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1.
Nat Commun ; 11(1): 5615, 2020 11 05.
Artigo em Inglês | MEDLINE | ID: mdl-33154381

RESUMO

Limb motion capture is essential in human motion-recognition, motor-function assessment and dexterous human-robot interaction for assistive robots. Due to highly dynamic nature of limb activities, conventional inertial methods of limb motion capture suffer from serious drift and instability problems. Here, a motion capture method with integral-free velocity detection is proposed and a wearable device is developed by incorporating micro tri-axis flow sensors with micro tri-axis inertial sensors. The device allows accurate measurement of three-dimensional motion velocity, acceleration, and attitude angle of human limbs in daily activities, strenuous, and prolonged exercises. Additionally, we verify an intra-limb coordination relationship exists between thigh and shank in human walking and running, and establish a neural network model for it. Using the intra-limb coordination model, dynamic motion capture of human lower limbs including thigh and shank is tactfully implemented by a single shank-worn device, which simplifies the capture device and reduces cost. Experiments in strenuous activities and long-time running validate excellent performance and robustness of the wearable device in dynamic motion recognition and reconstruction of human limbs.


Assuntos
Extremidades/fisiologia , Monitorização Fisiológica/instrumentação , Movimento (Física) , Dispositivos Eletrônicos Vestíveis , Fenômenos Biomecânicos , Desenho de Equipamento , Humanos , Perna (Membro)/fisiologia , Redes Neurais de Computação , Reprodutibilidade dos Testes , Coxa da Perna/fisiologia
2.
J Sports Sci ; 38(19): 2200-2207, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32921248

RESUMO

The aims of this study were (a) to describe the kinematics underlying the phenomenon of the knee of the swing leg passing medially in front of the athlete during the single push (SP) phase of the block sprint start, and (b) to determine the relationships between block phase pelvis range of motion (RoM), 1st step width and block phase performance. Three-dimensional kinematic data (250 Hz) were collected from eleven competitive sprinters (100 m PB: 11.17 ± 0.41) performing maximal effort block starts. The joint angles of the rear hip with respect to the pelvis and the pelvis segment angles with respect to the laboratory coordinate system were calculated during the block start phase to the end of the 1st stance. A combination of pelvis list and rotation (not hip adduction) was coupled with the thigh of the swing leg moving medially during the SP phase. A very high positive correlation was found between pelvic list RoM and 1st step width (r = 0.799, p = 0.003). No other significant correlations were found. Attempting to reduce pelvic RoM or changing frontal and transverse plane hip joint angles to minimise medial thigh motion is unlikely to lead to an improvement to performance.


Assuntos
Articulação do Joelho/fisiologia , Pelve/fisiologia , Corrida/fisiologia , Aceleração , Fenômenos Biomecânicos , Feminino , Análise da Marcha , Articulação do Quadril/fisiologia , Humanos , Masculino , Postura/fisiologia , Amplitude de Movimento Articular , Coxa da Perna/fisiologia , Estudos de Tempo e Movimento , Adulto Jovem
3.
Poult Sci ; 99(4): 2230-2235, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32241508

RESUMO

The consumption of meat products from old broiler breeder hen (OBH) and old laying hen (OLH) is limited by their poor organoleptic properties. In this study, the physicochemical properties of breast and thigh meat from OBH and OLH and their application to the development of pressed ham with better quality properties were examined. To manufacture pressed ham, 3 different chicken meat mixtures (mixture A, 50% breast and 50% thigh from OBH; mixture B, 50% breast and 50% thigh meat from OLH; mixture C, 25% breast and 25% thigh from OBH and OLH, respectively) were used. Breast meat from OBH showed a higher water holding capacity (WHC; P < 0.001), a* values (P < 0.05), and tenderness (P < 0.001) and lower cooking loss (P < 0.001) and b* values (P < 0.01) than those of other samples. No significant differences in physicochemical properties of thigh meat were detected between OBH and OLH. Regardless of chicken breed, the thigh samples showed significantly higher pH values, cooking loss, and a* and significantly lower WHC, L*, and b* than those of breast samples. The quality properties of pressed ham were affected by the physicochemical characteristics of meat ingredients, including pH, WHC, and textural properties. The pressed ham samples with mixtures A and B showed the lowest (P < 0.05) and highest (P < 0.05) values, respectively, for cooking loss, L*, b*, hardness, gumminess, and chewiness. The highest (P < 0.05) overall acceptability scores were obtained for samples made with mixture A. Thus, breast and thigh meat from OBH could be used for pressed ham with favorable WHC, tenderness, and overall acceptability.


