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1.
Appl Ergon ; 98: 103589, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34563748

RESUMO

Whole-body powered exoskeletons (WB-PEXOs) can be effective in reducing the physical demands of heavy occupational work, yet almost no empirical evidence exists on the effects of WB-PEXO use. This study assessed the effects of WB-PEXO use on back and leg muscle activities during lab-based simulations of load handling tasks. Six participants (4M, 2F) completed two such tasks (load carriage and stationary load transfer), both with and without a WB-PEXO, and with a range of load masses in each task. WB-PEXO use reduced median levels of muscle activity in the back (∼42-53% in thoracic and ∼24-43% in lumbar regions) and legs (∼41-63% in knee flexors and extensors), and mainly when handling loads beyond low-moderate levels (10-15 kg). Overall, using the WB-PEXO also reduced inter-individual variance (smaller SD) in muscle activities. Future work should examine diverse users, focus on finding effective matches between WB-PEXO use and specific tasks, and identify applications in varied work environments.


Assuntos
Exoesqueleto Energizado , Humanos , Perna (Membro) , Região Lombossacral , Músculo Esquelético , Projetos Piloto
2.
Ergonomics ; : 1-13, 2021 Oct 25.
Artigo em Inglês | MEDLINE | ID: mdl-34663181

RESUMO

The effect on muscle activity variation of combining different office tasks is not known. We recorded electromyography from the upper trapezius (UT), wrist extensor (WE) and lumbar erector spinae (LES) in 24 office workers during five productive tasks, and breaks. Minute-to-minute variance was then estimated, by simulations, in a reference 'job' consisting of 85% sitting computer work and 15% breaks, and in 'jobs' where sitting computer work was replaced by different proportions of the other office tasks and breaks. Replacing sitting computer work with sitting non-computer work increased estimated variance by, in median, 23% (UT), 19% (WE) and 0% (LES). Replacing it with other tasks, in particular, standing computer and non-computer work, was less effective in increasing variance. Thus, some combinations of office tasks have a slight potential to increase muscle activity variation in the shoulder and lower arm, but not the lumbar back, while others will be ineffective. Practitioner summary: The need for exposure variation is often emphasised in office ergonomics. We estimated the effect on muscle activity in the shoulder, forearm and lumbar back of combining sitting computer work with other available tasks and breaks, finding that introduction of sitting non-computer tasks and non-desk work slightly increased variation; other tasks were essentially non-effective.

3.
J Biomech ; 123: 110501, 2021 06 23.
Artigo em Inglês | MEDLINE | ID: mdl-34000644

RESUMO

Back-support exoskeletons (BSEs) are a promising ergonomic intervention to mitigate the risk of occupational low back pain. Although growing evidence points to the beneficial effects of BSEs, specifically in reducing low-back physical demands, there is limited understanding of potential unintended consequences of BSE use on neuromuscular control of the trunk during manual material handling (MMH). We quantified the effects of two passive BSEs (BackX™ AC and Laevo™ V2.5) on trunk dynamic stability and movement coordination during a repetitive lifting task. Eighteen participants (gender-balanced) completed four minutes of repetitive lifting in nine different conditions, involving symmetric and asymmetric postures when using the BSEs (along with no BSE as a control condition). Maximum Lyapunov exponents (short-term: λmax-s; long-term: λmax-l) and Floquet multipliers (FMmax) were respectively calculated to quantify the local dynamic and orbital stability of thorax and pelvis trajectories. Thorax-pelvis segmental coordination was also quantified using the continuous relative phase. Wearing the Laevo™ significantly increased λmax-s for the pelvis (by ~ 8%) and FMmax for the thorax and pelvis (by ~ 5-10%). Use of either BSE decreased the in-phase coordination pattern for the thorax-pelvis coupling (by ~ 15%). These results suggest that BSE use can compromise neuromuscular control of the trunk, and caution should thus be used in selecting a suitable BSE for use in a given MMH task. Future work is needed, however, to assess the generalizability of different BSE design approaches in terms of unintended short-term and long-term effects on trunk neuromuscular control.


