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Phoenix EM, McDonnell JM, Butler JS, Fuller C, Morrison CM, Dolan RT. 'Barbie Tox' - A cosmetic trend with potential functional implications. Surgeon 2024; 22:e157-e158. [PMID: 38637190 DOI: 10.1016/j.surge.2024.04.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2023] [Accepted: 04/01/2024] [Indexed: 04/20/2024]
Affiliation(s)
- Eimear M Phoenix
- Department of Plastic and Reconstructive Surgery, St Vincent's University Hospital, Dublin, Ireland; Department of Surgery, Royal College of Surgeons Ireland, St Stephen's Green, Dublin, Ireland.
| | - Jake M McDonnell
- National Spinal Injuries Unit, Mater Misericordiae University Hospital, Dublin 7, Ireland
| | - Joseph S Butler
- National Spinal Injuries Unit, Mater Misericordiae University Hospital, Dublin 7, Ireland
| | - Colm Fuller
- Department of Physiotherapy, Santry Sports Clinic, Dublin, Ireland
| | - Colin M Morrison
- Department of Plastic and Reconstructive Surgery, St Vincent's University Hospital, Dublin, Ireland
| | - Roisin T Dolan
- Department of Surgery, Royal College of Surgeons Ireland, St Stephen's Green, Dublin, Ireland; Department of Plastic and Reconstructive Surgery, Beaumont Hospital, Dublin, Ireland
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Kazemi Z, Arjmand N, Mazloumi A, Karimi Z, Keihani A, Ghasemi MS. Effect of muscular fatigue on the cumulative lumbar damage during repetitive lifting task: a comparative study of damage calculation methods. ERGONOMICS 2024; 67:566-581. [PMID: 37418312 DOI: 10.1080/00140139.2023.2234678] [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: 04/14/2023] [Accepted: 07/02/2023] [Indexed: 07/09/2023]
Abstract
Several methods have been put forward to quantify cumulative loads; however, limited evidence exists as to the subsequent damages and the role of muscular fatigue. The present study assessed whether muscular fatigue could affect cumulative damage imposed on the L5-S1 joint. Trunk muscle electromyographic (EMG) activities and kinematics/kinetics of 18 healthy male individuals were evaluated during a simulated repetitive lifting task. A traditional EMG-assisted model of the lumbar spine was modified to account for the effect of erector spinae fatigue. L5-S1 compressive loads for each lifting cycle were estimated based on varying (i.e. actual), fatigue-modified, and constant Gain factors. The corresponding damages were integrated to calculate the cumulative damage. Moreover, the damage calculated for one lifting cycle was multiplied by the lifting frequency, as the traditional approach. Compressive loads and the damages obtained through the fatigue-modified model were predicted in close agreement with the actual values. Similarly, the difference between actual damages and those driven by the traditional approach was not statistically significant (p = 0.219). However, damages based on a constant Gain factor were significantly greater than those based on the actual (p = 0.012), fatigue-modified (p = 0.017), and traditional (p = 0.007) approaches.Practitioner summary: In this study, we managed to include the effect of muscular fatigue on cumulative lumbar damage calculations. Including the effect of muscular fatigue leads to an accurate estimation of cumulative damages while eliminating computational complexity. However, using the traditional approach also appears to provide acceptable estimates for ergonomic assessments.
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Affiliation(s)
- Zeinab Kazemi
- Department of Industrial Engineering, Clemson University, Clemson, SC, USA
| | - Navid Arjmand
- Department of Mechanical Engineering, Sharif University of Technology, Tehran, Iran
| | - Adel Mazloumi
- Department of Occupational Health Engineering, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran
- Sports Medicine Research Center, Neuroscience Institute, Tehran University of Medical Sciences, Tehran, Iran
| | - Zanyar Karimi
- Department of Ergonomics, School of Public Health, Urmia University of Medical Sciences, Tehran, Iran
| | - Ahmadreza Keihani
- Department of Medical Physics and Biomedical Engineering, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
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3
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Davidson JB, Cashaback JGA, Fischer SL. Exploring Optimal Objective Function Weightings to Predict Lifting Postures Under Unfatigued and Fatigued States. HUMAN FACTORS 2024; 66:510-527. [PMID: 35653836 PMCID: PMC10757399 DOI: 10.1177/00187208221096928] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Accepted: 03/24/2022] [Indexed: 06/15/2023]
Abstract
OBJECTIVE To explore whether the optimal objective function weightings change when using a digital human model (DHM) to predict origin and destination lifting postures under unfatigued and fatigued states. BACKGROUND The ability to predict human postures can depend on state-based influences (e.g., fatigue). Altering objective function weightings within a predictive DHM could improve the ability to predict tasks specific lifting postures under unique fatigue states. METHOD A multi-objective optimization-based DHM was used to predict origin and destination lifting postures for ten anthropometrically scaled avatars by using different objective functions weighting combinations. Predicted and measured postures were compared to determine the root mean squared error. A response surface methodology was used to identify the optimal objective function weightings, which was found by generating the posture that minimized error between measured and predicted lifting postures. The resultant weightings were compared to determine if the optimal objective function weightings changed for different lifting postures or fatigue states. RESULTS Discomfort and total joint torque weightings were affected by posture (origin/destination) and fatigue state (unfatigued/fatigued); however, post-hoc differences between fatigue states and lifting postures were not sufficiently large to be detected. Weighting the discomfort objective function alone tended to predict postures that generalized well to both postures and fatigue states. CONCLUSION Lift postures were optimal predicted using the minimization of discomfort objective function regardless of fatigue state. APPLICATION Weighting the discomfort objective can predict unfatigued postures, but more research is needed to understand the optimal objective function weightings to predict postures during a fatigued state.
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4
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Tabasi A, Brouwer NP, Kingma I, van Dijk W, de Looze MP, Moya-Esteban A, Kooij HVD, van Dieën JH. The effect of back muscle fatigue on EMG and kinematics based estimation of low-back loads and active moments during manual lifting tasks. J Electromyogr Kinesiol 2023; 73:102815. [PMID: 37688848 DOI: 10.1016/j.jelekin.2023.102815] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Revised: 07/10/2023] [Accepted: 08/30/2023] [Indexed: 09/11/2023] Open
Abstract
This study investigated the effects of back muscle fatigue on the estimation of low-back loads and active low-back moments during lifting, using an EMG and kinematics based model calibrated with data from an unfatigued state. Fourteen participants performed lifting tasks in unfatigued and fatigued states. Fatigue was induced through semi-static forward bending. EMG, kinematics, and ground reaction forces were measured, and low-back loads were estimated using inverse dynamics and EMG-driven muscle model. A regression model was developed using data from a set of calibration lifts, and its accuracy was evaluated for unfatigued and fatigued lifts. During the fatigue-inducing task, the EMG amplitude increased by 2.8 %MVC, representing a 38% increase relative to the initial value. However, during the fatigued lifts, the peak EMG amplitude was found to be 1.6 %MVC higher than that observed during the unfatigued lifts, representing a mere 4% increase relative to the baseline unfatigued peak EMG amplitude. Kinematics and low-back load estimates remained unaffected. Regression model estimation errors remained unaffected for 5 kg lifts, but increased by no more than 5% of the peak active low-back moment for 15 kg lifts. We conclude that the regression-based estimation quality of active low-back moments can be maintained during periods of muscle fatigue, although errors may slightly increase for heavier loads.
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Affiliation(s)
- A Tabasi
- Dept. of Human Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam, the Netherlands; TNO, Leiden, the Netherlands.
| | - N P Brouwer
- Dept. of Human Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam, the Netherlands
| | - I Kingma
- Dept. of Human Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam, the Netherlands
| | | | | | - A Moya-Esteban
- Department of Biomechanical Engineering, University of Twente, Enschede, the Netherlands
| | - H V D Kooij
- Department of Biomechanical Engineering, University of Twente, Enschede, the Netherlands
| | - J H van Dieën
- Dept. of Human Movement Sciences, Vrije Universiteit Amsterdam, Amsterdam, the Netherlands
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5
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Tissot LPM, Evans DW, Kirby E, Liew BXW. Tampa Scale of Kinesiophobia may underestimate task-specific fear of movement in people with and without low back pain. Pain Rep 2023; 8:e1081. [PMID: 37293339 PMCID: PMC10247215 DOI: 10.1097/pr9.0000000000001081] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2023] [Revised: 04/11/2023] [Accepted: 04/21/2023] [Indexed: 06/10/2023] Open
Abstract
Introduction The Tampa Scale of Kinesiophobia (TSK) is commonly used to assess fear of movement (FoM) in people with low back pain (LBP). However, the TSK does not provide a task-specific measure of FoM, whereas image-based or video-based methods may do so. Objectives To compare the magnitude of FoM when assessed using 3 methods (TSK-11, image of lifting, video of lifting) in 3 groups of people: current LBP (LBP), recovered LBP (rLBP), and asymptomatic controls (control). Methods Fifty-one participants completed the TSK-11 and rated their FoM when viewing images and videos depicting people lifting objects. Low back pain and rLBP participants also completed the Oswestry Disability Index (ODI). Linear mixed models were used to estimate the effects of methods (TSK-11, image, video) and group (control, LBP, rLBP). Linear regression models were used to assess associations between the methods on ODI after adjusting for group. Finally, a linear mixed model was used to understand the effects of method (image, video) and load (light, heavy) on fear. Results In all groups, viewing images (P = 0.009) and videos (P = 0.038) elicited greater FoM than that captured by the TSK-11. Only the TSK-11 was significantly associated with the ODI (P < 0.001). Finally, there was a significant main effect of load on fear (P < 0.001). Conclusion Fear of specific movements (eg, lifting) may be better measured using task-specific measures, such as images and videos, than by task-generic questionnaires, such as the TSK-11. Being more strongly associated with the ODI, the TSK-11 still plays an important role in understanding the impact of FoM on disability.