Assuntos
Carne/análise , Músculos Peitorais/fisiologia , Coxa da Perna/fisiologia , Fatores Etários , Animais , Galinhas , Culinária , Feminino
4.
J Int Soc Sports Nutr ; 17(1): 16, 2020 Mar 12.
Artigo em Inglês | MEDLINE | ID: mdl-32164702

RESUMO

BACKGROUND: The leucine metabolite ß-hydroxy-ß-methylbutyrate (HMB) is widely used as an ergogenic supplement to increase resistance-training induced gains in fat free mass (FFM) and strength in healthy adults. Recent studies have questioned the effectiveness of HMB, particularly when a high protein diet is habitually consumed. To investigate the additive resistance-training induced effects of HMB and protein in untrained individuals, we conducted a randomized double-blind, placebo-controlled study that compared the effects of combined protein and HMB supplementation to protein supplementation alone on FFM and muscle strength after 12-week resistance training. METHODS: Sixteen healthy men (22 ± 2 yrs) performed a periodized resistance-training program for twelve weeks (four sessions per week). The program comprised two mesocycles, characterized by a linear periodization and non-linear periodization, respectively, and separated by a 1-week tapering period. All participants received 60 g of whey protein on training days and 30 g of whey protein (WP) on non-training days. Participants were randomly assigned to additionally receive 3 g of calcium HMB (WP + HMB) or a placebo (WP + PLA). Body composition and physical fitness were tested before and after the 12-week training program. Whole-body and arm and leg fat free mass (FFM) were assessed by bioimpedance spectroscopy; upper arm and leg fat free cross sectional areas were also quantified using magnetic resonance imaging (MRI); upper and lower body strength were measured by One-repetition maximum (1-RM) bench press and leg press. RESULTS: Whole-body and segmental FFM increased in both groups (P <  0.001). However, gains in leg FFM were higher in WP + HMB vs. WP + PLA (arm FFM: + 6.1% vs. + 9.2%, P = 0.2; leg FFM: + 14.2% vs. + 7.0%, P <  0.01). No change in fat mass was observed (P = 0.59). 1-RM increased in both groups (P <  0.001). CONCLUSIONS: Combined protein and HMB supplementation resulted in segmental, but not whole-body increases in FFM compared to protein supplementation alone. These findings could explain some of the controversial effects of HMB reported in previous studies and have practical implications for maximizing training-induced gains in FFM and clinical conditions associated with skeletal muscle deconditioning such as aging, sedentary lifestyles, bed rest and spaceflight.


Assuntos
Cálcio/administração & dosagem , Músculo Esquelético/fisiologia , Substâncias para Melhoria do Desempenho/administração & dosagem , Treinamento de Resistência , Valeratos/administração & dosagem , Proteínas do Soro do Leite/administração & dosagem , Composição Corporal , Suplementos Nutricionais , Método Duplo-Cego , Humanos , Masculino , Coxa da Perna/fisiologia , Adulto Jovem
5.
PLoS One ; 15(3): e0230145, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32163481

RESUMO

Previous studies on joint kinetics during track and field block starts have been limited to lower-limb sagittal kinetics; however, we hypothesised that lumbopelvic extensors, lateral flexors, and hip abductors also act as substantial energy generators. The present study aimed to examine the three-dimensional lumbo-pelvic-hip kinetics to better understand the generation of mechanical energy during a block start. 3D kinematic and force data during block starts of 10 m maximal sprinting in 12 male sprinters (personal best in a 100 m sprint, 10.78 ± 0.19 s [range, 10.43-11.01 s]) were captured using a motion capture system and force platform. The three-dimensional lumbo-pelvic-hip kinetics were calculated. The peak lumbosacral extension torque (3.64 ± 0.39 Nm/kg) was significantly larger than any other lower-limb and lumbosacral torques (<3.0 Nm/kg). It was suggested that large lumbopelvic extension torques are needed during the block start to anchor the pelvis by cancelling out both hip extension torques acting on the pelvis, leading to hip extensor-induced thigh sagittal rotations rather than pelvic posterior tilt. During the double-stance phase, the lumbosacral extensors generated mechanical energy (0.35 ± 0.16 J/kg, 14 ± 4% of the sum of lumbosacral and lower-limb net joint work). During the single-stance phase, the sum of the net mechanical work by lumbosacral lateral flexors and front hip abductors was 0.35 ± 0.14 J/kg, which comprised 9 ± 3% of the sum of the net joint work. The results lead to the speculation of the importance of strengthening not only the leg extensors, but also the lumbopelvic extensors, lateral flexors, and hip abductors for block starts. Further training studies to verify this speculation will improve training strategies for the track and field block start performance.


Assuntos
Desempenho Atlético/fisiologia , Quadril/fisiologia , Pelve/fisiologia , Coxa da Perna/fisiologia , Atletismo/fisiologia , Adulto , Fenômenos Biomecânicos/fisiologia , Articulação do Quadril/fisiologia , Humanos , Cinética , Articulação do Joelho/fisiologia , Masculino , Postura/fisiologia , Corrida/fisiologia , Estudos de Tempo e Movimento , Torque , Adulto Jovem
6.
PLoS One ; 15(2): e0228536, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32049971

