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Larson DJ, Summers E, Brown SHM. Exploring how metronome pacing at varying movement speeds influences local dynamic stability and coordination variability of lumbar spine motion during repetitive lifting. Hum Mov Sci 2024; 93:103178. [PMID: 38217964 DOI: 10.1016/j.humov.2024.103178] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Revised: 12/20/2023] [Accepted: 01/06/2024] [Indexed: 01/15/2024]
Abstract
Auditory metronomes have been used to preserve movement consistency when examining local dynamic stability (LDS) and coordination variability (CV) of lumbar spine motion during repetitive movements. However, the potential influence of the metronome itself on these outcome measures has rarely been considered. Therefore, this study investigated the influence of different metronome paces (i.e., lifting speeds) on measures of lumbar spine LDS and thorax-pelvis CV during a repetitive lifting/lowering task in comparison to self-paced movements. Ten participants completed 5 repetitive lift/lower trials, where participants completed 35 consecutive repetitions (analysis on last 30 repetitions) at a self-selected pace for the first and last trial, and were paced by a 10 lift/min, 15 lift/min, and 20 lift/min metronome, in randomized order, for the remaining three trials. The average self-paced lift/lower speed before and after experiencing the three different metronome paced speeds was 16.2 (±1.02) and 17.2 (±0.73) lifts/min, respectively, and the most-preferred metronome pace trial was 15 lifts/min. Thorax-pelvis CV during the self-paced trials were similar (p > 0.05) to the 15 lift/min metronome paced trials, while greater thorax-pelvis CV was observed for the 10 lift/min compared to the 15 lift/min and 20 lift/min and second self-paced trial (all p < 0.026). This movement speed effect was not observed for lumbar spine LDS; however, more-dynamically stable movements were observed during all metronome paced trials in comparison to the self-paced trials. This study highlights that careful consideration is required when employing a metronome to control/manipulate movement characteristics while examining neuromuscular control using non-linear dynamical systems measures.
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Affiliation(s)
- Dennis J Larson
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada; Department of Kinesiology, University of Waterloo, Waterloo, ON, Canada
| | - Elspeth Summers
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada
| | - Stephen H M Brown
- Department of Human Health and Nutritional Sciences, University of Guelph, Guelph, ON, Canada.
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Trunk stability in fatiguing frequency-dependent lifting activities. Gait Posture 2023; 102:72-79. [PMID: 36934473 DOI: 10.1016/j.gaitpost.2023.03.001] [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] [Received: 09/01/2022] [Revised: 11/30/2022] [Accepted: 03/06/2023] [Indexed: 03/21/2023]
Abstract
BACKGROUND Work-related low-back disorders (WLBDs) are one of the most frequent and costly musculoskeletal conditions. It has been showed that WLBDs may occur when intervertebral or torso equilibrium is altered by a biomechanical perturbations or neuromuscular control error. The capacity to react to such disturbances is heavily determined by the spinal stability, provided by active and passive tissues and controlled by the central nervous system. RESEARCH QUESTION This study aims to investigate trunk stability through the Lyapunov's maximum exponent during repetitive liftings in relation to risk level, as well as to evaluate its ability to discriminate these risk levels. METHODS Fifteen healthy volunteers performed fatiguing lifting tasks at three different frequencies corresponding to low, medium, and high risk levels according to the National Institute for Occupational Safety and Health (NIOSH) equation. We investigated changes in spinal stability during fatiguing lifting tasks at different risk levels using the maximum Lyapunov's index (λMax) computed from trunk accelerations recorded by placing three IMUs at pelvis, lower and upper spine levels. A two-way repeated-measures ANOVA was performed to determine if there was any significant effect on λMax among the three risk levels and the time (start, mid, and end of the task). Additionally, we examined the Pearson's correlation of λMax with the trunk muscle co-activation, computed from trunk sEMG. RESULTS Our findings show an increase in trunk stability with increasing risk level and as the lifting task progressed over time. A negative correlation between λMax and trunk co-activation was observed which illustrates that the increase in spinal stability could be partially attributed to increased trunk muscle co-activation. SIGNIFICANCE This study highlights the possibility of generating stability measures from kinematic data as risk assessment features in fatiguing tasks which may prove useful to detect the risk of developing work-related low back pain disorders and allow the implementation of early ergonomic interventions.
