
| | - Stephen H M Brown
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada.
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2
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Marcotte JV, Robert-Lachaine X, Denis D, Muller A, Plamondon A, Corbeil P. Biomechanical differences in experts' and novices' footstep patterns during a palletizing task. APPLIED ERGONOMICS 2023; 106:103880. [PMID: 36063564 DOI: 10.1016/j.apergo.2022.103880] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Revised: 08/10/2022] [Accepted: 08/12/2022] [Indexed: 06/15/2023]
Abstract
Very few studies have examined differences between experts' and novices' foot positioning and movements during manual materials handling tasks. The impact of footstep patterns on low back loading needs to be better understood. The goals of this study were to characterize foot placement and movements in novices and experts and to assess their impact on back loading considering the height of grasp. The task consisted in transferring 24 15 kg boxes from a pallet to another. Foot placement and movements were classified with a recently developed taxonomy. Results show that experts' feet remained static more often than novices' feet during the lifting phase. Positioning the feet towards the deposit site during lifting increased asymmetrical moments, especially for novices. Positioning one foot forward increased asymmetrical moments for novices. Overall, footstep strategies are an effective indicator of low back exposure and should be considered in ergonomic studies.
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Affiliation(s)
- Jasmin Vallée Marcotte
- Department of Kinesiology, Université Laval, Québec, Québec, Canada; Centre Interdisciplinaire de Recherche en Réadaptation et Intégration Sociale (CIRRIS), Centre Intégré Universitaire de Santé et de Services Sociaux de La Capitale-Nationale (CIUSSS-CN), Québec, Canada.
| | - Xavier Robert-Lachaine
- Department of Kinesiology, Université Laval, Québec, Québec, Canada; Centre Interdisciplinaire de Recherche en Réadaptation et Intégration Sociale (CIRRIS), Centre Intégré Universitaire de Santé et de Services Sociaux de La Capitale-Nationale (CIUSSS-CN), Québec, Canada; Institut de Recherche Robert Sauvé en Santé et en Sécurité Du Travail (IRSST), 505 Boul. De Maisonneuve Ouest, Montréal, Québec, H3A 3C2, Canada
| | - Denys Denis
- Université Du Québec à Montréal (UQAM), Montréal, Québec, Canada
| | - Antoine Muller
- Univ Lyon, Université Claude Bernard Lyon 1, Univ Gustave Eiffel, LBMC UMR_T 9406, F-69622, Lyon, France
| | - André Plamondon
- Institut de Recherche Robert Sauvé en Santé et en Sécurité Du Travail (IRSST), 505 Boul. De Maisonneuve Ouest, Montréal, Québec, H3A 3C2, Canada
| | - Philippe Corbeil
- Department of Kinesiology, Université Laval, Québec, Québec, Canada; Centre Interdisciplinaire de Recherche en Réadaptation et Intégration Sociale (CIRRIS), Centre Intégré Universitaire de Santé et de Services Sociaux de La Capitale-Nationale (CIUSSS-CN), Québec, Canada.
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3
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Technical field measurements of muscular workload during stocking activities in supermarkets: cross-sectional study. Sci Rep 2022; 12:934. [PMID: 35042941 PMCID: PMC8766430 DOI: 10.1038/s41598-022-04879-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Accepted: 01/03/2022] [Indexed: 01/03/2023] Open
Abstract
Multiple studies have reported high prevalence of musculoskeletal disorders among supermarket workers. Technical field measurements can provide important knowledge about ergonomic risk factors for musculoskeletal disorders in the physical working environment, but these measurements are lacking in the supermarket sector. Therefore, using wearable electromyography and synchronous video recording in 75 supermarket workers, this cross-sectional study measured muscular workload during stocking activities in six different types of general store departments and during the thirteen most common work tasks across five different supermarket chains. Our results showed that muscular workload varies, especially for the low-back muscles, across (1) supermarket chains, (2) departments, and (3) specific stocking activities. Highest workloads of the low-back and neck/shoulders were seen in the fruit and vegetables department and during heavy, two-handed lifts of parcels (especially without using technical aids). In conclusion, physical work demands during supermarket stocking activities differ between chains, departments, and work tasks. These results can be used by company representatives and work environment professionals to specifically address and organize the stocking procedures to reduce the muscular workload during supermarket stocking.