Assuntos
Exoesqueleto Energizado , Fenômenos Biomecânicos , Humanos , Remoção , Análise de Sistemas , Tronco
4.
Phys Ther Sport ; 49: 112-121, 2021 May.
Artigo em Inglês | MEDLINE | ID: mdl-33667776

RESUMO

OBJECTIVES: We aimed to assess the test-retest reliability of a supine and standing knee joint position sense (JPS) test, respectively, and whether they discriminate knees with anterior cruciate ligament (ACL) injury from asymptomatic knees. DESIGN: Repeated measures and cross-sectional. SETTING: Research laboratory. PARTICIPANTS: For test-retest reliability, 24 persons with asymptomatic knees. For discriminative analysis: 1) ACLR - 18 persons on average 23 months after unilateral ACL reconstruction, 2) CTRL - 23 less-active persons, and 3) ATHL - 21 activity level-matched athletes. MAIN OUTCOME MEASURES: Absolute error (AE) and variable error (VE). RESULTS: Test-retest reliability was generally highest for AE of the standing test (ICC 0.64-0.91). Errors were less for the standing compared to the supine test across groups. CTRL had greater knee JPS AE (P = 0.005) and VE (P = 0.040) than ACLR. ACLR knees showed greater VE compared to the contralateral non-injured knees for both tests (P = 0.032), albeit with a small effect size (ηp2 = 0.244). CONCLUSIONS: Our standing test was more reliable and elicited lesser errors than our supine test. Less-active controls, rather than ACLR, produced significantly greater errors. Activity level may be a more predominant factor than ACLR for knee JPS ∼2 years post-reconstruction.


Assuntos
Articulação do Joelho , Propriocepção , Posição Ortostática , Decúbito Dorsal , Adulto , Lesões do Ligamento Cruzado Anterior/cirurgia , Reconstrução do Ligamento Cruzado Anterior , Estudos Transversais , Feminino , Humanos , Masculino , Amplitude de Movimento Articular , Reprodutibilidade dos Testes , Adulto Jovem
5.
Ergonomics ; 64(8): 983-994, 2021 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-33565921

RESUMO

Sit-stand desks continue to be a popular intervention for office work. While previous studies have reported changes in subjective measures, there is limited understanding of how sit-stand work differs from prolonged sitting or standing work, from a biomechanical standpoint. The objective of this study was to investigate the effects of prolonged sitting, prolonged standing, and a sit-stand paradigm on changes in trunk stiffness, low back discomfort, and trunk muscle activation. Twelve healthy participants performed 2 h of computer-based tasks in each protocol, on three different days. The sit-stand protocol was associated with a significant increase in trunk stiffness and a decrease in muscle activation of lumbar multifidus and longissimus thoracis pars thoracis, compared to both prolonged sitting and standing. Both sitting and standing were associated with increased low back discomfort. These findings may be worth exploring in more detail, for why alternating sit-stand patterns may help alleviate low back pain. Practitioner summary: We explored changes in objective and subjective measures related to low back discomfort following prolonged sitting, standing, and alternating sit-stand patterns. Alternating sit-stand pattern was associated with increased trunk stiffness and decreased back muscle activity. Hence, sit-stand desks may have benefits in terms of preventing/mitigating low back pain. Abbreviations: DOF: degree of freedom; EMG: electromyogram; ILL: iliocostalis lumborum pars lumborum; LTL: longissimus thoracis pars lumborum; LTT: longissimus thoracis pars thoracis; LBP: low back pain; LM: lumbar multifidus; MVEs: maximum isometric voluntary exertions; RANOVA: repeated-measure analysis of variance; RMS: root mean square.


Assuntos
Músculos do Dorso , Dor Lombar , Humanos , Dor Lombar/etiologia , Postura Sentada , Posição Ortostática , Tronco
6.
J Electromyogr Kinesiol ; 57: 102516, 2021 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-33493784

RESUMO

While occupational back-support exoskeletons (BSEs) are considered as potential workplace interventions, BSE use may compromise postural control. Thus, we investigated the effects of passive BSEs on postural balance during quiet upright stance and functional limits of stability. Twenty healthy adults completed trials of quiet upright stance with differing levels of difficulty (bipedal and unipedal stance; each with eyes open and closed), and executed maximal voluntary leans. Trials were done while wearing two different BSEs (SuitX™, Laevo™) and in a control (no-BSE) condition. BSE use significantly increased center-of-pressure (COP) median frequency and mean velocity during bipedal stance. In unipedal stance, using the Laevo™ was associated with a significant improvement in postural balance, especially among males, as indicated by smaller COP displacement and sway area, and a longer time to contact the stability boundary. BSE use may affect postural balance, through translation of the human + BSE center-of-mass, restricted motion, and added supportive torques. Furthermore, larger effects of BSEs on postural balance were evident among males. Future work should further investigate the gender-specificity of BSE effects on postural balance and consider the effects of BSEs on dynamic stability.