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Nonlinear Analyses Distinguish Load Carriage Dynamics in Walking and Standing: A Systematic Review. J Appl Biomech 2022; 38:434-447. [PMID: 36170973 DOI: 10.1123/jab.2022-0062] [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: 03/03/2022] [Revised: 08/08/2022] [Accepted: 08/15/2022] [Indexed: 11/18/2022]
Abstract
Load carriage experiments are typically performed from a linear perspective that assumes that movement variability is equivalent to error or noise in the neuromuscular system. A complimentary, nonlinear perspective that treats variability as the object of study has generated important results in movement science outside load carriage settings. To date, no systematic review has yet been conducted to understand how load carriage dynamics change from a nonlinear perspective. The goal of this systematic review is to fill that need. Relevant literature was extracted and reviewed for general trends involving nonlinear perspectives on load carriage. Nonlinear analyses that were used in the reviewed studies included sample, multiscale, and approximate entropy; the Lyapunov exponent; fractal analysis; and relative phase. In general, nonlinear tools successfully distinguish between unloaded and loaded conditions in standing and walking, although not in a consistent manner. The Lyapunov exponent and entropy were the most used nonlinear methods. Two noteworthy findings are that entropy in quiet standing studies tends to decrease, whereas the Lyapunov exponent in walking studies tends to increase, both due to added load. Thus, nonlinear analyses reveal altered load carriage dynamics, demonstrating promise in applying a nonlinear perspective to load carriage while also underscoring the need for more research.
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Li J, Song Y, Xuan R, Sun D, Teo EC, Bíró I, Gu Y. Effect of Long-Distance Running on Inter-segment Foot Kinematics and Ground Reaction Forces: A Preliminary Study. Front Bioeng Biotechnol 2022; 10:833774. [PMID: 35309978 PMCID: PMC8931215 DOI: 10.3389/fbioe.2022.833774] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2021] [Accepted: 01/27/2022] [Indexed: 11/13/2022] Open
Abstract
Long-distance running has gained massive popularity in recent years, yet the intra-foot adaptations during this event remain unclear. This study aimed to examine the kinematic and ground reaction force alterations induced within the foot following a 5 and 10 km run using the Oxford Foot Model Ten marathon-experienced recreational runners participated in this study. Five-kilometer running led to more rearfoot dorsiflexion, rearfoot eversion, and rearfoot rotation while less forefoot plantarflexion during the stance phase. Increased rearfoot plantarflexion, while decreased forefoot plantarflexion, supination, adduction, and hallux plantarflexion were observed at 10 km. In addition, the forefoot space of footwear was found to play a role in hallux kinematics. Concerning GRFs, only a lesser propulsive force was presented after a 10 km run. Findings of this study showed that 5 km of running would induce excessive foot motion while 10 km of running may gradually change the foot posture and lead to reduced propulsive forces, which could potentially increase the risks of running-related injuries (RRI) due to overuse or fatigue. Nevertheless, further research is warranted, and this study could be used as a preliminary reference to evaluate and predict foot running-related injuries.