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Madinei S, Kim S, Srinivasan D, Nussbaum MA. Effects of back-support exoskeleton use on trunk neuromuscular control during repetitive lifting: A dynamical systems analysis. J Biomech 2021; 123:110501. [PMID: 34000644 DOI: 10.1016/j.jbiomech.2021.110501] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Revised: 04/20/2021] [Accepted: 05/01/2021] [Indexed: 10/21/2022]
Abstract
Back-support exoskeletons (BSEs) are a promising ergonomic intervention to mitigate the risk of occupational low back pain. Although growing evidence points to the beneficial effects of BSEs, specifically in reducing low-back physical demands, there is limited understanding of potential unintended consequences of BSE use on neuromuscular control of the trunk during manual material handling (MMH). We quantified the effects of two passive BSEs (BackX™ AC and Laevo™ V2.5) on trunk dynamic stability and movement coordination during a repetitive lifting task. Eighteen participants (gender-balanced) completed four minutes of repetitive lifting in nine different conditions, involving symmetric and asymmetric postures when using the BSEs (along with no BSE as a control condition). Maximum Lyapunov exponents (short-term: λmax-s; long-term: λmax-l) and Floquet multipliers (FMmax) were respectively calculated to quantify the local dynamic and orbital stability of thorax and pelvis trajectories. Thorax-pelvis segmental coordination was also quantified using the continuous relative phase. Wearing the Laevo™ significantly increased λmax-s for the pelvis (by ~ 8%) and FMmax for the thorax and pelvis (by ~ 5-10%). Use of either BSE decreased the in-phase coordination pattern for the thorax-pelvis coupling (by ~ 15%). These results suggest that BSE use can compromise neuromuscular control of the trunk, and caution should thus be used in selecting a suitable BSE for use in a given MMH task. Future work is needed, however, to assess the generalizability of different BSE design approaches in terms of unintended short-term and long-term effects on trunk neuromuscular control.
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Affiliation(s)
- Saman Madinei
- Department of Industrial and Systems Engineering, Virginia Tech, Blacksburg, VA 24061, USA
| | - Sunwook Kim
- Department of Industrial and Systems Engineering, Virginia Tech, Blacksburg, VA 24061, USA
| | - Divya Srinivasan
- Department of Industrial and Systems Engineering, Virginia Tech, Blacksburg, VA 24061, USA
| | - Maury A Nussbaum
- Department of Industrial and Systems Engineering, Virginia Tech, Blacksburg, VA 24061, USA.
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Larson DJ, Wang Y, Zwambag DP, Brown SHM. Characterizing Local Dynamic Stability of Lumbar Spine Sub-regions During Repetitive Trunk Flexion-Extension Movements. Front Sports Act Living 2019; 1:48. [PMID: 33344971 PMCID: PMC7739619 DOI: 10.3389/fspor.2019.00048] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Accepted: 09/25/2019] [Indexed: 11/13/2022] Open
Abstract
Using a technique of tracking intersegmental spine kinematics via skin surface markers, this study aimed to estimate local dynamic spine stability across smaller sub-regions (or segments) of the lumbar spine while also considering the impact of an external pelvic constraint during repetitive movements. Sixteen participants (10 males) performed two trials [Free Motion (FM), Pelvis Constrained (PC)] each consisting of 65 repetitive trunk flexion-extension movements to assess dynamic spine stability using maximum Lyapunov exponents (LyE). First, results indicated that LyE obtained from analysis of 30 repetitive flexion-extension movements did not differ from those obtained from analysis of greater numbers of repetitive movements, which aligns with results from a previous study for the whole lumbar spine. Next, for both males and females, and FM and PC trials, the most caudal region of the lumbar spine behaved the most dynamically stable, while upper lumbar regions behaved the most dynamically unstable. Finally, females demonstrated greater lumbar and intersegmental stability (lower LyE) during PC trials compared to FM, while males demonstrated slightly decreased lumbar and intersegmental stability (higher LyE) during PC trials compared to FM; this resulted in PC trials, but not FM trials, being different between sexes. Altogether, these data show that dynamic stability of lumbar spine sub-regions may be related to the proximity of the motion segment to rigid skeletal structures, and that consideration is needed when deciding whether to constrain the pelvis during analyses of dynamic spine stability.