Assuntos
Músculos do Dorso/fisiologia , Exoesqueleto Energizado , Equilíbrio Postural/fisiologia , Posição Ortostática , Adulto , Exoesqueleto Energizado/tendências , Feminino , Humanos , Masculino , Adulto Jovem
7.
Appl Ergon ; 91: 103307, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33202332

RESUMO

Twenty participants (18 males and 2 females) completed postural stability assessments before and after 4-h exposure to whole body vibration (WBV) in four experimental conditions: (a) vertical-dominant WBV with vertical passive air suspension, (b) multi-axial WBV with vertical passive air suspension, (c) multi-axial WBV with multi-axial active suspension, and (d) no WBV condition. Center of pressure (COP)-based postural sway measures significantly increased following multi-axial WBV exposure. Increase in COP velocity and displacement following multi-axial WBV was significantly higher than the increase in all the other exposure conditions. However, no significant differences between the WBV conditions were observed in functional limits of stability and anticipatory postural adjustments. While our results show standing balance to be impaired following the multi-axial WBV exposure of off-road mining vehicles, dynamic stability across a broader range of conditions needs to be understood to causally link postural stability decrements to increased fall-risks associated with off-road vehicle operators.


Assuntos
Exposição Ocupacional , Equilíbrio Postural , Vibração , Feminino , Humanos , Masculino , Mineração , Veículos Automotores
8.
Sci Rep ; 10(1): 16699, 2020 10 07.
Artigo em Inglês | MEDLINE | ID: mdl-33028829

RESUMO

Self-injurious behavior (SIB) is among the most dangerous concerns in autism spectrum disorder (ASD), often requiring detailed and tedious management methods. Sensor-based behavioral monitoring could address the limitations of these methods, though the complex problem of classifying variable behavior should be addressed first. We aimed to address this need by developing a group-level model accounting for individual variability and potential nonlinear trends in SIB, as a secondary analysis of existing data. Ten participants with ASD and SIB engaged in free play while wearing accelerometers. Movement data were collected from > 200 episodes and 18 different types of SIB. Frequency domain and linear movement variability measures of acceleration signals were extracted to capture differences in behaviors, and metrics of nonlinear movement variability were used to quantify the complexity of SIB. The multi-level logistic regression model, comprising of 12 principal components, explained > 65% of the variance, and classified SIB with > 75% accuracy. Our findings imply that frequency-domain and movement variability metrics can effectively predict SIB. Our modeling approach yielded superior accuracy than commonly used classifiers (~ 75 vs. ~ 64% accuracy) and had superior performance compared to prior reports (~ 75 vs. ~ 69% accuracy) This work provides an approach to generating an accurate and interpretable group-level model for SIB identification, and further supports the feasibility of developing a real-time SIB monitoring system.


Assuntos
Transtorno do Espectro Autista/psicologia , Comportamento Autodestrutivo/classificação , Acelerometria , Adolescente , Criança , Pré-Escolar , Feminino , Humanos , Masculino , Modelos Psicológicos , Movimento , Comportamento Autodestrutivo/psicologia
9.
Am J Ind Med ; 63(11): 1017-1028, 2020 11.
Artigo em Inglês | MEDLINE | ID: mdl-32926450

RESUMO

BACKGROUND: As the sustainability of the agricultural workforce has been threatened by the high prevalence of back pain, developing effective interventions to reduce its burden within farming will contribute to the long-term health and productivity of workers. Passive back-support exoskeletons are being explored as an intervention to reduce the physical demands on the back muscles, and consequently mitigate the risk of back pain, in many industrial sectors. METHODS: This study investigated whether exoskeleton use could reduce farmers' low back muscle load. Electromyography was used to evaluate exoskeleton use in field and laboratory settings. A total of 14 farmers (13 males and 1 female) with a mean age of 49 (SD = 12) years and 6 female nonfarmers (mean age 28, SD = 5 years) performed a standardized set of tasks that included symmetric and asymmetric lifting and sustained trunk flexion. Following the standardized tasks, 14 farmers also performed regular, real-world, farm tasks with and without use of the exoskeleton at their farms. RESULTS: Exoskeleton use decreased back muscular load during farming activities up to 65%, 56%, and 48% in static, median, and peak muscle activity, respectively. This indicates potential benefits of exoskeleton use to help farmers work under less muscular load. Paradoxically, exoskeleton use during standardized tasks increased muscle activity for some participants. CONCLUSIONS: This study demonstrates the potential effects of using passive exoskeletons in agriculture through observational and experimental research, and is among the first that explores the potential for using exoskeletons during actual work tasks in farm settings.