RESUMO

Recent literature emphasizes the importance of comfort in the design of exosuits and other assistive devices that physically augment humans; however, there is little quantitative data to aid designers in determining what level of force makes users uncomfortable. To help close this knowledge gap, we characterized human comfort limits when applying forces to the shoulders, thigh and shank. Our objectives were: (i) characterize the comfort limits for multiple healthy participants, (ii) characterize comfort limits across days, and (iii) determine if comfort limits change when forces are applied at higher vs. lower rates. We performed an experiment (N = 10) to quantify maximum tolerable force pulling down on the shoulders, and axially along the thigh and shank; we termed this force the comfort limit. We applied a series of forces of increasing magnitude, using a robotic actuator, to soft sleeves around their thigh and shank, and to a harness on their shoulders. Participants were instructed to press an off-switch, immediately removing the force, when they felt uncomfortable such that they did not want to feel a higher level of force. On average, participants exhibited comfort limits of ~0.9-1.3 times body weight on each segment: 621±245 N (shoulders), 867±296 N (thigh), 702±220 N (shank), which were above force levels applied by exosuits in prior literature. However, individual participant comfort limits varied greatly (~250-1200 N). Average comfort limits increased over multiple days (p<3e-5), as users habituated, from ~550-700 N on the first day to ~650-950 N on the fourth. Specifically, comfort limits increased 20%, 35% and 22% for the shoulders, thigh and shank, respectively. Finally, participants generally tolerated higher force when it was applied more rapidly. These results provide initial benchmarks for exosuit designers and end-users, and pave the way for exploring comfort limits over larger time scales, within larger samples and in different populations.


Assuntos
Desenho de Equipamento , Exoesqueleto Energizado , Perna (Membro)/fisiologia , Mialgia/prevenção & controle , Conforto do Paciente , Pressão/efeitos adversos , Ombro/fisiologia , Adulto , Tornozelo/fisiologia , Fenômenos Biomecânicos , Desenho de Equipamento/efeitos adversos , Desenho de Equipamento/métodos , Exoesqueleto Energizado/efeitos adversos , Feminino , Marcha/fisiologia , Humanos , Masculino , Mialgia/etiologia , Conforto do Paciente/métodos , Robótica/instrumentação , Robótica/métodos , Estresse Mecânico , Coxa da Perna/fisiologia , Adulto Jovem
7.
J Sci Med Sport ; 23(5): 524-528, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-31928881

RESUMO

OBJECTIVES: Investigate the determinants of hamstring fascicle length in professional rugby league players. DESIGN: Retrospective cohort study METHODS: Thirty-three elite male athletes underwent testing in the pre-season and in-season periods. Fascicle length measurements of the biceps femoris long head, 3D kinematics and elapsed time-periods at thigh angular velocities between 20°/s to peak velocity during a single-leg Nordic hamstring strength test, GPS-derived running loads, age and previous injury history were all recorded. Fixed effect determinants for fascicle length were analyzed using multiple linear regression. RESULTS: Significant determinants of hamstring fascicle length were observed. Multivariate regression analysis showed modifiable factors including chronic (56 days) running volumes >80% of measured peak velocity and maximum velocity itself collectively explained 43% of the variability in the fascicle length data, whilst peak eccentric strength and elapsed time under load from 20°/s to peak thigh angular velocity collectively contributed an additional 44%. Chronic running volumes >90% of individually measured peak velocity and the 'break angle' during a Nordic eccentric contraction were not significant contributors to the final model. Non-modifiable risk factors (age and previous injury) contributed the remaining 13%. CONCLUSIONS: Managing high velocity running exposure as well as eccentric strength allows for ˜90% of the controllable determinants in fascicle length within elite athlete populations. An important contributor to the explained variability within fascicle length (superseded only by chronic velocity exposure and peak eccentric strength) was an athletes ability to achieve a prolonged contraction at long lengths during eccentric strength training rather than the angle of failure during the contraction in itself.


Assuntos
Futebol Americano/fisiologia , Músculos Isquiossurais/fisiologia , Força Muscular , Corrida/fisiologia , Coxa da Perna/fisiologia , Adulto , Fenômenos Biomecânicos , Sistemas de Informação Geográfica , Músculos Isquiossurais/anatomia & histologia , Humanos , Masculino , Estudos Retrospectivos , Adulto Jovem
8.
Med Sci Sports Exerc ; 52(7): 1563-1575, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-31977639

RESUMO

INTRODUCTION: Chronic ankle instability (CAI) is known to induce impairments throughout the lower quarter kinetic chain, however there is currently no synthesized information on proximal adaptations of the trunk, hip, thigh, and knee for neuromuscular and biomechanical outcomes during strength, balance, jumping, and gait among CAI patients. The purpose of this systematic review and meta-analysis was to synthesize trunk, hip, thigh and knee neuromuscular and biomechanical outcome measures during functional assessments when comparing CAI to healthy groups. METHODS: Cumulative Index of Nursing and Allied Health Literature and Medical Literature Analysis and Retrieval System Online with PubMed databases were searched on June 3, 2019. Studies comparing outcomes at the trunk, hip, thigh, or knee regardless of assessment type in CAI versus healthy groups were considered for inclusion. Assessment categories were used to differentiate adaptations by assessment type after inclusion. Two independent reviewers assessed methodological quality using the Physiotherapy Evidence Database scoring criteria. Data pertaining to study methodology and primary proximal adaptation outcomes were extracted. Separate random effects meta-analyses were performed for consistently reported outcome measures. RESULTS: Pooled estimates reflected that CAI patients had decreased triplanar isometric hip strength outcomes (P < 0.001, effect size range: 0.52-0.93). Knee kinematics did not differ from healthy groups during dynamic balance testing (P = 0.26). Few studies found CAI patients have altered knee kinematics during jumping tasks. The remaining findings were isolated to individual studies and thus inconclusive. CONCLUSIONS: The CAI groups demonstrated triplanar hip strength deficits and altered knee flexion angles during jumping assessments. Clinicians should consider proximal evaluations and interventions for CAI patients.