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Affiliation(s)
- Liam-Pierre Mathieu Tissot
- School of Sport, Rehabilitation and Exercise Sciences, University of Essex, Colchester, Essex, United Kingdom
| | - David William Evans
- Centre of Precision Rehabilitation for Spinal Pain, School of Sport, Exercise and Rehabilitation Sciences, University of Birmingham, Edgbaston, Birmingham, United Kingdom
| | - Edward Kirby
- Musculoskeletal Physiotherapy, Essex Partnership University NHS Foundation Trust, Runwell, Wickford, United Kingdom
| | - Bernard Xian Wei Liew
- School of Sport, Rehabilitation and Exercise Sciences, University of Essex, Colchester, Essex, United Kingdom
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Saraceni N, Campbell A, Kent P, Ng L, Straker L, O'Sullivan P. Does intra-lumbar flexion during lifting differ in manual workers with and without a history of low back pain? A cross-sectional laboratory study. ERGONOMICS 2022; 65:1380-1396. [PMID: 35098885 DOI: 10.1080/00140139.2022.2036819] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Accepted: 01/13/2022] [Indexed: 06/14/2023]
Abstract
Advice to limit or avoid a flexed lumbar curvature during lifting is widely promoted to reduce the risk of low back pain (LBP), yet there is very limited evidence to support this relationship. To provide higher quality evidence this study compared intra-lumbar flexion in manual workers with (n = 21) and without a history of LBP (n = 21) during a repeated lifting task. In contrast to common expectations, the LBP group demonstrated less peak absolute intra-lumbar flexion during lifting than the noLBP group [adjusted difference -3.7° (95%CI -6.9 to -0.6)]. The LBP group was also further from the end of range intra-lumbar flexion and did not use more intra-lumbar range of motion during any lift condition (both symmetrical and asymmetrical lifts and different box loads). Peak absolute intra-lumbar flexion was more variable in the LBP group during lifting and both groups increased their peak absolute intra-lumbar flexion over the lift repetitions. This high-quality capture of intra-lumbar spine flexion during repeated lifting in a clinically relevant cohort questions dominant safe lifting advice.Practitioner summary: Lifting remains a common trigger for low back pain (LBP). This study demonstrated that people with LBP, lift with less intra-lumbar flexion than those without LBP. Providing the best quality in-vivo laboratory evidence, that greater intra-lumbar flexion is not associated with LBP in manual workers, raising questions about lifting advice.
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Affiliation(s)
- Nic Saraceni
- Curtin School of Allied Health, Curtin University, Perth, Australia
| | - Amity Campbell
- Curtin School of Allied Health, Curtin University, Perth, Australia
| | - Peter Kent
- Curtin School of Allied Health, Curtin University, Perth, Australia
- Department of Sports Science and Clinical Biomechanics, University of Southern Denmark, Odense, Denmark
| | - Leo Ng
- Curtin School of Allied Health, Curtin University, Perth, Australia
| | - Leon Straker
- Curtin School of Allied Health, Curtin University, Perth, Australia
| | - Peter O'Sullivan
- Curtin School of Allied Health, Curtin University, Perth, Australia
- Body Logic Physiotherapy Clinic, Perth, Australia
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Kazemi Z, Mazloumi A, Arjmand N, Keihani A, Karimi Z, Ghasemi MS, Kordi R. A Comprehensive Evaluation of Spine Kinematics, Kinetics, and Trunk Muscle Activities During Fatigue-Induced Repetitive Lifting. HUMAN FACTORS 2022; 64:997-1012. [PMID: 33497290 DOI: 10.1177/0018720820983621] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
OBJECTIVE Spine kinematics, kinetics, and trunk muscle activities were evaluated during different stages of a fatigue-induced symmetric lifting task over time. BACKGROUND Due to neuromuscular adaptations, postural behaviors of workers during lifting tasks are affected by fatigue. Comprehensive aspects of these adaptations remain to be investigated. METHOD Eighteen volunteers repeatedly lifted a box until perceived exhaustion. Body center of mass (CoM), trunk and box kinematics, and feet center of pressure (CoP) were estimated by a motion capture system and force-plate. Electromyographic (EMG) signals of trunk/abdominal muscles were assessed using linear and nonlinear approaches. The L5-S1 compressive force (Fc) was predicted via a biomechanical model. A two-way multivariate analysis of variance (MANOVA) was performed to examine the effects of five blocks of lifting cycle (C1 to C5) and lifting trial (T1 to T5), as independent variables, on kinematic, kinetic, and EMG-related measures. RESULTS Significant effects of lifting trial blocks were found for CoM and CoP shift in the anterior-posterior direction (respectively p < .001 and p = .014), trunk angle (p = .004), vertical box displacement (p < .001), and Fc (p = .005). EMG parameters indicated muscular fatigue with the extent of changes being muscle-specific. CONCLUSION Results emphasized variations in most kinematics/kinetics, and EMG-based indices, which further provided insight into the lifting behavior adaptations under dynamic fatiguing conditions. APPLICATION Movement and muscle-related variables, to a large extent, determine the magnitude of spinal loading, which is associated with low back pain.
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Affiliation(s)
| | | | | | | | | | | | - Ramin Kordi
- 48439 Tehran University of Medical Sciences, Iran
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8
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Ramirez VJ, Bazrgari B, Gao F, Samaan M. Low Back Biomechanics during Repetitive Deadlifts: A Narrative Review. IISE Trans Occup Ergon Hum Factors 2022. [PMID: 34875981 DOI: 10.1080/24725838.2021.2015642] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
OCCUPATIONAL APPLICATIONSHeavy deadlifting is used as a screening tool or training protocol for recruitment and retention in physically-demanding occupations, especially in the military. Spinal loads experienced during heavy deadlifts, particularly shearing forces, are well above recommended thresholds for lumbar spine injury in occupational settings. Although members of the noted occupation likely have stronger musculoskeletal systems compared to the general population, experiencing shearing forces that are 2 to 4 times larger than the threshold of injury, particularly under repetitive deadlift, may transform a screening tool or training protocol to an occupationally-harmful physical activity.
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Affiliation(s)
| | - Babak Bazrgari
- Biomedical Engineering, University of Kentucky, Lexington, KY, USA
| | - Fan Gao
- Biomedical Engineering, University of Kentucky, Lexington, KY, USA
| | - Michael Samaan
- Biomedical Engineering, University of Kentucky, Lexington, KY, USA
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9
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Bauer J, Hagen M, Weisz N, Muehlbauer T. The Influence of Fatigue on Throwing and YBT-UQ Performance in Male Adolescent Handball Players. Front Sports Act Living 2020; 2:81. [PMID: 33345072 PMCID: PMC7739650 DOI: 10.3389/fspor.2020.00081] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Accepted: 05/28/2020] [Indexed: 11/13/2022] Open
Abstract
Purpose: The goal of the present study was to assess the effects of fatigue on throwing and Upper Quarter Y Balance Test (YBT-UQ) performance in male adolescent handball players. We hypothesized that throwing and YBT-UQ performance will be decreased in response to an upper-body fatigue-protocol. Method: All male participants (N = 24, age: 14.8 ± 0.7 yrs) were handball players of a regional youth selection team. A radar gun was used for the assessment of throwing velocity. The YBT-UQ was executed assessing medial, inferolateral and superolateral reach directions normalized to the upper limb length together with a composite score. Immediately following a fatigue protocol of different sets of push-ups until failure (i.e., not being able to perform 60% of the initial maximal amount of push-ups), throwing and YBT-UQ performance were assessed again. Results: Fatigue resulted in a significant decrease in throwing velocity (−3%, p = 0.022, d = 0.32). Concerning YBT-UQ, the fatigue protocol produced significant decreases for the superolateral reach direction (throwing arm reach: −5%, p = 0.017, d = 0.39; non-throwing arm reach: −10%, p < 0.001, d = 0.87) and the composite score (throwing arm reach: −2%, p = 0.026, d = 0.31; non-throwing arm reach: −4%, p = 0.001, d = 0.52) but not for the medial and the inferolateral reach directions. Conclusions: Fatigue was found to be an impairing factor for throwing performance and shoulder mobility and stability. Therefore, a lower level of fatigue and/or a higher tolerance of fatigue is desirable. Strength-endurance and mobility exercises especially for the shoulder girdle may be a valuable addition for the training routine of youth handball players.