Assuntos
Doenças dos Trabalhadores Agrícolas/prevenção & controle , Exoesqueleto Energizado , Dor Lombar/prevenção & controle , Adulto , Doenças dos Trabalhadores Agrícolas/etiologia , Músculos do Dorso/fisiologia , Fenômenos Biomecânicos , Feminino , Humanos , Remoção/efeitos adversos , Dor Lombar/etiologia , Masculino , Pessoa de Meia-Idade , Análise e Desempenho de Tarefas , Suporte de Carga/fisiologia
10.
Appl Ergon ; 89: 103194, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32854824

RESUMO

Back-support exoskeletons (BSEs) are wearable systems designed to reduce physical demands on the back, but which could have undesired effects beyond this design intention. Participants (n = 18) used two commercial BSEs to complete a brief (~15-20 s) simulated manual assembly task in varying conditions, with outcome measures that included: working posture, activity levels in "secondary" muscle groups (shoulders and thighs), perceived balance, discomfort, and usability. Using a BSE led to small and inconsistent changes in working postures (e.g., < ~14° change in lumbar flexion), muscular activity in the secondary muscle groups (<±2% of maximum voluntary isometric contractions), or perceived balance. Limitations in movement were reported for both BSEs, however, along with moderate levels of discomfort. Task-specific responses were evident for all outcome measures, though these depended on the specific BSE used and differed between genders in many cases. Future work should focus on interactions between a given user, BSE design, and task conditions.


Assuntos
Desenho de Equipamento , Exoesqueleto Energizado/efeitos adversos , Limitação da Mobilidade , Exposição Ocupacional/análise , Trabalho/fisiologia , Acelerometria/instrumentação , Acelerometria/métodos , Adulto , Dor nas Costas/etiologia , Dor nas Costas/prevenção & controle , Fenômenos Biomecânicos , Simulação por Computador , Feminino , Humanos , Masculino , Sistemas Homem-Máquina , Movimento , Músculo Esquelético/fisiologia , Doenças Profissionais/etiologia , Doenças Profissionais/prevenção & controle , Exposição Ocupacional/efeitos adversos , Exposição Ocupacional/prevenção & controle , Equilíbrio Postural/fisiologia , Postura/fisiologia , Ombro/fisiologia , Análise e Desempenho de Tarefas , Coxa da Perna/fisiologia , Suporte de Carga/fisiologia , Adulto Jovem
11.
Appl Ergon ; 88: 103156, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32678776

RESUMO

Two passive back-support exoskeleton (BSE) designs were assessed in terms of muscular activity, energy expenditure, joint kinematics, and subjective responses. Eighteen participants (gender-balanced) completed repetitive lifting tasks in nine different conditions, involving symmetric and asymmetric postures and using two BSEs (along with no BSE as a control condition). Wearing both BSEs significantly reduced peak levels of trunk extensor muscle activity (by ~9-20%) and reduced energy expenditure (by ~8-14%). Such reductions, though, were more pronounced in the symmetric conditions and differed between the two BSEs tested. Participants reported lower perceived exertion using either BSE yet raised concerns regarding localized discomfort. Minimal changes in lifting behaviors were evident when using either BSE, and use of both BSEs led to generally positive usability ratings. While these results are promising regarding the occupational use of BSEs, future work is recommended to consider inter-individual differences to accommodate diverse user needs and preferences.