Assuntos
Adaptação Fisiológica , Traumatismos do Tornozelo/fisiopatologia , Articulação do Tornozelo/fisiopatologia , Instabilidade Articular/fisiopatologia , Doença Crônica , Análise da Marcha , Quadril/fisiologia , Humanos , Joelho/fisiologia , Força Muscular , Exercício Pliométrico , Equilíbrio Postural , Entorses e Distensões/fisiopatologia , Coxa da Perna/fisiologia , Tronco/fisiologia
9.
Fisioter. Pesqui. (Online) ; 27(1): 16-21, jan.-mar. 2020. tab, graf
Artigo em Português | LILACS | ID: biblio-1090412

RESUMO

RESUMO O objetivo deste estudo foi verificar se a formação do arco longitudinal do pé interfere na distribuição da pressão plantar e na flexibilidade dos músculos posteriores da coxa. O método de estudo foi transversal e as impressões plantares foram obtidas usando o plantígrafo e analisadas segundo o método Viladot. A distribuição plantar e a flexibilidade foram avaliadas pela baropodometria e pelo banco de Wells, respectivamente. Foi observado que crianças com pés cavos apresentam maior flexibilidade quando comparadas às que têm o pé normal (p=0,02); e também que pés cavos apresentam maior pressão, ou seja, maior sobrecarga em calcâneo quando comparados àqueles com o arco plantar normal (p=0,02 membro inferior direito e p=0,03 membro inferior esquerdo). A avaliação do arco longitudinal medial mostra que crianças com pés cavos apresentam maior flexibilidade dos músculos posteriores de membro inferior. Os pés cavos também estão associados com maior descarga de peso em região de calcâneo.


RESUMEN El objetivo de este estudio fue verificar si la formación del arco longitudinal del pie interfiere con la distribución de la presión plantar y la flexibilidad de los músculos posteriores del muslo. El método de estudio fue transversal y las huellas plantar se obtuvieron utilizando el plantigraph y se analizaron según el método de Viladot. La distribución plantar y la flexibilidad se evaluaron mediante baropodometría y el banco de Wells, respectivamente. Se observó que los niños con pies huecos tienen mayor flexibilidad en comparación con aquellos con pies normales (p=0,02); y también que los pies huecos tienen una mayor presión, es decir, una mayor sobrecarga del talón en comparación con aquellos con arco plantar normal (p=0,02 miembro inferior derecho y p=0,03 miembro inferior izquierdo). La evaluación del arco longitudinal medial muestra que los niños con pies huecos tienen una mayor flexibilidad en los músculos posteriores de la extremidad inferior. Los pies huecos también están asociados con una mayor descarga de peso en la región del talón.


ABSTRACT Objective: To evaluate whether the formation of the longitudinal arch of the foot interferes with the distribution of plantar pressure and the pliability of the posterior thigh muscles. Methodology: a cross-sectional study and the footprints were obtained using the footprinting mat and analyzed according to the Viladot method. Plantar distribution and pliability were assessed by baropodometry and Wells' bank, respectively. Results: It was observed that children with cavus feet present greater pliability when compared to those with normal feet (p=0.02). Also, the cavus feet exhibit higher pressure, that is, a greater heel overload compared to those with normal plantar arch (p=0.02 lower right limb and p=0.03 lower left limb). Conclusions: The evaluation of the medial longitudinal arch shows that children with cavus feet have greater pliability of the lower limb posterior muscles. The cavus feet are also associated with higher pressure in the calcaneal region.


Assuntos
Humanos , Masculino , Feminino , Criança , Coxa da Perna/fisiologia , Amplitude de Movimento Articular/fisiologia , Músculo Esquelético/fisiologia , Pé/fisiologia , Fenômenos Biomecânicos/fisiologia , Estatura , Pesos e Medidas Corporais , Índice de Massa Corporal , Estudos Transversais , Suporte de Carga/fisiologia , Equilíbrio Postural/fisiologia , Pé Cavo/fisiopatologia
10.
Scand J Med Sci Sports ; 30(2): 303-311, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31605551

RESUMO

There is strong evidence linking an athlete's movement technique during sidestepping with anterior cruciate ligament (ACL) injury risk. However, it is unclear how these injurious postures are influenced by prior movement. We aim to describe preparatory trunk and thigh kinematics at toe-off of the penultimate-step and flight-phase angular momenta, and explore their associations with frontal-plane risk factors during unplanned sidestepping maneuvers. We analyzed kinematic and kinetic data of 33 male Australian Football players performing unplanned sidestepping tasks (103 trials). Linear mixed models tested for reliable associations between ACL injury risk during weight acceptance of the execution-step, with preparatory kinematics and angular momenta of the trunk and thigh during the penultimate-step. Multi-planar flight-phase trunk momenta along with hip abduction angle at penultimate-step toe-off were significantly associated with peak knee valgus moments during the execution-step (R2  = .21, P < .01). Execution-step trunk lateral flexion was significantly predicted by frontal and sagittal-plane preparatory trunk positioning at toe-off of the penultimate-step (R2  = .44, P < .01). Multi-planar flight-phase trunk momenta as well as multi-planar trunk and hip positioning at penultimate-step toe-off were associated with hip abduction during the execution-step (R2  = .53, P < .01). Preparatory positioning of the trunk and hip, along with flight-phase trunk momentum adjusting this positioning are linked to known ACL injury risk factors. We recommend that during the penultimate-step athletes maintain an upright trunk, as well as minimize frontal-plane trunk momentum and transverse-plane trunk momentum toward the sidestep direction to reduce risk of ACL injury during unplanned sidesteps.