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Affiliation(s)
- Dennis J Larson
- Spine and Muscle Biomechanics Lab, Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada
| | - Yunxi Wang
- Spine and Muscle Biomechanics Lab, Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada
| | - Derek P Zwambag
- Department of Kinesiology and Physical Education, Wilfrid Laurier University, Waterloo, ON, Canada
| | - Stephen H M Brown
- Spine and Muscle Biomechanics Lab, Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada
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Badawy M, Schall MC, Zabala ME, Coker J, Sesek RF, Gallagher S, Davis GA. Effects of age and obesity on trunk kinetics and kinematics during dominant side one-handed carrying. J Biomech 2019; 94:107-114. [PMID: 31376977 DOI: 10.1016/j.jbiomech.2019.07.016] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2019] [Revised: 06/21/2019] [Accepted: 07/15/2019] [Indexed: 11/19/2022]
Abstract
The proportions of older and obese people are increasing in both the general and working populations worldwide. Older and obese individuals are more susceptible to work-related musculoskeletal disorders (MSDs) in comparison with healthy, younger individuals. Manual material handling (MMH) is associated with the development of work-related MSDs. Although previous research has suggested that one-handed carrying is a particularly undesirable method of MMH, the effects of one-handed carrying on trunk kinetics and kinematics among older and/or obese people have not been adequately studied. The objective of this study was to examine the effects of age and obesity on trunk angles and moments during dominant side one-handed carrying of various load magnitudes. Twenty (20) participants divided into four groups with respect to age (young and older) and obesity (obese and non-obese) carried different loads (No-load [0 kg], Light [5.67 kg], and Heavy [10.21 kg]) in their dominant hand for approximately 6 m. Three-dimensional (3D) trunk angles and moments approximately about the L4/L5 vertebral segment were calculated using Visual3D. The findings indicated that while carrying a load in the dominant hand plays an important role in changing trunk kinematics and kinetics, the results were not dependent on age and/or obesity category. Absolute moments were greatest among participants in the obese groups; however, these moments were mitigated when normalized to body weight and height (%BW * Ht). Age did not exacerbate the effects of load magnitude on trunk kinetics and kinematics.
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Affiliation(s)
- Mohamed Badawy
- Department of Industrial and Systems Engineering, Auburn University, Auburn, AL, USA
| | - Mark C Schall
- Department of Industrial and Systems Engineering, Auburn University, Auburn, AL, USA
| | - Michael E Zabala
- Department of Mechanical Engineering, Auburn University, Auburn, AL, USA
| | - Jordan Coker
- Department of Mechanical Engineering, Auburn University, Auburn, AL, USA
| | - Richard F Sesek
- Department of Industrial and Systems Engineering, Auburn University, Auburn, AL, USA
| | - Sean Gallagher
- Department of Industrial and Systems Engineering, Auburn University, Auburn, AL, USA
| | - Gerard A Davis
- Department of Industrial and Systems Engineering, Auburn University, Auburn, AL, USA
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Exploration of different classes of metrics to characterize motor variability during repetitive symmetric and asymmetric lifting tasks. Sci Rep 2019; 9:9821. [PMID: 31285469 PMCID: PMC6614496 DOI: 10.1038/s41598-019-46297-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Accepted: 06/25/2019] [Indexed: 11/16/2022] Open
Abstract
The substantial kinematic degrees-of-freedom available in human movement lead to inherent variations in a repetitive movement, or motor variability (MV). Growing evidence suggests that characterizing MV permits a better understanding of potential injury mechanisms. Several diverse methods, though, have been used to quantify MV, but limited evidence exists regarding the merits of these methods in the occupational context. In this work, we explored different classes of methods for characterizing MV during symmetric and asymmetric box lifting tasks. Kinematic MV of both the whole-body center-of-mass (COM) and the box were quantified, using metrics derived from a linear method (Standard Deviation), a non-linear method (Sample Entropy; an index of movement regularity), and a novel application of an equifinality method (Goal Equivalent Manifold; an index related to the set of effective motor solutions). Our results suggest that individuals manipulate regularity and the set of effective motor solutions to overcome unwanted motor noises related to the COM. These results, together with earlier evidence, imply that individuals may prioritize stability over variability with increasing task difficulty. Task performance also appeared to deteriorate with decreasing variability and regularity of the COM. We conclude that diverse metrics of MV may be complimentary to reveal differences in MV.