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Affiliation(s)
- Jialin Li
- The Affiliated Hospital of Medical School, Ningbo University, Ningbo, China
- Ningbo University School of Medicine, Ningbo University, Ningbo, China
| | - Yang Song
- Research Academy of Human Biomechanics, Ningbo University, Ningbo, China
- Doctoral School on Safety and Security Sciences, Óbuda University, Budapest, Hungary
- Faculty of Engineering, University of Szeged, Szeged, Hungary
| | - Rongrong Xuan
- The Affiliated Hospital of Medical School, Ningbo University, Ningbo, China
- Ningbo University School of Medicine, Ningbo University, Ningbo, China
- *Correspondence: Rongrong Xuan, ; Ee-Chon Teo, ; Yaodong Gu,
| | - Dong Sun
- Research Academy of Human Biomechanics, Ningbo University, Ningbo, China
| | - Ee-Chon Teo
- Research Academy of Human Biomechanics, Ningbo University, Ningbo, China
- *Correspondence: Rongrong Xuan, ; Ee-Chon Teo, ; Yaodong Gu,
| | - István Bíró
- Doctoral School on Safety and Security Sciences, Óbuda University, Budapest, Hungary
- Faculty of Engineering, University of Szeged, Szeged, Hungary
| | - Yaodong Gu
- Research Academy of Human Biomechanics, Ningbo University, Ningbo, China
- *Correspondence: Rongrong Xuan, ; Ee-Chon Teo, ; Yaodong Gu,
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Rossi MK, Pasanen K, Heinonen A, Äyrämö S, Räisänen AM, Leppänen M, Myklebust G, Vasankari T, Kannus P, Parkkari J. Performance in dynamic movement tasks and occurrence of low back pain in youth floorball and basketball players. BMC Musculoskelet Disord 2020; 21:350. [PMID: 32503505 PMCID: PMC7275454 DOI: 10.1186/s12891-020-03376-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Accepted: 05/28/2020] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND Prospective studies investigating risk factors for low back pain (LBP) in youth athletes are limited. The aim of this prospective study was to investigate the association between hip-pelvic kinematics and vertical ground reaction force (vGRF) during landing tasks and LBP in youth floorball and basketball players. METHODS Three-hundred-and-eighty-three Finnish youth female and male floorball and basketball players (mean age 15.7 ± 1.8) participated and were followed up on for 3 years. At the beginning of every study year the players were tested with a single-leg vertical drop jump (SLVDJ) and a vertical drop jump (VDJ). Hip-pelvic kinematics, measured as femur-pelvic angle (FPA) during SLVDJ landing, and peak vGRF and side-to-side asymmetry of vGRF during VDJ landing were the investigated risk factors. Individual exposure time and LBP resulting in time-loss were recorded during the follow-up. Cox's proportional hazard models with mixed effects and time-varying risk factors were used for analysis. RESULTS We found an increase in the risk for LBP in players with decreased FPA during SLVDJ landing. There was a small increase in risk for LBP with a one-degree decrease in right leg FPA during SLVDJ landing (HR 1.09, 95% CI 1.02 to 1.17, per one-degree decrease of FPA). Our results showed no significant relationship between risk for LBP and left leg FPA (HR 1.04, 95% CI 0.97 to 1.11, per one-degree decrease of FPA), vGRF (HR 1.83, 95% CI 0.95 to 3.51) or vGRF side-to-side difference (HR 1.22, 95% CI 0.65 to 2.27) during landing tasks. CONCLUSIONS Our results suggest that there is an association between hip-pelvic kinematics and future LBP. However, we did not find an association between LBP and vGRF. In the future, the association between hip-pelvic kinematics and LBP occurrence should be investigated further with cohort and intervention studies to verify the results from this investigation. LEVEL OF EVIDENCE Prognosis, level 1b.
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Affiliation(s)
- M K Rossi
- Tampere Research Center of Sports Medicine, UKK Institute, 33501, Tampere, Finland.
- Faculty of Sport and Health Sciences, University of Jyväskylä, Jyväskylä, Finland.