Assuntos
Lesões do Ligamento Cruzado Anterior/prevenção & controle , Movimento , Coxa da Perna/fisiologia , Tronco/fisiologia , Adolescente , Adulto , Atletas , Austrália , Fenômenos Biomecânicos , Futebol Americano , Humanos , Joelho/fisiologia , Masculino , Postura , Adulto Jovem
11.
Sports Biomech ; 19(3): 322-332, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-29912644

RESUMO

A case study visualisation approach to examining the coordination and variability of multiple interacting segments is presented using a whole-body gymnastic skill as the task example. One elite male gymnast performed 10 trials of 10 longswings whilst three-dimensional locations of joint centres were tracked using a motion analysis system. Segment angles were used to define coupling between the arms and trunk, trunk and thighs and thighs and shanks. Rectified continuous relative phase profiles for each interacting couple for 80 longswings were produced. Graphical representations of coordination couplings are presented that include the traditional single coupling, followed by the relational dynamics of two couplings and finally three couplings simultaneously plotted. This method highlights the power of visualisation of movement dynamics and identifies properties of the global interacting segmental couplings that a more formal analysis may not reveal. Visualisation precedes and informs the appropriate qualitative and quantitative analysis of the dynamics.


Assuntos
Ginástica/fisiologia , Destreza Motora/fisiologia , Braço/fisiologia , Fenômenos Biomecânicos , Humanos , Joelho/fisiologia , Masculino , Movimento , Ombro/fisiologia , Coxa da Perna/fisiologia , Estudos de Tempo e Movimento , Tronco/fisiologia , Adulto Jovem
12.
Sports Biomech ; 19(4): 532-546, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-30102119

RESUMO

This study examined the validity of various scaling methods, isometric mid-thigh pull (IMTP) peak force using various scaling methods, and the relationships between IMTP peak force and countermovement jump height.  Fifty-one collegiate baseball and soccer athletes performed two maximal IMTPs.  Absolute peak force was compared between teams and when data were scaled using ratio (RS), traditional allometric (ALLOTrad), and fitted allometric (ALLOFit) scaling.  ALLOTrad and ALLOFit validity was violated because different derived exponents existed for baseball (b = 0.20) and soccer (b = 1.20).  Soccer athletes produced greater RS peak force compared to baseball (p = 0.012), while no difference existed with absolute, ALLOTrad or ALLOFit (all p > 0.05) peak force.  Moderate relationships existed between body mass and absolute (r = 0.402, p = 0.003) and RS (r = -0.328, p = 0.019) peak force, while trivial relationships existed with ALLOTrad and ALLOFit (both r < -0.10, p > 0.05).  Trivial relationships existed between countermovement jump height and absolute, RS, ALLOTrad, and ALLOFit (all r < 0.20, p > 0.05) peak force.  The current dataset violated allometric scaling assumptions, making it inappropriate to use ALLOTrad and ALLOFit scaling.  Practitioners must understand the assumptions, limitations, and purpose of scaling methods.


Assuntos
Beisebol/fisiologia , Índice de Massa Corporal , Teste de Esforço/métodos , Força Muscular/fisiologia , Futebol/fisiologia , Coxa da Perna/fisiologia , Adolescente , Fenômenos Biomecânicos , Estudos Transversais , Humanos , Contração Isométrica/fisiologia , Músculo Esquelético/fisiologia , Exercício Pliométrico , Reprodutibilidade dos Testes , Adulto Jovem
13.
IEEE Trans Neural Syst Rehabil Eng ; 28(1): 267-276, 2020 01.
Artigo em Inglês | MEDLINE | ID: mdl-31675333

RESUMO

As surface electromyogram (sEMG) signals have the ability to detect human movement intention, they are commonly used to be control inputs. However, gait sub-phase classification typically requires monotonous manual labeling process, and commercial sEMG acquisition devices are quite bulky and expensive, thus current sEMG-based gait sub-phase recognition systems are complex and have poor portability. This study presents a low-cost but effective end-to-end sEMG-based gait sub-phase recognition system, which contains a wireless multi-channel signal acquisition device simultaneously collecting sEMG of thigh muscles and plantar pressure signals, and a novel neural network-based sEMG signal classifier combining long-short term memory (LSTM) with multilayer perceptron (MLP). We evaluated the system with subjects walking under five conditions: flat terrain at 5 km/h, flat terrain at 3 km/h, 20 kg backpack at 5 km/h, 20 kg shoulder bag at 5 km/h and 15° slope at 5 km/h. Experimental results show that the proposed method achieved average classification accuracies of 94.10%, 87.25%, 90.71%, 94.02%, and 87.87%, respectively, which were significantly higher than existing recognition methods. Additionally, the proposed system had a good real-time performance with low average inference time in the range of 3.25 ~ 3.31 ms.