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Sedighi A, Nussbaum MA. Temporal changes in motor variability during prolonged lifting/lowering and the influence of work experience. J Electromyogr Kinesiol 2017; 37:61-67. [DOI: 10.1016/j.jelekin.2017.09.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Revised: 08/09/2017] [Accepted: 09/08/2017] [Indexed: 10/18/2022] Open
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LIN CJ, CHENG CF. Lifting speed preferences and their effects on the maximal lifting capacity. INDUSTRIAL HEALTH 2017; 55:27-34. [PMID: 27383532 PMCID: PMC5285311 DOI: 10.2486/indhealth.2016-0032] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/19/2016] [Accepted: 06/29/2016] [Indexed: 06/06/2023]
Abstract
The objectives of this study were to evaluate how lifting capacity and subjective preferences are affected by different lifting speeds. The maximum lifting capacity of lift was determined with three independent variables, lifting speed, lifting technique, and lifting height. Questionnaires were evaluated after the experiment by the participants for the lifting speed preferences. This study found that the lifting speed was a significant factor in the lifting capacity (p<0.001); and the lifting height (p<0.001) and the interaction of lifting speed and lifting height (p=0.005) affected the lifting capacity significantly. The maximal lifting capacity was achieved around the optimal speed that was neither too fast nor too slow. Moreover, the participants' preferred lifting speeds were consistently close to the optimal lifting speed. The results showed that the common lifting practice guideline to lift slowly might make the worker unable to generate a large lifting capacity.
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Affiliation(s)
- Chiuhsiang Joe LIN
- Department of Industrial Management, National Taiwan University of Science and Technology, Taiwan
| | - Chih-Feng CHENG
- Department of Industrial Management, National Taiwan University of Science and Technology, Taiwan
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Gagnon D, Plamondon A, Larivière C. A biomechanical comparison between expert and novice manual materials handlers using a multi-joint EMG-assisted optimization musculoskeletal model of the lumbar spine. J Biomech 2016; 49:2938-2945. [PMID: 27469898 DOI: 10.1016/j.jbiomech.2016.07.009] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Revised: 07/05/2016] [Accepted: 07/08/2016] [Indexed: 10/21/2022]
Abstract
Expertise is a key factor modulating the risk of low back disorders (LBD). Through years of practice in the workplace, the typical expert acquires high level specific skills and maintains a clean record of work-related injuries. Ergonomic observations of manual materials handling (MMH) tasks show that expert techniques differ from those of novices, leading to the idea that expert techniques are safer. Biomechanical studies of MMH tasks performed by experts/novices report mixed results for kinematic/kinetic variables, evoking potential internal effect of expertise. In the context of series of box transfers simulated by actual workers, detailed internal loads predicted by a multiple-joint EMG-assisted optimization lumbar spine model are compared between experts and novices. The results confirmed that the distribution of internal moments are modulated by worker expertise. Experts flexed less their lumbar spine and exerted more active muscle forces while novices relied more on passive resistance of the muscles and ligamentous spine. More specifically for novices, the passive contributions came from global extensor muscles, selected local extensor muscles, and passive structures of the lumbar spine (ligaments and discs). The distinctive distribution of internal forces was not concomitant with a similar effect on joint forces, these forces being dependent on external loading which was equivalent between experts and novices. From a safety standpoint, the present results suggest that experts were more efficient than novices in partitioning internal moment contributions to balance net (external) loading. Thus, safer handling practices might be seen as a result of experts׳ experience.