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Affiliation(s)
- Julian Bauer
- Division of Movement and Training Sciences/Biomechanics of Sport, University of Duisburg-Essen, Essen, Germany
| | - Marco Hagen
- Division of Movement and Training Sciences/Biomechanics of Sport, University of Duisburg-Essen, Essen, Germany
| | - Nelson Weisz
- Division of Movement and Training Sciences/Biomechanics of Sport, University of Duisburg-Essen, Essen, Germany
| | - Thomas Muehlbauer
- Division of Movement and Training Sciences/Biomechanics of Sport, University of Duisburg-Essen, Essen, Germany
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Vazirian M, Shojaei I, Phillips M, Shapiro R, Bazrgari B. The immediate and prolonged effects of military body armor on the relative timing of thorax and pelvis rotations during toe-touch and two-legged squat tasks. J Biomech 2020; 111:110000. [PMID: 32858429 DOI: 10.1016/j.jbiomech.2020.110000] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2019] [Revised: 08/03/2020] [Accepted: 08/08/2020] [Indexed: 10/23/2022]
Abstract
Although military body armor is an effective life saver, it considerably loads more weight on the warfighters, increasing the risk of musculoskeletal injury. This study investigated the immediate and prolonged effects of wearing body armor on timing aspect of lumbo-pelvic coordination during the toe-touch (TT) and two-legged-squat (TLS) tests. A cross-over study design was used wherein twelve asymptomatic and gender-balanced individuals completed two experimental sessions with and without body armor. A session included two similar sets of tests, before and after exposure to a treadmill walk, containing a TT and a TLS test with ten cycles of fast bending and return. Reflective markers were attached on the participants to capture the kinematics of body segments in conjunction with a motion capture system. The mean absolute relative phase (MARP) and deviation phase (DP) between the thorax and pelvis were calculated for each test. The pre-walk MARP in the return was significantly larger with versus without body armor (p = 0.022), while there were no significant effects of body armor on the other outcome measures. In addition, the pre-walk MARP and DP in the bending and return, as well as the walk-induced changes in the MARP in the bending phase were significantly larger in TLS versus TT (p < 0.026). Therefore, using a body armor immediately made the lumbo-pelvic coordination less in-phase during return, but no prolonged effects were found. Further investigation is necessary to specify chances wearing a body armor increases the risk of musculoskeletal injuries in the lower back and lower extremities joints.
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Affiliation(s)
- Milad Vazirian
- F. Joseph Halcomb III, M.D. Department of Biomedical Engineering, University of Kentucky, Lexington, KY, USA
| | - Iman Shojaei
- F. Joseph Halcomb III, M.D. Department of Biomedical Engineering, University of Kentucky, Lexington, KY, USA
| | - Megan Phillips
- F. Joseph Halcomb III, M.D. Department of Biomedical Engineering, University of Kentucky, Lexington, KY, USA
| | - Robert Shapiro
- F. Joseph Halcomb III, M.D. Department of Biomedical Engineering, University of Kentucky, Lexington, KY, USA
| | - Babak Bazrgari
- F. Joseph Halcomb III, M.D. Department of Biomedical Engineering, University of Kentucky, Lexington, KY, USA.
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11
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Mulla DM, McDonald AC, Keir PJ. Joint moment trade-offs across the upper extremity and trunk during repetitive work. APPLIED ERGONOMICS 2020; 88:103142. [PMID: 32421639 DOI: 10.1016/j.apergo.2020.103142] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2019] [Revised: 04/28/2020] [Accepted: 05/01/2020] [Indexed: 06/11/2023]
Abstract
Individuals can coordinate small kinematic changes at several degrees of freedom simultaneously in the presence of fatigue, leaving it unclear how overall biomechanical demands at each joint are altered. The purpose of this study was to evaluate trade-offs in joint moments between the trunk, shoulder, and elbow during repetitive upper extremity work. Participants performed four simulated workplace tasks cyclically until meeting fatigue termination criteria. Emergent fatigue-induced adaptations to repetitive work resulted in task-dependent trade-offs in joint moments. In general, reduced shoulder moments were compensated for by increased elbow and trunk joint moment contributions. Although mean joint moment changes were modest (range: 1-3 Nm) across participants, a wide distribution of responses was observed, with standard deviations exceeding 10 Nm. Re-distributing biomechanical demands across joints may alleviate constant tissue loads and facilitate continued task performance with fatigue but may be at the expense of increasing demands at adjacent joints.
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Affiliation(s)
- Daanish M Mulla
- Department of Kinesiology, McMaster University, Hamilton, ON, Canada
| | - Alison C McDonald
- Department of Kinesiology, McMaster University, Hamilton, ON, Canada
| | - Peter J Keir
- Department of Kinesiology, McMaster University, Hamilton, ON, Canada.
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12
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Willwacher S, Koopmann T, Dill S, Kurz M, Brüggemann GP. Dorsal muscle fatigue increases thoracic spine curvature in all-out recreational ergometer rowing. Eur J Sport Sci 2020; 21:176-182. [DOI: 10.1080/17461391.2020.1737242] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Affiliation(s)
- Steffen Willwacher
- German Sport University Cologne, Institute of Biomechanics and Orthopaedics, Cologne, Germany
| | - Till Koopmann
- German Sport University Cologne, Institute of Biomechanics and Orthopaedics, Cologne, Germany
| | - Stephan Dill
- German Sport University Cologne, Institute of Biomechanics and Orthopaedics, Cologne, Germany
| | - Markus Kurz
- German Sport University Cologne, Institute of Biomechanics and Orthopaedics, Cologne, Germany
| | - Gert-Peter Brüggemann
- German Sport University Cologne, Institute of Biomechanics and Orthopaedics, Cologne, Germany
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13
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Pan F, Firouzabadi A, Zander T, Schmidt H. Sex-dependent differences in lumbo-pelvic coordination for different lifting tasks: A study on asymptomatic adults. J Biomech 2019; 102:109505. [PMID: 31761433 DOI: 10.1016/j.jbiomech.2019.109505] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Revised: 11/07/2019] [Accepted: 11/07/2019] [Indexed: 12/01/2022]
Abstract
During manual material lifting, the sagittal motion is mainly characterized through the lumbo-pelvic coordination, which is quantified by the ratio between the lumbar and hip rotations (L/P ratio). Alteration in the L/P ratio is an important indicator for low back pain (LBP). Previous studies demonstrated sex-dependent differences in LBP prevalence during lifting activities. However, the sex-dependent differences in the L/P ratio during different lifting tasks has to data not been investigated. An optoelectronic system was used to measure the sagittal lumbo-pelvic motion in 10 males and 10 females. Task A was lifting one weight from the ground in front of the body to three target heights with straight knees (A1-3: abdomen, chest and head levels, respectively). Task B was lifting two identical weights from the ground at the sides of the body to three target angles with bended knees (B1-3: arms close and 45° and 90° abducted to the trunk, respectively). Lifts of 10 kg (males and females) and 20 kg (males only) were performed and three phases were investigated: Phase 1 - pure flexion without load, Phase 2 - lifting up weights, Phase 3 - lowering down weights. Females generally displayed a smaller L/P ratio than males. In Phases 2 and 3, the L/P ratio was greater than in Phase 1 for Tasks A and B. The L/P ratio increased with a greater lifting height for Task B, but displayed no difference neither between lifting 10 kg and 20 kg, nor between weight lifting and lowering for both tasks. These results can provide indications for sex-specific recommendations for safer lifting activities.
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Affiliation(s)
- Fumin Pan
- Julius Wolff Institute, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Germany
| | - Ali Firouzabadi
- Julius Wolff Institute, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Germany
| | - Thomas Zander
- Julius Wolff Institute, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Germany
| | - Hendrik Schmidt
- Julius Wolff Institute, Charité - Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Germany.
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14
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Marino M. Impacts of Using Passive Back Assist and Shoulder Assist Exoskeletons in a Wholesale and Retail Trade Sector Environment. IISE Trans Occup Ergon Hum Factors 2019. [DOI: 10.1080/24725838.2019.1645057] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Affiliation(s)
- Matthew Marino
- Practice Lead for Wearable Technology & Exoskeletons – Ergonomics and Innovative Solutions Team, Briotix Health LP, Portland, USA
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15
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Towards a Grand Unified Theory of sports performance. Hum Mov Sci 2017; 56:139-156. [DOI: 10.1016/j.humov.2015.08.001] [Citation(s) in RCA: 73] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Revised: 06/17/2015] [Accepted: 08/04/2015] [Indexed: 12/22/2022]
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16
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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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Areeudomwong P, Oapdunsalam K, Havicha Y, Tantai S, Buttagat V. Effects of Shoulder Taping on Discomfort and Electromyographic Responses of the Neck While Texting on a Touchscreen Smartphone. Saf Health Work 2017; 9:319-325. [PMID: 30370164 PMCID: PMC6130209 DOI: 10.1016/j.shaw.2017.07.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2016] [Revised: 06/18/2017] [Accepted: 07/13/2017] [Indexed: 11/25/2022] Open
Abstract
Background Prolonged neck flexion during smartphone use is known as a factor of neck pain and alteration of neck muscle activity. Studies on the effects of shoulder taping on neck discomfort and neck muscle responses while texting on a smartphone are still lacking. The aim of this study was to examine the effects of shoulder taping on neck discomfort using a numerical rating scale, and neck muscle activity and fatigue using a surface electromyography during a texting task on a touchscreen smartphone. Methods Twenty-five healthy adolescents used the dominant hand to perform a 30-minute texting task using a touchscreen smartphone at two separate times under one of the following two conditions: taping across the upper trapezius muscle and no taping. Neck discomfort, normalized root mean square, and normalized median frequency slopes for upper trapezius, cervical erector spinae, and sternocleidomastoid muscles were recorded. Results The results revealed that shoulder taping provided significantly lower neck discomfort than no taping (p < 0.001). However, shoulder taping did not significantly alter normalized root mean square and normalized median frequency slope values of all muscles when compared with no taping controls. Conclusion Shoulder taping reduces neck discomfort but does not affect neck muscle activity and fatigue while texting on a touchscreen smartphone.