Assuntos
Eletromiografia/instrumentação , Marcha/fisiologia , Adulto , Algoritmos , Fenômenos Biomecânicos , Custos e Análise de Custo , Eletromiografia/economia , Eletromiografia/métodos , Desenho de Equipamento , Pé/fisiologia , Humanos , Locomoção/fisiologia , Masculino , Músculo Esquelético/fisiologia , Redes Neurais de Computação , Pressão , Reprodutibilidade dos Testes , Coxa da Perna/fisiologia
14.
Knee Surg Sports Traumatol Arthrosc ; 28(2): 637-644, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31734705

RESUMO

PURPOSE: The gracilis tendon is a commonly used autologous graft. Most information on knee function and outcomes after its harvest is related to both semitendinosus- and gracilis tendon harvest. Therefore this study analyzed the effect of isolated gracilis tendon harvest from healthy, uninjured knees on thigh muscle strength and patient reported outcome measures (PROMs). METHODS: Stabilization of the acromioclavicular joint because of chronic instability was performed with autologous gracilis tendon in 12 patients. After a mean of 44 ± 25 months after surgery, isokinetic peak-torque measurements of specific functions of the gracilis muscle were performed: knee flexion in a sitting position (flexion angles 0-90°) and in prone position (flexion angles > 70°), internal tibial rotation and hip adduction. The contralateral limb was control. Knee specific PROMs were collected including IKDC-2000 subjective evaluation form, Lysholm score, the Marx Activity Rating Scale and SF-36 health survey. RESULTS: No significant side-to-side differences were found regarding torque measurements. Excellent results were shown regarding the PROMs, which even in terms of IKDC-2000 (97 vs. 82 points, p = 0.001) exceeded significantly the age- and gender matched reference-data. CONCLUSION: Isolated gracilis tendon harvesting was not associated with loss of strength in knee flexion, internal tibial rotation and thigh adduction. Additionally, good functional outcome as well as excellent knee-specific subjective outcome was found. LEVEL OF EVIDENCE: III.


Assuntos
Articulação Acromioclavicular/cirurgia , Músculo Grácil/transplante , Instabilidade Articular/cirurgia , Força Muscular/fisiologia , Coleta de Tecidos e Órgãos/métodos , Adulto , Autoenxertos , Feminino , Humanos , Joelho/fisiologia , Masculino , Pessoa de Meia-Idade , Medidas de Resultados Relatados pelo Paciente , Amplitude de Movimento Articular , Rotação , Coxa da Perna/fisiologia , Tíbia/fisiologia , Torque
15.
Sports Biomech ; 19(1): 1-25, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-29781788

RESUMO

The use of isometric strength testing, particularly the isometric mid-thigh pull (IMTP) has increased dramatically over the last decade. The IMTP and isometric squat (ISqT) provide one aspect of performance monitoring with variables such as peak force and rate of force development being derived from the force-time curve. The reliability of some of these variables is conflicting in the literature, and the reporting of the reliability is not standardised across the research. The majority of research only reports intraclass correlation coefficients with very few studies reporting coefficient of variation and 90% confidence intervals. Additionally, methods used to calculate variables from the force-time curve differ across studies. An aim of muscle strength testing is to provide normative values for specific sports, allowing coaches to distinguish between performance levels or evaluate the effects of training on performance. This narrative review aims to evaluate studies that have researched the reliability and/or reported normative data for both tests. Additionally, the testing protocols and the force-time curve analysis techniques utilised are discussed, concluding with practical applications for coaches on the uses and limitations of these tests. Results demonstrate that peak force is the most reliable measure and can be used to determine maximum strength capabilities.


Assuntos
Teste de Esforço/métodos , Força Muscular/fisiologia , Coxa da Perna/fisiologia , Levantamento de Peso , Fenômenos Biomecânicos , Humanos , Contração Isométrica/fisiologia , Valores de Referência , Reprodutibilidade dos Testes , Esportes/fisiologia
16.
BMC Musculoskelet Disord ; 20(1): 512, 2019 Nov 03.
Artigo em Inglês | MEDLINE | ID: mdl-31679520

RESUMO

BACKGROUND: Meniscus injury and meniscectomy both entail increased risk of knee osteoarthritis (OA). Thigh muscle weakness is a suggested mediator of OA but there is little evidence of its importance for knee OA development after meniscectomy. This study aimed to examine the association between thigh muscle strength after partial meniscectomy in middle-aged subjects with a non-traumatic meniscal tear and later radiographic knee OA changes. METHODS: Thirty-four out of 45 participants in an exercise-trial underwent testing for isokinetic thigh muscle strength 4 years after arthroscopic partial meniscectomy and had radiographic examination 11 years later (15 years post-surgery, mean age at follow-up of 57 years (range 50-61)). Outcomes were grade of joint space narrowing and osteophyte score in the medial tibiofemoral compartment of the operated knee and the contralateral knee. We tested the association between muscle strength at baseline and the radiographic outcomes at follow-up using logistic regression analyses adjusted for sex and overweight. RESULTS: At follow-up, 33/34 subjects had joint space narrowing and 27/34 subjects had osteophytes in the operated knee, in the contralateral knee joint space narrowing was found in 23 subjects. In the operated knee baseline knee extensor and flexor strength were negatively associated with grade of joint space narrowing at follow-up (OR 0.972 and 0.956, p = 0.028 and 0.026, respectively) and also with osteophyte score (OR 0.968 and 0.931, p = 0.017 and 0.011, respectively). In the contralateral knee longitudinal associations between strength and radiographic OA features were similar, OR 0.949-0.972, p < 0.05. CONCLUSION: The finding that stronger thigh muscles 4 years after meniscectomy were associated with less severe osteoarthritic changes in the medial tibiofemoral compartment of both the operated and contralateral knee 11 years later, may suggest that strong thigh muscles can help to preserve joint integrity in middle-aged subjects at risk of knee OA.