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Affiliation(s)
- Denis Gagnon
- Faculté des sciences de l׳activité physique, Université de Sherbrooke, Sherbrooke, Québec, Canada.
| | - André Plamondon
- Institut de recherche Robert Sauvé en santé et en sécurité du travail, Montréal, Québec, Canada
| | - Christian Larivière
- Institut de recherche Robert Sauvé en santé et en sécurité du travail, Montréal, Québec, Canada
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Asgari M, Sanjari MA, Mokhtarinia HR, Moeini Sedeh S, Khalaf K, Parnianpour M. The effects of movement speed on kinematic variability and dynamic stability of the trunk in healthy individuals and low back pain patients. Clin Biomech (Bristol, Avon) 2015; 30:682-8. [PMID: 26021879 DOI: 10.1016/j.clinbiomech.2015.05.005] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/06/2014] [Revised: 05/03/2015] [Accepted: 05/07/2015] [Indexed: 02/07/2023]
Abstract
BACKGROUND Comparison of the kinematic variability and dynamic stability of the trunk between healthy and low back pain patient groups can contribute to gaining valuable information about the movement patterns and neuromotor strategies involved in various movement tasks. METHODS Fourteen chronic low back pain patients with mild symptoms and twelve healthy male volunteers performed repeated trunk flexion-extension movements in the sagittal plane at three different speeds: 20 cycles/min, self-selected, and 40 cycles/min. Mean standard deviations, coefficient of variation and variance ratio as variability measures; maximum finite-time Lyapunov exponents and maximum Floquet multipliers as stability measures were computed from trunk kinematics. FINDINGS Higher speed significantly reduced the kinematic variability, while it increased short-term Lyapunov exponents. Long-term Lyapunov exponents were higher at self-selected speed and lower in low back pain patients as compared to control volunteers. Floquet multipliers were larger at self-selected speed and during higher pace trunk movements. INTERPRETATION Our findings suggest that slower pace flexion-extension trunk movements are associated with more motor variation as well as local and orbital stability, implying less potential risk of injury for the trunk. Individuals with and without low back pain consistently recruited a closed-loop control strategy towards achieving trunk stability. Chronic low back pain patients exhibited more stable trunk movements over long-term periods, indicating probable temporary pain relief functional adaption strategies. These results may be used towards the development of more effective personalized rehabilitation strategies and quantitative spinal analysis tools for low back pain detection, diagnosis and treatment, as well as improvement of workspace and occupational settings.
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Affiliation(s)
- Morteza Asgari
- Department of Mechanical Engineering, Sharif University of Technology, Tehran, Iran.
| | - Mohammad Ali Sanjari
- Biomechanics Lab, Rehabilitation Research Center, Faculty of Rehabilitation, Department of Rehabilitation Basic Sciences, Iran University of Medical Sciences, Tehran, Iran.
| | - Hamid Reza Mokhtarinia
- Department of Ergonomics, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran.
| | - Samaneh Moeini Sedeh
- Department of Mechanical Engineering, Sharif University of Technology, Tehran, Iran.
| | - Kinda Khalaf
- Department of Biomedical Engineering, Khalifa University of Science Technology and Research, Abu Dhabi, United Arab Emirates.
| | - Mohamad Parnianpour
- Department of Mechanical Engineering, Sharif University of Technology, Tehran, Iran.