Assuntos
Músculos do Dorso/fisiologia , Ergonomia , Exoesqueleto Energizado , Remoção , Análise e Desempenho de Tarefas , Adulto , Fenômenos Biomecânicos , Calorimetria Indireta , Eletromiografia , Metabolismo Energético/fisiologia , Feminino , Humanos , Masculino , Músculo Esquelético/fisiologia , Esforço Físico/fisiologia , Postura/fisiologia , Tronco/fisiologia
12.
Appl Ergon ; 85: 103046, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32174342

RESUMO

Research suggests an association between motor variability (MV) during repetitive work and work-related musculoskeletal disorders (MSDs). However, whether MV is a consistent individual trait, even across working conditions or tasks, remains unknown. This study assessed whether individual MV traits were consistent during complex work performed under different temporal conditions. Fifteen women performed cyclic assembly under four conditions differing in pace and organisation (line-type, batch-type). MV of trapezius muscle activity and upper arm elevation was quantified and partitioned into variance components. For all MV metrics, a non-zero between-subjects variance was found, indicating consistent individual MV traits across conditions. Variance between subjects was higher for electromyography (EMG) MV metrics compared with kinematic metrics. Our results showed individuals exhibited consistent MV traits across working conditions differing in pace and production process. Further research is needed to understand whether MV is an individual predictive factor for MSD onset or progression.


Assuntos
Ergonomia , Movimento/fisiologia , Análise e Desempenho de Tarefas , Fatores de Tempo , Trabalho/fisiologia , Adolescente , Adulto , Fenômenos Biomecânicos , Transtornos Traumáticos Cumulativos , Eletromiografia , Feminino , Humanos , Individualidade , Pessoa de Meia-Idade , Contração Muscular/fisiologia , Doenças Musculoesqueléticas/etiologia , Doenças Musculoesqueléticas/fisiopatologia , Doenças Profissionais/etiologia , Doenças Profissionais/fisiopatologia , Ombro/fisiologia , Músculos Superficiais do Dorso/fisiologia , Adulto Jovem
13.
Hum Factors ; 62(3): 458-474, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32017609

RESUMO

OBJECTIVE: The aim of this study was to explore the efficacy of two different passive back-support exoskeleton (BSE) designs during repetitive lifting in different postures. BACKGROUND: Although BSEs have been proposed as a potential intervention for reducing physical demands, limited information is available about the impacts of different exoskeleton designs in diverse work scenarios. METHOD: Eighteen participants (gender-balanced) performed lab-based simulations of repetitive lifting tasks. These tasks were performed in 12 different conditions, involving two BSEs and a control condition, two levels of lifting symmetry (symmetric and asymmetric), and two postures (standing and kneeling). Outcome measures described muscle activity and energy expenditure, along with perceived discomfort, balance, and usability. RESULTS: Using both BSEs significantly reduced peak activity of the trunk extensor muscles (by ~10%-28%) and energy expenditure (by ~4%-13%) in all conditions tested. Such reductions, though, were task dependent and differed between the two BSEs. In most of the tested conditions, using BSEs positively affected subjective responses regarding perceived exertion and usability. CONCLUSION: Our results suggest that the beneficial effects of a BSE are task specific and depend on the specific BSE design approach. More work is needed, though, to better characterize this task specificity and to determine the generalizability of BSE effects on objective and subjective outcomes for a wider range of conditions and users. APPLICATION: Our results provide new evidence to guide the selection and application of passive BSE designs in diverse lifting tasks.


Assuntos
Metabolismo Energético , Exoesqueleto Energizado , Músculo Esquelético/fisiologia , Postura/fisiologia , Design Centrado no Usuário , Suporte de Carga/fisiologia , Adulto , Dorso/fisiologia , Feminino , Humanos , Masculino , Percepção/fisiologia , Esforço Físico/fisiologia , Análise e Desempenho de Tarefas , Dispositivos Eletrônicos Vestíveis , Adulto Jovem
14.
Hum Factors ; 62(3): 441-457, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-31934773

RESUMO

OBJECTIVE: To assess the efficacy of two different passive back-support exoskeleton (BSE) designs, in terms of trunk muscle activity, perceived low-back exertion, and task performance. BACKGROUND: BSEs have the potential to be an effective intervention for reducing low-back physical demands, yet little is known about the impacts of different designs in work scenarios requiring varying degrees of symmetric and asymmetric trunk bending during manual assembly tasks. METHOD: Eighteen participants (gender balanced) completed lab-based simulations of a precision manual assembly task using a "grooved pegboard." This was done in 26 different conditions (20 unsupported; 6 supported, via a chair), which differed in vertical height, horizontal distance, and orientation. RESULTS: Using both BSEs reduced metrics of trunk muscle activity in many task conditions (≤47% reductions when using BackX™ and ≤24% reductions when using Laevo™). Such reductions, though, were more pronounced in the conditions closer to the mid-sagittal plane and differed between the two BSEs tested. Minimal effects on task completion times or ratings of perceived exertion were found for both BSEs. CONCLUSION: Our findings suggest that using passive BSEs can be beneficial for quasi-static manual assembly tasks, yet their beneficial effects can be task specific and specific to BSE design approaches. Further work is needed, though, to better characterize this task specificity and to assess the generalizability of different BSE design approaches in terms of physical demands, perceived exertion, and task performance. APPLICATION: These results can help guide the choice and application of passive BSE designs for diverse work scenarios involving nonneutral trunk postures.