| | - K Pasanen
- Tampere Research Center of Sports Medicine, UKK Institute, 33501, Tampere, Finland
- Sport Injury Prevention Research Centre, Faculty of Kinesiology, University of Calgary, Calgary, Canada
- Alberta Children's Hospital Research Institute, University of Calgary, Calgary, Canada
- McCaig Institute for Bone and Joint Health, University of Calgary, Calgary, Canada
| | - A Heinonen
- Faculty of Sport and Health Sciences, University of Jyväskylä, Jyväskylä, Finland
| | - S Äyrämö
- Faculty of Information Technology, University of Jyväskylä, Jyväskylä, Finland
| | - A M Räisänen
- Sport Injury Prevention Research Centre, Faculty of Kinesiology, University of Calgary, Calgary, Canada
| | - M Leppänen
- Tampere Research Center of Sports Medicine, UKK Institute, 33501, Tampere, Finland
| | - G Myklebust
- Oslo Sports Trauma Research Center, Department of Sports Sciences, Norwegian School of Sport Sciences, Oslo, Norway
| | - T Vasankari
- Tampere Research Center of Sports Medicine, UKK Institute, 33501, Tampere, Finland
| | - P Kannus
- Tampere Research Center of Sports Medicine, UKK Institute, 33501, Tampere, Finland
- Department of Orthopedics & Traumatology, Tampere University Hospital, Tampere, Finland
| | - J Parkkari
- Tampere Research Center of Sports Medicine, UKK Institute, 33501, Tampere, Finland
- Tampere University Hospital, Tampere, Finland
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Mavor MP, Graham RB. The effects of protective footwear on spine control and lifting mechanics. APPLIED ERGONOMICS 2019; 76:122-129. [PMID: 30642517 DOI: 10.1016/j.apergo.2018.12.009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2018] [Revised: 11/17/2018] [Accepted: 12/13/2018] [Indexed: 06/09/2023]
Abstract
Manual materials handling is often performed in hazardous environments where protective footwear must be worn; however, workers can wear different types of footwear depending on the hazards present. Therefore, the goal of this study was to investigate how three-dimensional lifting mechanics and trunk local dynamic stability are affected by different types of protective footwear (i.e. steel-toed shoes (unlaced boot), steel-toed boots (work boot), and steel-toed boots with a metatarsal guard (MET)). Twelve males and twelve females performed a repetitive lifting task at 10% of their maximum lifting effort, under three randomized footwear conditions. Footwear type influenced ankle range of motion (ROM). The work boot condition reduced ankle sagittal ROM (p = 0.007) and the MET condition reduced ankle ROM in the sagittal (p = 0.004), frontal (p = 0.001) and transverse (p = 0.003) planes. Despite these differences at the ankle, no other changes in participant lifting mechanics were observed.
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Affiliation(s)
- Matthew P Mavor
- School of Human Kinetics, University of Ottawa, 75 Laurier Ave E, Ottawa, Ontario, K1N 6N5, Canada.
| | - Ryan B Graham
- School of Human Kinetics, University of Ottawa, 75 Laurier Ave E, Ottawa, Ontario, K1N 6N5, Canada.
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Sun D, Fekete G, Mei Q, Gu Y. The effect of walking speed on the foot inter-segment kinematics, ground reaction forces and lower limb joint moments. PeerJ 2018; 6:e5517. [PMID: 30155372 PMCID: PMC6109584 DOI: 10.7717/peerj.5517] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Accepted: 08/06/2018] [Indexed: 12/03/2022] Open
Abstract
Background Normative foot kinematic and kinetic data with different walking speeds will benefit rehabilitation programs and improving gait performance. The purpose of this study was to analyze foot kinematics and kinetics differences between slow walking (SW), normal walking (NW) and fast walking (FW) of healthy subjects. Methods A total of 10 healthy male subjects participated in this study; they were asked to carry out walks at a self-selected speed. After measuring and averaging the results of NW, the subjects were asked to perform a 25% slower and 25% faster walk, respectively. Temporal-spatial parameters, kinematics of the tibia (TB), hindfoot (HF), forefoot (FF) and hallux (HX), and ground reaction forces (GRFs) were recorded while the subjects walked at averaged speeds of 1.01 m/s (SW), 1.34 m/s (NW), and 1.68 m/s (FW). Results Hindfoot relative to tibia (HF/TB) and forefoot relative to hindfoot (FF/HF) dorsiflexion (DF) increased in FW, while hallux relative to forefoot (HX/FF) DF decreased. Increased peak eversion (EV) and peak external rotation (ER) in HF/TB were observed in FW with decreased peak supination (SP) in FF/HF. GRFs were increased significantly with walking speed. The peak values of the knee and ankle moments in the sagittal and frontal planes significantly increased during FW compared with SW and NW. Discussion Limited HF/TB and FF/HF motion of SW was likely compensated for increased HX/FF DF. Although small angle variation in HF/TB EV and FF/HF SP during FW may have profound effects for foot kinetics. Higher HF/TB ER contributed to the FF push-off the ground while the center of mass (COM) progresses forward in FW, therefore accompanied by higher FF/HF abduction in FW. Increased peak vertical GRF in FW may affected by decreased stance duration time, the biomechanical mechanism maybe the change in vertical COM height and increase leg stiffness. Walking speed changes accompanied with modulated sagittal plane ankle moments to alter the braking GRF during loading response. The findings of foot kinematics, GRFs, and lower limb joint moments among healthy males may set a reference to distinguish abnormal and pathological gait patterns.