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Affiliation(s)
- Pattanasin Areeudomwong
- Department of Physical Therapy, School of Health Science, Mae Fah Luang University, Chiang Rai, Thailand.,Research Center in Back, Neck, Other Joint Pain and Human Performance, Khon Kaen University, Khon Kaen, Thailand
| | - Konnika Oapdunsalam
- Department of Physical Therapy, School of Health Science, Mae Fah Luang University, Chiang Rai, Thailand
| | - Yupadee Havicha
- Department of Physical Therapy, School of Health Science, Mae Fah Luang University, Chiang Rai, Thailand
| | - Sawit Tantai
- Department of Physical Therapy, School of Health Science, Mae Fah Luang University, Chiang Rai, Thailand
| | - Vitsarut Buttagat
- Department of Physical Therapy, School of Health Science, Mae Fah Luang University, Chiang Rai, Thailand.,Research Center in Back, Neck, Other Joint Pain and Human Performance, Khon Kaen University, Khon Kaen, Thailand
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Cowley JC, Gates DH. Proximal and distal muscle fatigue differentially affect movement coordination. PLoS One 2017; 12:e0172835. [PMID: 28235005 PMCID: PMC5325574 DOI: 10.1371/journal.pone.0172835] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Accepted: 02/10/2017] [Indexed: 11/19/2022] Open
Abstract
Muscle fatigue can cause people to change their movement patterns and these changes could contribute to acute or overuse injuries. However, these effects depend on which muscles are fatigued. The purpose of this study was to determine the differential effects of proximal and distal upper extremity muscle fatigue on repetitive movements. Fourteen subjects completed a repetitive ratcheting task before and after a fatigue protocol on separate days. The fatigue protocol either fatigued the proximal (shoulder flexor) or distal (finger flexor) muscles. Pre/Post changes in trunk, shoulder, elbow, and wrist kinematics were compared to determine how proximal and distal fatigue affected multi-joint movement patterns and variability. Proximal fatigue caused a significant increase (7°, p < 0.005) in trunk lean and velocity, reduced humeral elevation (11°, p < 0.005), and increased elbow flexion (4°, p < 0.01). In contrast, distal fatigue caused small but significant changes in trunk angles (2°, p < 0.05), increased velocity of wrench movement relative to the hand (17°/s, p < 0.001), and earlier wrist extension (4%, p < 0.005). Movement variability increased at proximal joints but not distal joints after both fatigue protocols (p < 0.05). Varying movements at proximal joints may help people adapt to fatigue at either proximal or distal joints. The identified differences between proximal and distal muscle fatigue adaptations could facilitate risk assessment of occupational tasks.
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Affiliation(s)
- Jeffrey C. Cowley
- School of Kinesiology, University of Michigan, Ann Arbor, Michigan, United States of America
| | - Deanna H. Gates
- School of Kinesiology, University of Michigan, Ann Arbor, Michigan, United States of America
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan, United States of America
- * E-mail:
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Fraser D, Potvin J, Jones J. Effects of Trunk Muscle Fatigue on Spine Mechanics during Repetitive Asymmetrical Lifting. ACTA ACUST UNITED AC 2016. [DOI: 10.1177/154193120004402861] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The purpose of this study was to determine the effects of repetitive lifting on trunk muscle activity and spine kinematics during an intense, forty minute, asymmetrical lifting and lowering task. Contrary to many previous sagittal plane materials handling studies, the asymmetrical task did result in differences in kinematics between lifting and lowering. Further, there were few consistent effects of fatigue on trunk muscle activity and only spine flexion was observed to decrease over the course of the trials. However, some individual subjects did demonstrate fatigue related changes that may have increased their risk of injury if performed over prolonged periods.
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Affiliation(s)
- Derek Fraser
- School of Human Kinetics, University of Windsor, Windsor, Ontario, Canada
| | - Jim Potvin
- School of Human Kinetics, University of Windsor, Windsor, Ontario, Canada
| | - Jeff Jones
- School of Human Kinetics, University of Windsor, Windsor, Ontario, Canada
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Ghesmaty Sangachin M, Cavuoto LA. Obesity-related changes in prolonged repetitive lifting performance. APPLIED ERGONOMICS 2016; 56:19-26. [PMID: 27184307 DOI: 10.1016/j.apergo.2016.03.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Revised: 12/31/2015] [Accepted: 03/04/2016] [Indexed: 06/05/2023]
Abstract
Despite the rising prevalence of obesity, little is known about its moderating effects on injury risk factors, such as fatigue, in occupational settings. This study investigated the effect of obesity, prolonged repetitive lifting and their interaction on lifting performance of 14 participants, 7 obese (mean body mass index (BMI): 33.2 kg m(-2)) and 7 non-obese (mean BMI: 22.2 kg m(-2)) subjects. To present a physically challenging task, subjects performed repetitive lifting for 1 h at 120% of their maximum acceptable weight of lift. Generalized linear mixed models were fit to posture and acceleration data. The obese group bent to a ∼10° lower peak trunk sagittal flexion angle, had 17% lower root mean square (RMS) jerk and took 0.8 s longer per lift. Over time, the obese group increased their trunk transverse and sagittal posterior accelerations while the non-obese maintained theirs. Although the majority of lifting variables were unaffected by BMI or its interaction with prolonged lifting duration, the observed differences, combined with a greater upper body mass, necessitate a more cautious use of existing psychophysical lifting limits for individuals who are obese, particularly when fatigued.
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Affiliation(s)
| | - Lora A Cavuoto
- Department of Industrial and Systems Engineering, University at Buffalo, Buffalo, NY, USA.
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21
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Frost DM, Beach TAC, Callaghan JP, McGill SM. Exercise-Based Performance Enhancement and Injury Prevention for Firefighters: Contrasting the Fitness- and Movement-Related Adaptations to Two Training Methodologies. J Strength Cond Res 2016; 29:2441-59. [PMID: 25763518 DOI: 10.1519/jsc.0000000000000923] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Using exercise to enhance physical fitness may have little impact on performers' movement patterns beyond the gym environment. This study examined the fitness and movement adaptations exhibited by firefighters in response to 2 training methodologies. Fifty-two firefighters were assigned to a movement-guided fitness (MOV), conventional fitness (FIT), or control (CON) group. Before and after 12 weeks of training, participants performed a fitness evaluation and laboratory-based test. Three-dimensional lumbar spine and frontal plane knee kinematics were quantified. Five whole-body tasks not included in the interventions were used to evaluate the transfer of training. FIT and MOV groups exhibited significant improvements in all aspects of fitness; however, only MOV exhibited improvements in spine and frontal plane knee motion control when performing each transfer task (effect sizes [ESs] of 0.2-1.5). FIT exhibited less controlled spine and frontal plane knee motions while squatting, lunging, pushing, and pulling (ES: 0.2-0.7). More MOV participants (43%) exhibited only positive posttraining changes (i.e., improved control), in comparison with FIT (30%) and CON (23%). Fewer negative posttraining changes were also noted (19, 25, and 36% for MOV, FIT, and CON). These findings suggest that placing an emphasis on how participants move while exercising may be an effective training strategy to elicit behavioral changes beyond the gym environment. For occupational athletes such as firefighters, soldiers, and police officers, this implies that exercise programs designed with a movement-oriented approach to periodization could have a direct impact on their safety and effectiveness by engraining desirable movement patterns that transfer to occupational tasks.
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Affiliation(s)
- David M Frost
- 1Faculty of Kinesiology and Physical Education, University of Toronto, Toronto, Ontario, Canada; and 2Department of Kinesiology, University of Waterloo, Waterloo, Ontario, Canada
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Mehta JP, Lavender SA, Jagacinski RJ, Sommerich CM. Effects of task precision demands on behavioral and physiological changes during a repetitive asymmetric lifting activity. HUMAN FACTORS 2015; 57:435-446. [PMID: 25875433 DOI: 10.1177/0018720814551556] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2014] [Accepted: 08/19/2014] [Indexed: 06/04/2023]
Abstract
OBJECTIVE This study investigated the effects of task precision demands on behavioral and physiological changes during repetitive asymmetric lifting. BACKGROUND Repetitive lifting encountered in manual material handling leads to muscle fatigue and is a documented risk factor for low back disorder. METHOD A total of 17 healthy volunteers performed repetitive asymmetric lifting for 60 min (10 lifts/min). Task precision demands were imposed by varying the entry width onto the destination conveyor. Physiological changes were assessed using near-infrared spectroscopy obtained from the erector spinae muscles. Three-dimensional spine kinematics and moment responses were quantified to understand behavioral changes during the lifting activity. RESULTS Task precision demands showed no effect on erector spinae muscle oxygenation levels. Behavioral changes associated with repetitive lifting included increases in the overall lift duration, peak forward bending motion, and three-dimensional movement velocities of the spine, along with a decrease in the lateral bending moment. Relative to low precision demands, high precision demands resulted in 20% longer placement periods, which, in turn, resulted in a 12% increase in the time-integrated twisting postures and a 10% increase in the time-integrated lateral bending moments during load placement. CONCLUSION The elevated risk of low back injury when lifting under greater precision demands is likely due to the sustained spine twisting and the sustained lateral bending moment on the spine in the final phase of these lifts. APPLICATION Understanding behavioral changes to repetitive asymmetric lifting, especially for tasks requiring greater precision can be used to support injury prevention efforts.