Assuntos
Exoesqueleto Energizado , Dor Lombar/prevenção & controle , Músculo Esquelético/fisiologia , Percepção/fisiologia , Esforço Físico , Análise e Desempenho de Tarefas , Tronco/fisiologia , Design Centrado no Usuário , Adulto , Fenômenos Biomecânicos , Feminino , Humanos , Dor Lombar/fisiopatologia , Masculino , Doenças Profissionais/fisiopatologia , Doenças Profissionais/prevenção & controle , Postura/fisiologia , Dispositivos Eletrônicos Vestíveis , Adulto Jovem
15.
BMC Musculoskelet Disord ; 20(1): 476, 2019 Oct 25.
Artigo em Inglês | MEDLINE | ID: mdl-31653212

RESUMO

BACKGROUND: Research indicates reduced knee function and stability decades after anterior cruciate ligament (ACL) injury. Assessment requires reliable functional tests that discriminate such outcomes from asymptomatic knees, while providing suitable loading for different populations. The One-leg rise (OLR) test is common in clinics and research but lacks scientific evidence for its implementation. Our cross-sectional study compared performance including knee kinematics of the OLR between ACL-injured persons in the very long term to controls and between legs within these groups, and assessed the within-session reliability of the kinematics. METHODS: Seventy ACL-injured individuals (mean age 46.9 ± 5.4 years) treated with either reconstructive surgery and physiotherapy (ACLR; n = 33) or physiotherapy alone (ACLPT; n = 37), on average 23 years post-injury, and 33 age- and sex-matched controls (CTRL) attempted the OLR. Participants completed as many repetitions as possible to a maximum of 50 while recorded by motion capture. We compared between all groups and between legs within groups for total repetitions and decomposed the OLR into movement phases to compare phase completion times, maximum and range of knee abduction and adduction angles, and mediolateral knee control in up to 10 repetitions per participant. RESULTS: ACLPT performed significantly fewer OLR repetitions with their injured leg compared to the CTRL non-dominant leg (medians 15 and 32, respectively) and showed significantly greater knee abduction than ACLR and CTRL (average 2.56°-3.69° depending on phase and leg). Distribution of repetitions differed between groups, revealing 59% of ACLPT unable to complete more than 20 repetitions on their injured leg compared to 33% ACLR and 36% CTRL for their injured and non-dominant leg, respectively. Within-session reliability of all kinematic variables for all groups and legs was high (ICC 3,10 0.97-1.00, 95% CI 0.95-1.00, SEM 0.93-1.95°). CONCLUSIONS: Negative outcomes of OLR performance, particularly among ACLPT, confirm the need to address aberrant knee function and stability even decades post-ACL injury. Knee kinematics derived from the OLR were reliable for asymptomatic and ACL-injured knees. Development of the OLR protocol and analysis methods may improve its discriminative ability in identifying reduced knee function and stability among a range of clinical populations.


Assuntos
Lesões do Ligamento Cruzado Anterior/cirurgia , Reconstrução do Ligamento Cruzado Anterior , Avaliação da Deficiência , Instabilidade Articular/diagnóstico , Articulação do Joelho/fisiopatologia , Adulto , Lesões do Ligamento Cruzado Anterior/complicações , Lesões do Ligamento Cruzado Anterior/fisiopatologia , Fenômenos Biomecânicos , Estudos Transversais , Estudos de Viabilidade , Feminino , Seguimentos , Humanos , Instabilidade Articular/etiologia , Instabilidade Articular/cirurgia , Perna (Membro) , Masculino , Pessoa de Meia-Idade , Amplitude de Movimento Articular , Reprodutibilidade dos Testes , Fatores de Tempo , Resultado do Tratamento
16.
J Agric Food Chem ; 67(44): 12264-12272, 2019 Nov 06.
Artigo em Inglês | MEDLINE | ID: mdl-31613615