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Affiliation(s)
- Dong Sun
- Faculty of Sports Science, Ningbo University, Ningbo, China.,Faculty of Engineering, University of Pannonia, Veszprem, Hungary.,Savaria Institute of Technology, Eötvös Lorand University, Szombathely, Hungary
| | - Gusztáv Fekete
- Faculty of Engineering, University of Pannonia, Veszprem, Hungary.,Savaria Institute of Technology, Eötvös Lorand University, Szombathely, Hungary
| | - Qichang Mei
- Faculty of Sports Science, Ningbo University, Ningbo, China.,Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Yaodong Gu
- Faculty of Sports Science, Ningbo University, Ningbo, China.,Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
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Svoboda Z, Janura M, Kutilek P, Janurova E. Relationships between movements of the lower limb joints and the pelvis in open and closed kinematic chains during a gait cycle. J Hum Kinet 2016; 51:37-43. [PMID: 28149366 PMCID: PMC5260548 DOI: 10.1515/hukin-2015-0168] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Lots of athletic skills performed during practice or competition are initiated by the legs, where athletes either walk or run prior to executing specific skills. Kinematic chains are used to describe the relationships between body segments and joints during movement. The aim of this study was to determine the relationships between movements of lower limb segments and the pelvis in open and closed kinematic chains while walking. The experimental group consisted of 32 males (age 23.3 ± 2.5 years, body mass 78.1 ± 8.7 kg, body height 182 ± 6 cm). For 3D analysis, an optoelectronic system Vicon MX (7 cameras, frequency 200 Hz) was used. Positioning of the segments was determined by the PlugInGait Model. Each participant executed five trials at speeds ranging from 1.38 to 1.52 m·s-1. The relationships between angle variables of the lower limbs and the pelvis in selected gait cycle phases were evaluated using STATISTICA software (version 10.0) and the Spearman correlation. The highest numbers of moderate and large correlations were found at opposite toe off, heel rise and initial contact for the sagittal and transversal planes in comparison to the frontal plane. The closed kinematic chain had a stronger impact on determining the movement pattern. The instructions or interventions focusing on closed kinematic chain alternation are more effective for changes in a movement pattern. The preferred limb initiates kinematics in the direction of propulsion, while the non-preferred limb in internal and external rotation.
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Affiliation(s)
- Zdenek Svoboda
- Faculty of Physical Culture, Palacky University Olomouc, Olomouc, Czech Republic
| | - Miroslav Janura
- Faculty of Physical Culture, Palacky University Olomouc, Olomouc, Czech Republic
| | - Patrik Kutilek
- Faculty of Biomedical Engineering, Czech Technical University in Prague, Kladno, Czech Republic
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Mavor MP, Graham RB. Exploring the relationship between local and global dynamic trunk stabilities during repetitive lifting tasks. J Biomech 2015; 48:3955-60. [DOI: 10.1016/j.jbiomech.2015.09.026] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Revised: 09/10/2015] [Accepted: 09/24/2015] [Indexed: 10/23/2022]
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Beach TAC, Frost DM, McGill SM, Callaghan JP. Physical fitness improvements and occupational low-back loading - an exercise intervention study with firefighters. ERGONOMICS 2014; 57:744-763. [PMID: 24689834 DOI: 10.1080/00140139.2014.897374] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The impact of exercise on firefighter job performance and cardiorespiratory fitness has been studied extensively, but its effect on musculoskeletal loading remains unknown. The aim of this study was to contrast the physical fitness and low-back loading outcomes of two groups of firefighters who completed different exercise programmes. Before and after 12 weeks of exercise, subjects performed a physical fitness test battery, the Functional Movement Screen™ (FMS) and simulated job tasks during which peak L4/L5 joint compression and reaction shear forces were quantified using a dynamic biomechanical model. Subjects who exercised exhibited statistically significant improvements (p < 0.05) in body composition, cardiorespiratory fitness, muscular strength, power, endurance and flexibility, but FMS scores and occupational low-back loading measures were not consistently affected. Firefighters who are physically fit are better able to perform essential job duties and avoid cardiac events, but short-term improvements in physical fitness may not necessarily translate into reduced low-back injury risk.