Assuntos
Meniscectomia/tendências , Força Muscular/fisiologia , Osteoartrite do Joelho/diagnóstico por imagem , Osteoartrite do Joelho/cirurgia , Coxa da Perna/diagnóstico por imagem , Coxa da Perna/fisiologia , Feminino , Seguimentos , Humanos , Masculino , Meniscectomia/métodos , Pessoa de Meia-Idade , Músculo Esquelético/diagnóstico por imagem , Músculo Esquelético/fisiologia , Fatores de Tempo
17.
Artigo em Inglês | MEDLINE | ID: mdl-31752177

RESUMO

(1) Background: Squatting is one of the common closed-kinetic chain (CKC) exercises for knee rehabilitation. Some patients cannot perform squatting exercises on land occasionally due to knee pain. Several studies had suggested that lower limb muscle activities are lower in water than on land while performing CKC exercises. The purpose of this study is to investigate the surface electromyography (sEMG) activities of Rectus femoris (RF) and Biceps femoris (BF) muscles when doing a squatting exercise in water and on land. (2) Methods: This was a cross-sectional experimental study. A total of 20 healthy participants (10 males, 10 females) were recruited by convenience sampling. The sEMG of RF and BF muscles in water and on land were collected and the knee motions were videotaped. Participants were instructed to perform closed kinetic-chain back squatting exercises at a specific speed (30 beats per minute) in water and on land at angular speed of 45°/s. Eight repetitions of the squatting exercise (0-90° knee flexion) were performed. The mean percentage maximal voluntary contraction (%MVC) between two muscles was compared in two conditions. The %MVC of RF and BF muscles at different specific knee flexion angles (30°, 60° and 90° knee flexion) was also identified. (3) Result: Muscle activities of RF (p = 0.01) and BF (p < 0.01) muscles were significantly lower in water than on land. The %MVC of RF and BF muscles was found to be 15.01% and 10.68% lower in water than on land respectively. For different knee angle phases, the differences in %MVC between land and water had significant difference for both RF muscles and BF muscles. (4) Conclusion: This study found a difference of mean percentage MVC of RF and BF muscles between land and water in different phases of squatting. The water medium reduced the two muscles' activities to a similar extent. The result showed that the aquatic environment allows an individual to perform squatting with less muscle activation which may serve as an alternative knee exercise option for patients who encounter difficulty in land squatting due to lower limb muscle weakness or a high level of knee pain.


Assuntos
Eletromiografia , Hidroterapia , Contração Muscular , Músculo Esquelético/fisiologia , Coxa da Perna/fisiologia , Estudos Transversais , Exercício Físico/fisiologia , Terapia por Exercício , Feminino , Voluntários Saudáveis , Humanos , Joelho , Articulação do Joelho/fisiologia , Extremidade Inferior , Masculino , Postura , Água , Adulto Jovem
18.
Hawaii J Health Soc Welf ; 78(11 Suppl 2): 41-46, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31773110

RESUMO

Atrophy and protracted recovery of normal function of the ipsilateral quadriceps femoris muscle following anterior cruciate ligament reconstruction surgery is well documented. The Accelerated Recovery Performance trainer is a type of electrical stimulation device that delivers a high-pulse frequency via a direct current, making it unique from many other devices on the market. The purpose of the present study was to investigate the effects of the direct current (via the Accelerated Recovery Performance trainer protocol) on gains in thigh circumference following anterior cruciate ligament reconstruction. Twenty-five patients were enrolled following isolated anterior cruciate ligament reconstruction and randomly assigned to either an isometric rehabilitation protocol augmented with the Accelerated Recovery Performance trainer protocol (experimental group) or the isometric rehabilitation protocol alone (control group). The two groups participated in sixteen sessions of directed rehabilitation over a two-month time period. Patients were followed with serial thigh circumference measurements at 5, 10, 15, and 20 centimeters above the superior patellar pole. Comparison of the overall mean circumferential gains in thigh circumference of the involved leg demonstrated approximately 3:1 gains in the ARP group over the control group, demonstrating it to be superior to isometric rehabilitation alone with regards to gains in thigh girth. The Accelerated Recovery Performance trainer protocol should be considered for post-anterior cruciate ligament reconstruction rehabilitation in order to reverse disuse atrophy of the ipsilateral quadriceps femoris.