RESUMO

While silica particles are used extensively in food products, different grades and temperature variants of silica particles have not been compared for their physiochemical and biological properties. Different grades of silica (food-grade nanoparticles (FG-NPs), nonfood-grade nanoparticles (NFG-NPs), and food-grade micron particles (FG-MPs)) and the temperature variants generated by exposing FG-NPs to wet heating, dry heating, and refrigeration were compared for their physicochemical properties and interaction with trypsin. FG-NPs were similar to NFG-NPs and FG-MPs in their elemental composition and amorphous nature but had relatively less branched and ring siloxane groups than the latter ones. There were subtle but noticeable changes in the agglomeration behavior and relative abundance of different silica groups in FG-NPs exposed to food-handling temperatures. Secondary structure and function of trypsin were negatively impacted by FG-NPs and their temperature variants. Silica particles showed a "mixed-type inhibition" of trypsin resulting in partial digestion of bovine serum albumin. In conclusion, our studies showed differences in the surface chemistry of different grades of silica particles and temperature variants of FG-NPs and their negative impact on the structure and function of trypsin.


Assuntos
Aditivos Alimentares/química , Nanopartículas/química , Dióxido de Silício/química , Tripsina/química , Animais , Biocatálise , Bovinos , Hidrodinâmica , Tamanho da Partícula , Soroalbumina Bovina/química , Propriedades de Superfície , Temperatura
17.
Appl Ergon ; 81: 102908, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31422258

RESUMO

This study aimed at determining the extent to which individuals with neck-shoulder pain and non-symptomatic individuals differ in muscle activation patterns, when performing computer work, as quantified by exposure variation analysis (EVA). As a secondary aim, we also aimed to quantify the day-to-day reliability of EVA variables describing trapezius muscle activation in a non-symptomatic control group. Thirteen touch-typing computer users (pain: n = 5, non-symptomatic: n = 8) completed three pre-selected computer tasks in the laboratory. Upper trapezius muscle activity was recorded using electromyography and analyzed using EVA with five amplitude and five duration categories. Individuals with neck-shoulder pain spent less time at low amplitudes and exhibited longer uninterrupted periods of muscle activation compared to their non-symptomatic counterparts. Thus, non-symptomatic workers tended to switch between exposure levels more often than individuals with pain. For a majority of EVA variables, ICCs ranged from 0.6 to 0.9, and between-days coefficients of variation were between 0.4 and 2.2.


Assuntos
Terminais de Computador , Cervicalgia/fisiopatologia , Doenças Profissionais/fisiopatologia , Exposição Ocupacional/análise , Dor de Ombro/fisiopatologia , Adulto , Estudos de Casos e Controles , Feminino , Humanos , Masculino , Cervicalgia/etiologia , Doenças Profissionais/etiologia , Medição da Dor , Dor de Ombro/etiologia , Músculos Superficiais do Dorso/fisiopatologia , Análise e Desempenho de Tarefas , Trabalho/fisiologia
18.
J Nutr Biochem ; 71: 132-143, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31349120

RESUMO

Consumption of unhealthy, energy-dense palatable food during early age leads to obesity in children and the onset of obesity during childhood has a profound effect on the reproductive health of women. In this study, the mechanism underlying diet-induced obesity on ovarian dysfunction was studied by exposing rats to cafeteria diet (CAFD) for two different durations. For that purpose, 21-day-old female Sprague Dawley rats were fed ad libitum with a standard diet (control group) and a cafeteria diet (CAFD group) for a period of 20 weeks (20 W) and 32 weeks (32 W). We observed obesity, hyperglycemia, hyperlipidemia, hyperleptinemia and hypoadiponectinemia in CAFD fed groups. Hyperinsulinemia, hypergonadotrophism, hypertestosteronemia and hyperprogesteronemia were observed in the 20 W-CAFD group. Conversely, in the 32 W-CAFD group hypersecretion declined to hyposecretion. The levels of estradiol remained low during both time periods. The duration of estrous cycle was extended in the CAFD fed rats. The ovary weight was higher in the 20 W-CAFD fed rats but it was drastically reduced over a longer duration cafeteria diet feeding. In the 20 W-CAFD fed rats, the protein levels of LHR, StAR, CYP11A1, 3ß-HSD and 17ß-HSD were increased but FSHR and CYP19A1 levels were decreased in the ovary. On the other hand, gonadotropin receptor and the protein levels of steroidogenic enzymes were decreased in the ovary of 32 W-CAFD fed rats. We conclude that the duration of energy-dense diet consumption has differential regulatory mechanism in altering the ovarian steroid production. In 20 W-CAFD fed rats, hypergonadotropic condition was observed whereas, 32 W-CAFD consumption induced hypogonadotropic hypogonadism.