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Affiliation(s)
- Tyson A C Beach
- a Faculty of Kinesiology and Physical Education , University of Toronto , Toronto , Canada
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Beaudette SM, Graham RB, Brown SH. The effect of unstable loading versus unstable support conditions on spine rotational stiffness and spine stability during repetitive lifting. J Biomech 2014; 47:491-6. [DOI: 10.1016/j.jbiomech.2013.10.055] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2013] [Revised: 10/24/2013] [Accepted: 10/26/2013] [Indexed: 10/26/2022]
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Dupeyron A, Rispens SM, Demattei C, van Dieën JH. Precision of estimates of local stability of repetitive trunk movements. EUROPEAN SPINE JOURNAL : OFFICIAL PUBLICATION OF THE EUROPEAN SPINE SOCIETY, THE EUROPEAN SPINAL DEFORMITY SOCIETY, AND THE EUROPEAN SECTION OF THE CERVICAL SPINE RESEARCH SOCIETY 2013; 22:2678-85. [PMID: 23653131 DOI: 10.1007/s00586-013-2797-2] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Revised: 03/09/2013] [Accepted: 04/25/2013] [Indexed: 11/29/2022]
Abstract
PURPOSE Local dynamic stability of trunk movements quantified by means of the maximum Lyapunov exponent (λmax) can provide information on trunk motor control and might offer a measure of trunk control in low-back pain patients. It is unknown how many repetitions are necessary to obtain sufficiently precise estimates of λmax and whether fatigue effects on λmax can be avoided while increasing the number of repetitions. METHOD Ten healthy subjects performed 100 repetitions of trunk movements in flexion, of trunk rotation and of a task combining these movement directions. λmax was calculated from thorax, pelvis and trunk (thorax relative to pelvis) kinematics. Data series were analyzed using a bootstrap procedure; ICC and coefficient of variation were used to quantify precision as a function of the number of cycles analyzed. ANOVA was used to compare movement tasks and to test for effects of time. RESULTS Trunk local stability reached acceptable precision level after 30 repetitions. λmax was higher (indicating lower stability) in flexion, compared to rotation and combined tasks. There was no time effect (fatigue). λmax of trunk movement was lower and less variable than that of thorax and pelvis movements. CONCLUSIONS The data provided allow for an informed choice of the number of repetitions in assessing local dynamic stability of trunk movements, weighting the gain in precision against the increase in measurement effort. Within the 100 repetitions tested, fatigue did not affect results. We suggest that increased stability during asymmetric movement may be explained by higher co-activation of trunk muscles.
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Affiliation(s)
- Arnaud Dupeyron
- Movement to Health Laboratory, Euromov, Montpellier 1 University, 700 Av Pic Saint Loup, 34090, Montpellier, France,
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Lee J, Nussbaum MA. Experienced workers may sacrifice peak torso kinematics/kinetics for enhanced balance/stability during repetitive lifting. J Biomech 2013; 46:1211-5. [DOI: 10.1016/j.jbiomech.2013.01.011] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2012] [Revised: 01/16/2013] [Accepted: 01/17/2013] [Indexed: 11/26/2022]
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