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Vieira MF, de Avelar IS, Silva MS, Soares V, Lobo da Costa PH. Effects of four days hiking on postural control. PLoS One 2015; 10:e0123214. [PMID: 25902060 PMCID: PMC4406731 DOI: 10.1371/journal.pone.0123214] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2014] [Accepted: 02/28/2015] [Indexed: 11/19/2022] Open
Abstract
Hiking is a demanding form of exercise that may cause delayed responses of the postural muscles and a loss of somatosensory information, particularly when repeatedly performed for several days. These effects may negatively influence the postural control of hikers. Therefore, the aim of this study was to investigate the effects of a four-day hike on postural control. Twenty-six adults of both sexes travelled 262 kilometers, stopping for lunch and resting in the early evening each day. Force platforms were used to collect center of pressure (COP) data at 100 Hz for 70 seconds before hiking started and immediately after arriving at the rest station each day. The COP time course data were analyzed according to global stabilometric descriptors, spectral analysis and structural descriptors using sway density curve (SDC) and stabilometric diffusion analysis (SDA). Significant increases were found for global variables in both the anterior-posterior and medial-lateral directions (COP sway area, COP total sway path, COP mean velocity, COP root mean square value and COP range). In the spectral analysis, only the 80% power frequency (F80) in the anterior-posterior direction showed a significant increase, reflecting the increase of the sway frequencies. The SDC revealed a significant increase in the mean distance between peaks (MD) and a significant decrease in the mean peak amplitudes (MP), suggesting that a larger torque amplitude is required for stabilization and that the postural stability is reduced. The SDA revealed a decrease in the long-term slope (Hl) and increases in the short-term (Ks) and the long-term (Kl) intercepts. We considered the likelihood that the presence of local and general fatigue, pain and related neuromuscular adaptations and somatosensory deficits may have contributed to these postural responses. Together, these results demonstrated that four days of hiking increased sway frequencies and deteriorated postural control in the standing position.
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Affiliation(s)
- Marcus Fraga Vieira
- Bioengineering and Biomechanics Laboratory, Universidade Federal de Goiás, Goiânia, Goiás, Brazil
- * E-mail:
| | - Ivan Silveira de Avelar
- Bioengineering and Biomechanics Laboratory, Universidade Federal de Goiás, Goiânia, Goiás, Brazil
| | - Maria Sebastiana Silva
- Bioengineering and Biomechanics Laboratory, Universidade Federal de Goiás, Goiânia, Goiás, Brazil
| | - Viviane Soares
- Bioengineering and Biomechanics Laboratory, Universidade Federal de Goiás, Goiânia, Goiás, Brazil
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24
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Boocock MG, Mawston GA, Taylor S. Age-related differences do affect postural kinematics and joint kinetics during repetitive lifting. Clin Biomech (Bristol, Avon) 2015; 30:136-43. [PMID: 25576019 DOI: 10.1016/j.clinbiomech.2014.12.010] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Revised: 11/19/2014] [Accepted: 12/19/2014] [Indexed: 02/07/2023]
Abstract
BACKGROUND Age is considered a risk factor for manual handling-related injuries and older workers incur higher injury-related costs than younger co-workers. This study investigated the differences between the kinematics and kinetics of repetitive lifting in two groups of handlers of different ages. METHODS Fourteen younger (mean 24.4 yr) and 14 older (mean 47.2 yr) males participated in the study. Participants repetitively lifted a box weighing 13 kg at a frequency of 10 lifts/min for a maximum of 20 min. Postural kinematics (joint and lumbosacral angles and angular velocities) and kinetics (joint moments) were measured throughout the lifting task using motion analysis and ground reaction forces. Muscle fatigue of the erector spinae was assessed using electromyography. FINDINGS Peak lumbosacral, trunk, hip and knee flexion angles differed significantly between age groups over the duration of the task, as did lumbosacral and trunk angular velocities. The younger group increased peak lumbar flexion by approximately 18% and approached 99% of maximum lumbosacral flexion after 20 min, whereas the older group increased lumbar flexion by 4% and approached 82% maximum flexion. The younger group had a larger increase in peak lumbosacral and trunk angular velocities during extension, which may be related to the increased back muscle fatigue observed among the younger group. INTERPRETATION Older participants appeared to control the detrimental effects of fatigue associated with repetitive lifting and limit lumbar spine range of motion. The higher rates of musculoskeletal injury among older workers may stem from a complex interaction of manual handling risk factors.
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Affiliation(s)
- Mark G Boocock
- Health and Rehabilitation Research Institute, Auckland University of Technology, New Zealand.
| | - Grant A Mawston
- Health and Rehabilitation Research Institute, Auckland University of Technology, New Zealand
| | - Steve Taylor
- Health and Rehabilitation Research Institute, Auckland University of Technology, New Zealand
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25
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Hu B, Ning X. The Changes of Trunk Motion Rhythm and Spinal Loading During Trunk Flexion and Extension Motions Caused by Lumbar Muscle Fatigue. Ann Biomed Eng 2015; 43:2112-9. [DOI: 10.1007/s10439-015-1248-0] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2014] [Accepted: 01/09/2015] [Indexed: 11/30/2022]
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Collier BR, Holland L, McGhee D, Sampson JA, Bell A, Stapley PJ, Groeller H. Precision markedly attenuates repetitive lift capacity. ERGONOMICS 2014; 57:1427-1439. [PMID: 25012299 DOI: 10.1080/00140139.2014.933885] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
UNLABELLED This study investigated the effect of precision on time to task failure in a repetitive whole-body manual handling task. Twelve participants were required to repetitively lift a box weighing 65% of their single repetition maximum to shoulder height using either precise or unconstrained box placement. Muscle activity, forces exerted at the ground, 2D body kinematics, box acceleration and psychophysical measures of performance were recorded until task failure was reached. With precision, time to task failure for repetitive lifting was reduced by 72%, whereas the duration taken to complete a single lift and anterior deltoid muscle activation increased by 39% and 25%, respectively. Yet, no significant difference was observed in ratings of perceived exertion or heart rate at task failure. In conclusion, our results suggest that when accuracy is a characteristic of a repetitive manual handling task, physical work capacity will decline markedly. PRACTITIONER SUMMARY The capacity to lift repetitively to shoulder height was reduced by 72% when increased accuracy was required to place a box upon a shelf. Lifting strategy and muscle activity were also modified, confirming practitioners should take into consideration movement precision when evaluating the demands of repetitive manual handling tasks.
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Affiliation(s)
- Brooke R Collier
- a Centre for Human and Applied Physiology, Faculty of Science, Medicine and Health , University of Wollongong , Wollongong , Australia
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27
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Mehta JP, Lavender SA, Jagacinski RJ. Physiological and biomechanical responses to a prolonged repetitive asymmetric lifting activity. ERGONOMICS 2014; 57:575-588. [PMID: 24552498 DOI: 10.1080/00140139.2014.887788] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
This study investigated the effects of a prolonged repetitive asymmetric lifting task on behavioural adaptations during repetitive lifting activity, measures of tissue oxygenation and spine kinematics. Seventeen volunteers repeatedly lifted a box, normalised to 15% of the participant's maximum lifting strength, at the rate of 10 lifts/min for a period of 60 min. The lifts originated in front of the participants at ankle level and terminated on their left side at waist level. Overall, perceived workload increased during the repetitive lifting task. Erector spinae oxygenation levels, assessed using near-infrared spectroscopy, decreased significantly over time. Behavioural changes observed during the repetitive lifting task included increases in the amount of forward bending, the extension velocity and the lateral bending velocity, and a reduced lateral bending moment on the spine. These changes, with the exception of the reduced lateral bending moment, are associated with increased risk of low back disorder.
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Affiliation(s)
- Jay P Mehta
- a Integrated Systems Engineering, The Ohio State University , 1971 Neil Avenue, Rm. 210, Columbus , OH 43210 , USA
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A randomized controlled trial of limited range of motion lumbar extension exercise in chronic low back pain. Spine (Phila Pa 1976) 2013; 38:1245-52. [PMID: 23514876 DOI: 10.1097/brs.0b013e318291b526] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
STUDY DESIGN Randomized controlled trial. OBJECTIVE To compare the effects of full range of motion (ROM) and limited ROM isolated lumbar extension exercise upon full ROM lumbar extension strength, ROM, perceived pain, and disability. SUMMARY OF BACKGROUND DATA Limited ROM is common in chronic low back pain as is lumbar extensor deconditioning. Limited ROM exercise is a common prescription but is yet to be empirically tested. METHODS Males (n = 21) and females (n = 17) with nonspecific chronic low back pain were initially recruited. Participants were randomized to either a full ROM (FullROM) or limited ROM (LimROM) training group or a control group. A total of 24 participants (males: n = 14, females: n = 10) completed the study and were included in analysis. The intervention lasted 12 weeks. FullROM and LimROM groups completed isolated lumbar extension resistance training once per week, performing one set of exercise at 80% of their maximal tested functional torque to failure. FullROM group trained through a full ROM. LimROM group trained through the mid 50% of their full ROM.Full ROM isolated lumbar extension strength, lumbar and standing ROM (Schobers test), perceived pain (visual analogue scale), and disability (Revised Oswestry Disability Index) were measured pre- and postintervention. RESULTS FullROM and LimROM significantly improved in full ROM lumbar extension strength, perceived pain, and disability compared with the control group. No changes occurred in lumbar or standing ROM. No significant differences were found between either FullROM or LimROM for any outcome measure. Changes in perceived pain and disability met minimal clinically important change values for FullROM (visual analogue scale, -30.3 + 25.76 mm and Oswestry Disability Index, -18.2 + 6.63 patients) and LimROM (visual analogue scale, -16.29 + 10.97 mm and Oswestry Disability Index, -12 + 5.16 patients). CONCLUSION The results suggest that both FullROM and LimROM are equally effective in increasing full ROM lumbar extension strength and producing clinically meaningful improvement in perceived pain and disability.