Assuntos
Dieta/efeitos adversos , Obesidade/etiologia , Doenças Ovarianas/metabolismo , Doenças Ovarianas/fisiopatologia , Ração Animal , Animais , Ciclo Estral/fisiologia , Feminino , Gonadotropinas/sangue , Lipídeos/sangue , Obesidade/metabolismo , Obesidade/fisiopatologia , Tamanho do Órgão , Obesidade Pediátrica , Ratos Sprague-Dawley , Receptores da Gonadotropina/metabolismo , Esteroides/metabolismo , Fatores de Tempo
19.
Ann Work Expo Health ; 63(5): 583-591, 2019 05 21.
Artigo em Inglês | MEDLINE | ID: mdl-31008506

RESUMO

INTRODUCTION: Sit-stand workstations are a popular intervention to reduce sedentary behavior (SB) in office settings. However, the extent and distribution of SB in office workers long-term accustomed to using sit-stand workstations as a natural part of their work environment are largely unknown. In the present study, we aimed to describe patterns of SB in office workers with long-term access to sit-stand workstations and to determine the extent to which these patterns vary between days and workers. METHODS: SB was objectively monitored using thigh-worn accelerometers for a full week in 24 office workers who had been equipped with a sit-stand workstation for at least 10 months. A comprehensive set of variables describing SB was calculated for each workday and worker, and distributions of these variables between days and workers were examined. RESULTS: On average, workers spent 68% work time sitting [standard deviation (SD) between workers and between days (within worker): 10.4 and 18.2%]; workers changed from sitting to standing/walking 3.2 times per hour (SDs 0.6 and 1.2 h-1); with bouts of sitting being 14.9 min long (SDs 4.2 and 8.5 min). About one-third of the workers spent >75% of their workday sitting. Between-workers variability was significantly different from zero only for percent work time sitting, while between-days (within-worker) variability was substantial for all SB variables. CONCLUSIONS: Office workers accustomed to using sit-stand workstations showed homogeneous patterns of SB when averaged across several days, except for percent work time seated. However, SB differed substantially between days for any individual worker. The finding that many workers were extensively sedentary suggests that just access to sit-stand workstations may not be a sufficient remedy against SB; additional personalized interventions reinforcing use may be needed. To this end, differences in SB between days should be acknowledged as a potentially valuable source of variation.


Assuntos
Promoção da Saúde/métodos , Saúde do Trabalhador/estatística & dados numéricos , Comportamento Sedentário , Local de Trabalho/estatística & dados numéricos , Acelerometria , Adulto , Feminino , Comportamentos Relacionados com a Saúde , Humanos , Masculino , Pessoa de Meia-Idade
20.
Ann Biomed Eng ; 47(5): 1191-1202, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30825029

RESUMO

This study aimed to determine whether inter-individual differences in learning rate of a novel motor task could be predicted by movement variability exhibited in a related baseline task, and determine which variability measures best discriminate individual differences in learning rate. Thirty-two participants were asked to repeatedly complete an obstacle course until achieving success in a dual-task paradigm. Their baseline gait kinematics during self-paced level walking were used to calculate stride-to-stride variability in stride characteristics, joint angle trajectories, and inter-joint coordination. The gait variability measures were reduced to functional attributes through principal component analysis and used as predictors in multiple linear regression models. The models were used to predict the number of trials needed by each individual to complete the obstacle course successfully. Frontal plane coordination variability of the hip-knee and knee-ankle joint couples in both stance and swing phases of baseline gait were the strongest predictors, and explained 62% of the variance in learning rate. These results show that gait variability measures can be used to predict short-term differences in function between individuals. Future research examining statistical persistence in gait time series that can capture the temporal dimension of gait pattern variability, may further improve learning performance prediction.


Assuntos
Articulação do Tornozelo/fisiologia , Marcha/fisiologia , Articulação do Quadril/fisiologia , Individualidade , Articulação do Joelho/fisiologia , Caminhada/fisiologia , Adulto , Fenômenos Biomecânicos , Feminino , Humanos , Masculino
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