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Muslim K, Nussbaum MA. Traditional posterior load carriage: effects of load mass and size on torso kinematics, kinetics, muscle activity and movement stability. ERGONOMICS 2015; 59:99-111. [PMID: 25994335 DOI: 10.1080/00140139.2015.1053538] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2014] [Accepted: 05/14/2015] [Indexed: 06/04/2023]
Abstract
UNLABELLED Traditional posterior load carriage (PLC), done without the use of an assistive device (e.g., backpack), has been associated with low back pain (LBP) development. This study evaluated the effects of important task demands, related to load mass and size, on potential mechanisms linking traditional PLC with LBP. Nine healthy participants completed PLC tasks with three load masses (20%, 35% and 50% of individual body mass) and three load sizes (small, medium and large). Torso kinematics, kinetics, muscle activity and slip risk were evaluated during PLC on a walkway, and torso movement stability was quantified during PLC on a treadmill. Increasing load mass caused increased torso flexion, L5/S1 flexion moment, abdominal muscle activity and torso movement stability in the frontal plane. Increasing load size also caused higher torso flexion, peak torso angular velocity and acceleration, and abdominal muscle activity. Complex interactive effects of load mass and size were found on paraspinal muscle activity and slip risk. Specific task demands, related to load mass and size, may thus influence the risk of LBP during PLC. PRACTITIONER SUMMARY This study examined the effects of load mass and size on low back pain (LBP) risk using intermediary measures derived from torso kinematics, kinetics and muscle activity. Our current findings, along with earlier work, suggest that load mass and size can influence LBP risk, and that use of smaller and light loads may be beneficial during PLC.
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Affiliation(s)
- Khoirul Muslim
- a Industrial Engineering , Institute of Technology Bandung , Bandung , Indonesia
| | - Maury A Nussbaum
- b Department of Industrial and Systems Engineering , Virginia Tech , Blacksburg , USA
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Riley AE, Craig TD, Sharma NK, Billinger SA, Wilson SE. Novice lifters exhibit a more kyphotic lifting posture than experienced lifters in straight-leg lifting. J Biomech 2015; 48:1693-9. [PMID: 26077846 DOI: 10.1016/j.jbiomech.2015.05.022] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Revised: 05/20/2015] [Accepted: 05/24/2015] [Indexed: 10/23/2022]
Abstract
As torso flexion and repetitive lifting are known risk factors for low back pain and injury, it is important to investigate lifting techniques that might reduce injury during repetitive lifting. By normalizing lumbar posture to a subject's range of motion (ROM), as a function of torso flexion, this research examined when subjects approached their range of motion limits during dynamic lifting tasks. For this study, it was hypothesized that experienced lifters would maintain a more neutral lumbar angle relative to their range of motion, while novice lifters would approach the limits of their lumbar ROM during the extension phase of a straight-leg lift. The results show a statistically significant difference in lifting patterns for these two groups supporting this hypothesis. The novice group maintained a much more kyphotic lumbar angle for both the flexion (74% of the lumbar angle ROM) and extension phases (86% of the lumbar angle ROM) of the lifting cycle, while the experienced group retained a more neutral curvature throughout the entire lifting cycle (37% of lumbar angle ROM in flexion and 48% of lumbar angle ROM in extension). By approaching the limits of their range of motion, the novice lifters could be at greater risk of injury by placing greater loads on the supporting soft tissues of the spine. Future research should examine whether training subjects to assume more neutral postures during lifting could indeed lower injury risks.
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Affiliation(s)
- A E Riley
- Department of Mechanical Engineering, University of Kansas, Lawrence, KS, United States
| | - T D Craig
- Department of Mechanical Engineering, University of Kansas, Lawrence, KS, United States
| | - N K Sharma
- Department of Physical Therapy and Rehabilitation Sciences, University of Kansas Medical Center, Kansas City, KS, United States
| | - S A Billinger
- Department of Physical Therapy and Rehabilitation Sciences, University of Kansas Medical Center, Kansas City, KS, United States
| | - S E Wilson
- Department of Mechanical Engineering, University of Kansas, Lawrence, KS, United States.
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14
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Lee J, Nussbaum MA, Kyung G. Effects of work experience on fatigue-induced biomechanical changes during repetitive asymmetric lifts/lowers. ERGONOMICS 2014; 57:1875-1885. [PMID: 25216272 DOI: 10.1080/00140139.2014.957733] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Repetitive lifting/lowering is associated with an increased risk of work-related low back disorders (WRLBDs), and fatigue may exacerbate such risk. Work methods used by experienced workers are potential models for developing worker training to reduce WRLBDs, though whether experience modifies the effects of fatigue on WRLBD risk is largely unknown. Here, six novices and six experienced workers completed 185 cycles of repetitive, asymmetric lifts/lowers. Physical demands, whole-body balance and torso movement stability were assessed using torso kinematics/kinetics, linear/angular momenta and Lyapunov exponents, respectively. Several fatigue-induced changes in movement strategies were evident. Novices decreased and experienced workers increased peak lumbar moments post-fatigue, suggesting lower WRLBD risks among the former in terms of torso kinetics. Other than lumbar moments, though, fatigue substantially reduced group-level differences in torso twisting velocities and accelerations. Post-fatigue movement strategies of experienced workers thus did not appear to be advantageous in terms of WRLBD risk.