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Gender Differences in Trunk and Pelvic Kinematics During Prolonged Ergometer Rowing in Adolescents. J Appl Biomech 2013; 29:180-7. [DOI: 10.1123/jab.29.2.180] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The trunk and pelvis kinematics of 20 healthy male and female adolescent rowers were recorded during an ergometer trial using an electromagnetic tracking system (Fastrak). The kinematics of each drive phase were collected during the 1st and 20th minute, respectively. The mean and range of the kinematics, stroke rate and stroke length were compared between genders and over time. Male rowers postured their pelvis with more posterior tilt and their thoracic spine in more flexion than female rowers (P< .05). Both genders postured their pelvis in more posterior pelvic rotation and upper trunk in more flexion over time. Male rowers were found to have a significantly shorter drive phase than female rowers (P= .001). Differences in trunk and pelvic kinematics between adolescent male and female rowers suggest potentially various mechanisms for biomechanical stress. Assessment and training of rowers should take gender differences into consideration.
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Srinivasan D, Mathiassen SE. Motor variability in occupational health and performance. Clin Biomech (Bristol, Avon) 2012; 27:979-93. [PMID: 22954427 DOI: 10.1016/j.clinbiomech.2012.08.007] [Citation(s) in RCA: 171] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/10/2012] [Revised: 08/13/2012] [Accepted: 08/16/2012] [Indexed: 02/07/2023]
Abstract
Several recent reviews have reported that 'repetitive movements' constitute a risk factor for occupational musculoskeletal disorders in the neck, shoulder and arm regions. More variation in biomechanical exposure is often suggested as an effective intervention in such settings. Since increasing variation using extrinsic methods like job rotation may not always be possible in an industrial context, the intrinsic variability of the motor system may offer an alternative opportunity to increase variation. Motor variability refers to the natural variation in postures, movements and muscle activity observed to different extents in all tasks. The current review discusses research appearing in motor control, sports sciences and occupational biomechanics literature to answer whether motor variability is important to consider in an occupational context, and if yes, whether it can be manipulated by training the worker or changing the working conditions so as to increase biomechanical variation without jeopardizing production. The review concludes that motor variability is, indeed, a relevant issue in occupational health and performance and suggests a number of key issues for further research.
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Affiliation(s)
- Divya Srinivasan
- Centre for Musculoskeletal Research, Department of Occupational and Public Health Sciences, University of Gavle, 801 76 Gavle, Sweden.
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31
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Paillard T. Effects of general and local fatigue on postural control: A review. Neurosci Biobehav Rev 2012; 36:162-76. [DOI: 10.1016/j.neubiorev.2011.05.009] [Citation(s) in RCA: 227] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2011] [Revised: 05/13/2011] [Accepted: 05/19/2011] [Indexed: 12/19/2022]
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Fuller JR, Fung J, Côté JN. Time-dependent adaptations to posture and movement characteristics during the development of repetitive reaching induced fatigue. Exp Brain Res 2011; 211:133-43. [DOI: 10.1007/s00221-011-2661-8] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2010] [Accepted: 03/24/2011] [Indexed: 10/18/2022]
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Gates DH, Dingwell JB. The effects of muscle fatigue and movement height on movement stability and variability. Exp Brain Res 2011; 209:525-36. [DOI: 10.1007/s00221-011-2580-8] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2010] [Accepted: 01/28/2011] [Indexed: 11/29/2022]
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34
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Lomond KV, Côté JN. Differences in posture-movement changes induced by repetitive arm motion in healthy and shoulder-injured individuals. Clin Biomech (Bristol, Avon) 2011; 26:123-9. [PMID: 20950902 DOI: 10.1016/j.clinbiomech.2010.09.012] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/13/2009] [Revised: 04/28/2010] [Accepted: 09/16/2010] [Indexed: 02/07/2023]
Abstract
BACKGROUND Neck/Shoulder pain is linked to movement repetition, awkward postures, prolonged maintenance of static postures, and muscular fatigue. Studies have examined the influence of pain and fatigue on movement characteristics, but few reported multi-dimensional adaptations to movement repetition. We compared the adaptations measured in three-dimensions during a repetitive reaching task in persons with chronic neck/shoulder pain and healthy subjects. METHODS A shoulder-injured group (intensity >3/10, duration >3 consecutive months) and an age-sex-matched control group (n=16 in each) performed a repetitive reaching task to voluntary termination. Kinematics, kinetics, heart rate and muscle activity were recorded throughout. Power output on a 10-s pushing/pulling task was assessed pre- and post-reaching. Group comparisons were made in absolute time and at task end. FINDINGS Control subjects performed the task 55% longer than the pain group; yet, both groups demonstrated task-related increased heart rate (6 beats per minute) and decreased power output (6 W). Throughout the task, the pain group demonstrated: higher supraspinatus activity, and less elbow flexion and endpoint movement. The control group increased movement amplitude of the endpoint, elbow, and shoulder, while the pain group moved the shoulder less and increased center of mass excursion to maintain the task. INTERPRETATION Both groups adapted to the task in unique ways. The control group continually increased elbow and endpoint range of motion, bringing the arm closer to the targets, possibly to prolong task performance. The pain group used a fixed, en block arm strategy, likely to reduce the load on the injured structures; however, this may place other structures at risk for pain and injury.
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Affiliation(s)
- Karen V Lomond
- Department of Kinesiology and Physical Education, McGill University, Montreal, Quebec, Canada.
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Lomond KV, Côté JN. Movement timing and reach to reach variability during a repetitive reaching task in persons with chronic neck/shoulder pain and healthy subjects. Exp Brain Res 2010; 206:271-82. [DOI: 10.1007/s00221-010-2405-1] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2010] [Accepted: 08/25/2010] [Indexed: 10/19/2022]
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Abstract
STUDY DESIGN Intervention study on healthy human subjects. OBJECTIVE To determine whether reflex activation of the back muscles is influenced by muscle fatigue or soft tissue creep in the spine. SUMMARY OF BACKGROUND DATA Reflex contraction of the back muscles normally acts to limit spinal flexion, and hence protect the underlying spine from injury. However, repeated flexion allows bending moments on the spine to increase. Impaired reflexes as a result of fatigue or soft tissue creep may be contributing factors. METHODS A total of 15 healthy volunteers (8 females/7 males aged 23-55 years) underwent 2 interventions, on separate days: (a) sitting flexed for 1 hour to induce creep and (b) performing the Biering-Sorensen test to induce back muscle fatigue. Before and after each intervention, reflex activation of the erector spinae in response to sudden trunk flexion (initiated by a Kin-Com dynamometer) was monitored bilaterally at T10 and L3 using surface electromyography (EMG) electrodes. These recordings indicated the onset latency of reflex activation, the peak EMG, and time to peak, at each site. Measurements before and after each intervention and between muscle sites were compared using a 2-way repeated measures Analysis of Variance. RESULTS Spinal creep was confirmed by an increase in maximum flexion of 2.3 degrees +/- 2.5 degrees (P = 0.003), and fatigue by a significant fall in median frequency at one or more sites. Following creep, onset latency increased from 60 +/- 12 milliseconds to 96 +/- 26 milliseconds (P < 0.001) but there was no change in peak EMG or time to peak EMG. Differences between sites (P = 0.004) indicated greater latencies in lumbar compared to thoracic regions, especially after creep. Muscle fatigue had no significant effects on any of the measured parameters. CONCLUSION Prolonged spinal flexion can impair sensorimotor control mechanisms and reduce back muscle protection of the underlying spine. The effect is due to time-dependent "creep" in soft tissues rather than muscle fatigue.
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Frost DM, Abdoli-E M, Stevenson JM. PLAD (personal lift assistive device) stiffness affects the lumbar flexion/extension moment and the posterior chain EMG during symmetrical lifting tasks. J Electromyogr Kinesiol 2009; 19:e403-12. [DOI: 10.1016/j.jelekin.2008.12.002] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2008] [Revised: 12/16/2008] [Accepted: 12/16/2008] [Indexed: 11/25/2022] Open
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Li K, Zhang X. Can relative strength between the back and knees differentiate lifting strategy? HUMAN FACTORS 2009; 51:785-796. [PMID: 20415155 DOI: 10.1177/0018720809360801] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
OBJECTIVE This study investigated whether relative strength between the back and knees can differentiate and predict lifting strategy and the effects of gender, load magnitude, and knowledge of strength on the strategy. BACKGROUND Although muscular strength is thought to play a vital role in the mechanics of lifting, how localized joint strengths and their relations influence lifting strategy remains unclear. METHOD Thirty-two participants (16 men and 16 women) underwent isokinetic strength tests and were then divided into two groups: one provided with the knowledge of their strength test results and the other not. They subsequently performed the same set of simulated lifting tasks while their lifting kinematics were being recorded. Postural indices to quantify the lifting strategies were derived from the kinematic data. RESULTS The ratio of back strength versus total knee strength and gender had significant effects on measures quantifying the lifting strategy. A statistical model incorporating gender, strength, and anthropometry achieved an R2 value of .64 and predicted correctly 76% of lifting strategies used by individual participants. CONCLUSION Individuals with back strength greater than their total knee strength tended to use a back-preferred lift strategy, and vice versa, suggesting that muscular strength is a determining factor of lifting strategy. APPLICATION An emphasis on additional knee strengthening in a training program may change the tendency of using and overstressing the back. APPLICATION of modeling and simulation technology for ergonomics design can be enhanced by more individually and accurately specified lifting strategies based on anthropometry and strength profiles.