Assuntos
Reconstrução do Ligamento Cruzado Anterior/reabilitação , Terapia por Estimulação Elétrica , Músculos/fisiopatologia , Período Pós-Operatório , Músculo Quadríceps/fisiologia , Adulto , Feminino , Humanos , Masculino , Coxa da Perna/fisiologia
19.
J Biomech ; 97: 109416, 2019 Dec 03.
Artigo em Inglês | MEDLINE | ID: mdl-31630774

RESUMO

Wearable inertial measurement units (IMU) have been proposed to estimate GRF outside of specialized laboratories, however the precise influence of sensor placement error on accuracy is unknown. We investigated the influence of IMU position and orientation placement errors on GRF estimation accuracy. METHODS: Kinematic data from twelve healthy subjects based on marker trajectories were used to simulate 1848 combinations of sensor position placement errors (range ±â€¯100 mm) and orientation placement errors (range ±â€¯25°) across eight body segments (trunk, pelvis, left/right thighs, left/right shanks, and left/right feet) during normal walking trials for baseline cases when a single sensor was misplaced and for the extreme cases when all sensors were simultaneously misplaced. Three machine learning algorithms were used to estimate GRF for each placement error condition and compared with the no placement error condition to evaluate performance. RESULTS: Position placement errors for a single misplaced IMU reduced vertical GRF (VGRF), medio-lateral GRF (MLGRF), and anterior-posterior GRF (APGRF) estimation accuracy by up to 1.1%, 2.0%, and 0.9%, respectively and for all eight simultaneously misplaced IMUs by up to 4.9%, 6.0%, and 4.3%, respectively. Orientation placement errors for a single misplaced IMU reduced VGRF, MLGRF, and APGRF estimation accuracy by up to 4.8%, 7.3%, and 1.5%, respectively and for all eight simultaneously misplaced IMUs by up to 20.8%, 23.4%, and 12.3%, respectively. CONCLUSION: IMU sensor misplacement, particularly orientation placement errors, can significantly reduce GRF estimation accuracy and thus measures should be taken to account for placement errors in implementations of GRF estimation via wearable IMUs.


Assuntos
Caminhada/fisiologia , Dispositivos Eletrônicos Vestíveis , Fenômenos Biomecânicos , Pé/fisiologia , Humanos , Perna (Membro)/fisiologia , Aprendizado de Máquina , Coxa da Perna/fisiologia , Tronco/fisiologia
20.
J Athl Train ; 54(12): 1304-1307, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31657637

RESUMO

CONTEXT: When using an ice bag, previous researchers recommended cooling times based on the amount of subcutaneous tissue. Unfortunately, many clinicians are unaware of these recommendations or whether they can be applied to other muscles. OBJECTIVE: To examine if muscles of the lower extremity cool similarly based on recommended cooling times. DESIGN: Crossover study. SETTING: Athletic training laboratory. PATIENTS OR OTHER PARTICIPANTS: Fourteen healthy participants volunteered (8 men, 6 women; age = 21.1 ± 2.2 years, height = 174.2 ± 4.5 cm, weight = 74.0 ± 7.5 kg). INTERVENTION(S): Subcutaneous tissue thickness was measured at the largest girth of the thigh, medial gastrocnemius, and medial hamstring. Participants were randomized to have either the rectus femoris or medial gastrocnemius and medial hamstring tested first. Using sterile techniques, the examiner inserted a thermocouple 1 cm into the muscle after accounting for subcutaneous tissue thickness. After the temperature stabilized, a 750-g ice bag was applied for 10 to 60 minutes to the area(s) for the recommended length of time based on subcutaneous adipose thickness (0 to 5 mm [10 minutes]; 5.5 to 10 mm (25 minutes]; 10.5 to 15 mm [40 minutes]; 15.5 to 20 mm [60 minutes)]. After the ice bag was removed, temperature was monitored for 30 minutes. At least 1 week later, each participant returned to complete testing of the other muscle(s). MAIN OUTCOME MEASURE(S): Intramuscular temperature (°C) at baseline, end of treatment time (0 minutes), and posttreatment recovery (10, 20, and 30 minutes postintervention). RESULTS: At the end of treatment, temperature did not differ by subcutaneous tissue thickness (10 minutes = 29.0°C ± 3.8°C, 25 minutes = 28.7°C ± 3.2°C, 40 minutes = 28.7°C ± 6.0°C, 60 minutes = 30.0°C ± 2.9°C) or muscle (rectus femoris = 30.1°C ± 3.8°C, gastrocnemius = 28.6°C ± 5.4°C, hamstrings = 28.1°C ± 2.5°C). No significant interaction was present for subcutaneous tissue thickness or muscle (P ≥ .126). CONCLUSIONS: Lower extremity muscles seemed to cool similarly based on the recommended cooling times for subcutaneous tissue thickness. Clinicians should move away from standardized treatment times and adjust the amount of cooling time by ice-bag application based on subcutaneous tissue thickness.


Assuntos
Temperatura Baixa , Músculos Isquiossurais/fisiologia , Músculo Esquelético/fisiologia , Tela Subcutânea/fisiologia , Adolescente , Adulto , Estudos Cross-Over , Crioterapia/métodos , Feminino , Voluntários Saudáveis , Humanos , Perna (Membro)/fisiologia , Masculino , Coxa da Perna/fisiologia , Adulto Jovem
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