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Affiliation(s)
- Jungyong Lee
- a Ergonomics Team, Hyundai Motor Company , Gyeonggi-Do , Republic of Korea
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15
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Fischer SL, Johnson R, Abdoli-Eramaki M, Woodcock K. Investigating the Effect of Experience and Duration on Kinematics During 1 Hour of Sign Language Interpreting. ACTA ACUST UNITED AC 2014. [DOI: 10.1080/21577323.2014.948694] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Affiliation(s)
- Steven L. Fischer
- School of Kinesiology and Health Studies, Queen's University, SKHS Building, 28 Division Street, Kingston, Ontario, Canada K7L 3N6
| | - Ron Johnson
- Queen's University, Kingston, Ontario, Canada
| | | | - Kathryn Woodcock
- School of Occupational and Public Health, Ryerson University, Toronto, Ontario, Canada
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Plamondon A, Delisle A, Bellefeuille S, Denis D, Gagnon D, Larivière C. Lifting strategies of expert and novice workers during a repetitive palletizing task. APPLIED ERGONOMICS 2014; 45:471-481. [PMID: 23891462 DOI: 10.1016/j.apergo.2013.06.008] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2012] [Revised: 05/27/2013] [Accepted: 06/21/2013] [Indexed: 06/02/2023]
Abstract
Thirty manual material handlers (15 experts and 15 novices) were invited to perform series of box transfers under conditions similar to those of large distribution centers. The objective of the present study was to verify whether multiple box transfers leading to fatigue would also lead to differences between expert and novice workers in joint motions and in back loading variables (L5/S1 moments). The task consisted in transferring 24 15-kg boxes from one pallet to another (4 layers of boxes; 6 boxes/layer: 3 in the front row, 3 in the back) at a self-determined pace and then at an imposed pace of 9 lifts/min for a total of 240 lifts. The underlying idea was to set a challenging task that would force the experts to use their skills. Full-body 3D kinematic data were collected as well as external foot forces. A dynamic 3D linked segment model was used to estimate the net moments at L5/S1. The results clearly show that the experts bent their lumbar spine less (10° less) and were closer (4 cm) to the box than novice workers. Knee flexions were similar in both groups except when the box was lifted from ground level (expert ≈ 71°, novice ≈ 48°). The peak resultant moment was not statistically different (expert = 168 Nm, novice = 184 Nm) although experts had lower values on average than novices when lifting heights (and deposit heights) of the boxes increased. Therefore, experts differed from novice workers mostly in the posture-related variables. These differences are especially important to consider when the box is located on the ground, as the back posture and back loading are then at their greatest magnitude and could have a major impact on the distribution of internal forces on the spine.
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Affiliation(s)
- A Plamondon
- Institut de recherche Robert Sauvé en santé et en sécurité du travail (IRSST), 505 Boul. De Maisonneuve Ouest, Montréal, Québec, Canada H3A 3C2.
| | - A Delisle
- Faculté d'éducation physique et sportive, Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - S Bellefeuille
- Institut de recherche Robert Sauvé en santé et en sécurité du travail (IRSST), 505 Boul. De Maisonneuve Ouest, Montréal, Québec, Canada H3A 3C2
| | - D Denis
- Institut de recherche Robert Sauvé en santé et en sécurité du travail (IRSST), 505 Boul. De Maisonneuve Ouest, Montréal, Québec, Canada H3A 3C2
| | - D Gagnon
- Faculté d'éducation physique et sportive, Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - C Larivière
- Institut de recherche Robert Sauvé en santé et en sécurité du travail (IRSST), 505 Boul. De Maisonneuve Ouest, Montréal, Québec, Canada H3A 3C2
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