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Affiliation(s)
- Kang Li
- University of Illinois at Urbana-Champaign, USA
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Fuller JR, Lomond KV, Fung J, Côté JN. Posture-movement changes following repetitive motion-induced shoulder muscle fatigue. J Electromyogr Kinesiol 2009; 19:1043-52. [DOI: 10.1016/j.jelekin.2008.10.009] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2008] [Revised: 10/13/2008] [Accepted: 10/14/2008] [Indexed: 10/21/2022] Open
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Trunk muscle activation during sub-maximal extension efforts. ACTA ACUST UNITED AC 2009; 15:105-10. [PMID: 19716741 DOI: 10.1016/j.math.2009.08.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2008] [Revised: 07/28/2009] [Accepted: 08/06/2009] [Indexed: 11/22/2022]
Abstract
Neuromuscular fatigue of the trunk musculature, particularly lumbar paraspinal and abdominal muscles, is important in when evaluating motor control of the trunk. Activation of agonists and antagonists trunk muscles was hypothesized to change during sub-maximal isometric trunk extension efforts. Thirteen women were positioned in 30 degrees of trunk flexion and performed maximal voluntary isometric contraction in trunk extension against an isokinetic dynamometer. One of two sub-maximal efforts (50% and 70%) was performed to induce neuromuscular fatigue on two different days. Surface electromyography of the lumbar paraspinal (LP), rectus abdominis, and external oblique muscles was recorded during each session. Torque output, median frequency of the power density spectrum, and normalized integrated electromyography were analyzed using repeated measures analysis of variance to evaluate trends in the data over time. Paraspinal muscles showed signs of fatigue in both conditions (p<0.05) Abdominal activity did not increase during the 70% condition, but showed a non-significant trend (p=0.07), coinciding with the reduced median frequency of LP muscles. The neuromuscular system modulates its motor control strategy to identify the muscle activation levels necessary to maintain force output. This information is necessary in the evaluation of contributing mechanisms to trunk stability in furthering preventative and rehabilitative treatments.
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Dingwell JB, Joubert JE, Diefenthaeler F, Trinity JD. Changes in muscle activity and kinematics of highly trained cyclists during fatigue. IEEE Trans Biomed Eng 2009; 55:2666-74. [PMID: 18990638 DOI: 10.1109/tbme.2008.2001130] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Muscle fatigue may alter kinematics and contribute to repetitive strain injuries. This study quantified how both localized muscle fatigue and movement kinematics change over time during exhaustive cycling. Seven highly trained cyclists rode a stationary bicycle ergometer at 100% of their maximum oxygen consumption (VO(2) max) until voluntary exhaustion. Cycling kinematics and electromyography (EMG) activity from select lower extremity muscles were recorded. Cross-correlations were computed to quantify how EMG median frequencies (MDFs) changed with changes in movement kinematics. All athletes maintained both cadence and power output for approximately 90% of the trial duration. Significant sustained muscle fatigue occurred in 18 of 28 muscles tested, most prominently in the biceps femoris (p = 0.020) and gastrocnemius (p = 0.018). Kinematics and MDF both fluctuated nonmonotonically as subjects fatigued. Changes in MDF significantly preceded changes in mean trunk lean (p = 0.009) and hip angles (p = 0.025), and trunk lean range of motion ( p = 0.029). Fluctuations in MDF were positively correlated with fluctuations in mean trunk lean (p = 0.009) and knee splay angles (p = 0.011), and with trunk lean (p = 0.002) and ankle (p = 0.001) range of motion. These results therefore establish a direct link between changes in muscle fatigue state and subsequent changes in movement kinematics during cycling.
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Song M, Segala DB, Dingwell JB, Chelidze D. Slow-time changes in human EMG muscle fatigue states are fully represented in movement kinematics. J Biomech Eng 2009; 131:021004. [PMID: 19102563 DOI: 10.1115/1.3005177] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The ability to identify physiologic fatigue and related changes in kinematics can provide an important tool for diagnosing fatigue-related injuries. This study examined an exhaustive cycling task to demonstrate how changes in movement kinematics and variability reflect underlying changes in local muscle states. Motion kinematics data were used to construct fatigue features. Their multivariate analysis, based on smooth orthogonal decomposition, was used to reconstruct physiological fatigue. Two different features composed of (1) standard statistical metrics (SSM), which were a collection of standard long-time measures, and (2) phase space warping (PSW)-based metrics, which characterized short-time variations in the phase space trajectories, were considered. Movement kinematics and surface electromyography (EMG) signals were measured from the lower extremities of seven highly trained cyclists as they cycled to voluntary exhaustion on a stationary bicycle. Mean and median frequencies from the EMG time series were computed to measure the local fatigue dynamics of individual muscles independent of the SSM- and PSW-based features, which were extracted solely from the kinematics data. A nonlinear analysis of kinematic features was shown to be essential for capturing full multidimensional fatigue dynamics. A four-dimensional fatigue manifold identified using a nonlinear PSW-based analysis of kinematics data was shown to adequately predict all EMG-based individual muscle fatigue trends. While SSM-based analyses showed similar dominant global fatigue trends, they failed to capture individual muscle activities in a low-dimensional manifold. Therefore, the nonlinear PSW-based analysis of strictly kinematic time series data directly predicted all of the local muscle fatigue trends in a low-dimensional systemic fatigue trajectory. These results provide the first direct quantitative link between changes in muscle fatigue dynamics and resulting changes in movement kinematics.
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Affiliation(s)
- Miao Song
- Nonlinear Dynamics Laboratory, Department of Mechanical Engineering and Applied Mechanics, University of Rhode Island, Kingston, RI 02881
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Hsu CJ, Chang YW, Chou WY, Chiou CP, Chang WN, Wong CY. Measurement of spinal range of motion in healthy individuals using an electromagnetic tracking device. J Neurosurg Spine 2008; 8:135-42. [DOI: 10.3171/spi/2008/8/2/135] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Object
The authors measured the range of motion (ROM) of the spine in healthy individuals by using an electromagnetic tracking device to evaluate the functional performance of the spine.
Methods
The authors used the Flock of Birds electromagnetic tracking device with 4 receiver units attached to C-7, T-12, S-1, and the midthigh region. Forward/backward bending, bilateral side bending, and axial rotation of the trunk were performed in 18 healthy individuals.
Results
The average ROM was calculated after 3 consecutive measurements. The thoracic spine generated the greatest angle in axial rotation and smallest angle in backward bending. The lumbar spine generated the greatest angle in forward bending and smallest angle in axial rotation. The hip joints generated the greatest angle in forward bending and smallest angle in backward bending. Additionally, 40% of forward-bending motion occurred in the lumbar spine and 40% occurred in the hip joints. Approximately 60% of backward bending occurred in the lumbar spine; 60% of axial rotation occurred in the thoracic spine; and 45% of side bending occurred in the thoracic spine.
Conclusions
The Flock of Birds electromagnetic tracking device cannot only measure the ROM of spine but also easily differentiate the 6-degree contributions by different segments.
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Affiliation(s)
- Chien-Jen Hsu
- 1Department of Nursing, I-Shou University, Kaohsiung Hsien
- 2Department of Orthopedics, Kaohsiung Veterans General Hospital
| | - Yi-Wen Chang
- 3Department of Exercise and Health Science, National Taiwan College of Physical Education, Taichung; and
| | - Wen-Ying Chou
- 4Department of Anesthesiology, Chang-Gung Memorial Hospital, Kaohsiung Medical Center, Chang-Gung University College of Medicine, Kaohsiung, Taiwan
| | | | - Wei-Ning Chang
- 2Department of Orthopedics, Kaohsiung Veterans General Hospital
| | - Chi-Yin Wong
- 2Department of Orthopedics, Kaohsiung Veterans General Hospital
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Sasaki M, Horio A, Wakasa M, Uemura S, Osawa Y. Influence of Quadriceps Femoris Fatigue on Low Back Load during Lifting of Loads at Different Distances from the Toes. J Phys Ther Sci 2008. [DOI: 10.1589/jpts.20.81] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Affiliation(s)
- Makoto Sasaki
- Course of Physical Therapy, School of Health Sciences, Akita University
| | - Akira Horio
- Department of Rehabilitation, Chiba Central Medical Center
| | - Masahiko Wakasa
- Course of Physical Therapy, School of Health Sciences, Akita University
| | - Sachiko Uemura
- Course of Physical Therapy, School of Health Sciences, Akita University
| | - Yukihiko Osawa
- Course of Physical Therapy, School of Health Sciences, Akita University
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Liu JZ, Lewandowski B, Karakasis C, Yao B, Siemionow V, Sahgal V, Yue GH. Shifting of activation center in the brain during muscle fatigue: an explanation of minimal central fatigue? Neuroimage 2007; 35:299-307. [PMID: 17236789 PMCID: PMC2701907 DOI: 10.1016/j.neuroimage.2006.09.050] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2006] [Revised: 09/20/2006] [Accepted: 09/25/2006] [Indexed: 11/17/2022] Open
Abstract
Accumulating evidence suggests that the overall level of cortical activation controlling a voluntary motor task that leads to significant muscle fatigue does not decrease as much as the activation level of the motoneuron pool projecting to the muscle. One possible explanation for this "muscle fatigue>cortical fatigue" phenomenon is that the brain is an organ with built-in redundancies: it has multiple motor centers and parallel pathways, and the center of activation may shift from one location to another when neurons in the previous location become fatigued. This hypothesis was tested by estimating the changes of source locations of high-density (64 channels) scalp electroencephalographic (EEG) signals collected during both fatigue and non-fatigue motor tasks. A current dipole model was used to estimate the EEG sources. The fatigue motor task induced significant muscle fatigue, and the non-fatigue task did not. The EEG signal source that indicated the center of brain activation showed substantial location shifts during the fatigue motor task. The shifts could not be explained by variations of source locations caused by error estimated from the non-fatigue task EEG and simulated data. Compared to the non-fatigue condition, the weighted-center of the source locations for all the participants shifted toward the right hemisphere (ipsilateral to the muscle activation), anterior, and inferior cortical regions under the fatigue condition. Fatigue did not alter dipole (source-signal) strength or the overall level of brain activation. The brain may avoid fatigue by shifting neuron populations that participate in a fatiguing motor task.
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Affiliation(s)
- Jing Z. Liu
- Department of Biomedical Engineering, The Cleveland Clinic Foundation, Cleveland, Ohio 44195
- Department of Physics, Case Western Reserve University, Cleveland, Ohio 44106
| | - Beth Lewandowski
- Department of Biomedical Engineering, The Cleveland Clinic Foundation, Cleveland, Ohio 44195
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio 44106
| | - Chris Karakasis
- Department of Biomedical Engineering, The Cleveland Clinic Foundation, Cleveland, Ohio 44195
| | - Bing Yao
- Department of Biomedical Engineering, The Cleveland Clinic Foundation, Cleveland, Ohio 44195
- Department of Physics, Case Western Reserve University, Cleveland, Ohio 44106
| | - Vlodek Siemionow
- Department of Biomedical Engineering, The Cleveland Clinic Foundation, Cleveland, Ohio 44195
- Department of Physical Medicine & Rehabilitation, The Cleveland Clinic Foundation, Cleveland, Ohio 44195
| | - Vinod Sahgal
- Department of Physical Medicine & Rehabilitation, The Cleveland Clinic Foundation, Cleveland, Ohio 44195
| | - Guang H. Yue
- Department of Biomedical Engineering, The Cleveland Clinic Foundation, Cleveland, Ohio 44195
- Department of Physical Medicine & Rehabilitation, The Cleveland Clinic Foundation, Cleveland, Ohio 44195
- Department of Biomedical Engineering, Case Western Reserve University, Cleveland, Ohio 44106
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Kim KH, Gillespie RB, Martin BJ. Head movement control in visually guided tasks: postural goal and optimality. Comput Biol Med 2006; 37:1009-19. [PMID: 17067566 DOI: 10.1016/j.compbiomed.2006.08.019] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2005] [Revised: 07/18/2006] [Accepted: 08/03/2006] [Indexed: 10/24/2022]
Abstract
This work investigates the control of horizontal head movements in the context of unconstrained visually guided head and arm/finger aiming tasks. In a first experiment, the head was free to move while gaze was directed at randomly presented eccentric targets distributed horizontally (0 degrees-120 degrees) at eye level. In a second experiment, the horizontal head orientation was constrained to predetermined positions (0 degrees, 15 degrees, 30 degrees, 45 degrees or 60 degrees rightward) while the right index finger aimed at targets with the arm fully extended. Kinematics of head movements in gaze displacements exhibits an initial component weakly correlated with target position, followed by multiple corrections. Since the eyes are assumed to already be aimed at the target when the corrections occur, it is suggested that one goal of head movement control is to achieve a desired final orientation (posture). This hypothesis is supported by results from the second experiment that reveal an association between eye/head orientation angles and errors exhibited in the visuo-spatial representation of the environment. The minimization of error then underlies the control of head movement as a postural response optimized for a given target and task condition.
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Affiliation(s)
- K Han Kim
- Human Motion Simulation Laboratory, Center for Ergonomics, The University of Michigan, 1205 Beal Avenue, Ann Arbor, MI 48109-2117, USA
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Marras WS, Parakkat J, Chany AM, Yang G, Burr D, Lavender SA. Spine loading as a function of lift frequency, exposure duration, and work experience. Clin Biomech (Bristol, Avon) 2006; 21:345-52. [PMID: 16310299 DOI: 10.1016/j.clinbiomech.2005.10.004] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/04/2005] [Revised: 10/03/2005] [Accepted: 10/05/2005] [Indexed: 02/07/2023]
Abstract
BACKGROUND Physiological and psychophysical studies of the effects of lifting frequency have focused on whole-body measurements of fatigue or subjective acceptance of the task and have not considered how spine loads may change as a function of lift frequency or lift time exposure. Our understanding of biomechanical spine loading has been extrapolated from short lifting bouts to the entire work day and may have led us to incorrect assumptions. The objective of this project was to document how spine loading changes as a function of experience, lift frequency, and lift duration while repetitively lifting over the course of an 8-h workday. METHODS Twelve novice and twelve experienced manual materials handlers performed repetitive, asymmetric lifts at different load and lift frequency levels throughout an 8-h exposure period. Compression, anterior-posterior shear, and lateral shear were evaluated over the lifting period using an EMG-assisted biomechanical model. RESULTS Spinal loads increased after the first 2 h of lifting exposure regardless of the lift frequency. Loading was also greater for the inexperienced subjects compared to experienced lifters. The greatest spine loads occurred at those lift frequencies and weights to which the workers were unaccustomed. INTERPRETATION Increases in spine loading were tracked back to the changes in muscle recruitment patterns that typically involved increased muscle coactivation. The results emphasize the importance of previous motor programming in defining spine loads during repetitive lifting. These results indicate a very different influence of frequency and lift time exposure compared to physiologic and psychophysical assessments. This study has shown that it is not sufficient to extrapolate from short lift periods to extended exposure periods if the biomechanical loading implications of the task are of interest.
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Affiliation(s)
- W S Marras
- Biodynamics Laboratory, The Ohio State University, Columbus, 43210, USA.
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Schmid M, Schieppati M, Pozzo T. Effect of fatigue on the precision of a whole-body pointing task. Neuroscience 2006; 139:909-20. [PMID: 16504410 DOI: 10.1016/j.neuroscience.2005.12.060] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2005] [Revised: 12/20/2005] [Accepted: 12/27/2005] [Indexed: 10/25/2022]
Abstract
We addressed the issue of the possible degradation of the aiming precision of a whole-body pointing task, when movement coordination is deranged by selective fatigue of the postural task component. The protocol involved continuous repetition (0.1 Hz frequency) of rapid whole-body pointing trials toward a target located beyond arm length, starting from stance and requiring knee flexion. Six healthy human subjects repeated the trials until exhaustion. Such repetition led to electromyography signs of fatigue in rectus femoris (active in body lowering and raising), but not in deltoid (prime mover for arm reaching component). Rectus femoris fatigue affected the equilibrium control strategy, since the anteroposterior displacement of the center of foot pressure was reduced during the fatigued compared with the initial trials. Conversely, the precision of the aiming movement was unaffected by the rectus femoris fatigue in spite of changes in finger trajectory. Trunk inclination at the end of whole-body pointing task and hip and shoulder marker trajectories were unaffected by rectus femoris fatigue. Control experiments were made, whereby fatiguing repetitions of the postural component of the task were performed without finger pointing, except in the first and last five complete whole-body pointing trials. The results were not different from those of the main protocol, except for a transient change in finger trajectory in the very first trial after fatigue. The CNS takes into account the state of postural muscles' fatigue and the concurrently ensuing equilibrium constraints in order to appropriately modify whole-body pointing strategy and keep pointing precision at the target.
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Affiliation(s)
- M Schmid
- Human Movement Laboratory, Fondazione Salvatore Maugeri, Scientific Institute of Pavia, Via Ferrata 8, I-27100 Pavia, Italy.
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Albert WJ, Wrigley AT, McLean RB, Sleivert GG. Sex differences in the rate of fatigue development and recovery. DYNAMIC MEDICINE : DM 2006; 5:2. [PMID: 16412256 PMCID: PMC1368970 DOI: 10.1186/1476-5918-5-2] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/04/2005] [Accepted: 01/16/2006] [Indexed: 02/03/2023]
Abstract
Background Many musculoskeltal injuries in the workplace have been attributed to the repetitive loading of muscle and soft tissues. It is not disputed that muscular fatigue is a risk factor for musculoskeltal injury, however the disparity between gender with respect to muscular fatigability and rate of recovery is not well understood. Current health and safety guidelines do not account for sex differences in fatiguability and may be predisposing one gender to greater risk. The purpose of this study was to quantify the sex differences in fatigue development and recovery rate of lower and upper body musculature after repeated bouts of sustained isometric contractions. Methods Twenty-seven healthy males (n = 12) and females (n = 15) underwent bilateral localized fatigue of either the knee extensors (male: n = 8; female: n = 8), elbow flexors (male: n = 8; female: n = 10), or both muscle groups. The fatigue protocol consisted of ten 30-second sub-maximal isometric contractions. The changes in maximum voluntary contraction (MVC), electrically evoked twitches, and motor unit activation (MUA) were assessed along with the ability to control the sustained contractions (SLP) during the fatigue protocol using a mixed four-factor repeated measures ANOVA (gender × side × muscle × time) design with significance set at p < 0.05. Results There was a significant loss of MVC, MUA, and evoked twitch amplitude from pre- to post-fatigue in both the arms and legs. Males had greater relative loss of isometric force, a higher rate of fatigue development, and were less capable of maintaining the fatiguing contractions in the legs when compared to the females. Conclusion The nature of the induced fatigue was a combination of central and peripheral fatigue that did not fully recover over a 45-minute period. The results appear to reflect sex differences that are peripheral, and partially support the muscle mass hypothesis for explaining differences in muscular fatigue.
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Affiliation(s)
- WJ Albert
- Human Performance Laboratory, Faculty of Kinesiolgy, University of New Brunswick, Fredericton, New Brunswick, Canada
| | - AT Wrigley
- Human Performance Laboratory, Faculty of Kinesiolgy, University of New Brunswick, Fredericton, New Brunswick, Canada
| | - RB McLean
- Human Performance Laboratory, Faculty of Kinesiolgy, University of New Brunswick, Fredericton, New Brunswick, Canada
| | - GG Sleivert
- PacificSport, Canadian Sport Centre, Victoria, British Columbia, Canada
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