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1.
Front Med (Lausanne) ; 10: 1269874, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-38076248

RESUMO

Introduction: Vestibular hypofunction is associated with dizziness, imbalance, and blurred vision with head movement. Vestibular rehabilitation is the gold standard recommendation to decrease symptoms and improve postural stability. The Clinical Practice Guidelines for vestibular hypofunction suggest home exercises 3-5 times daily, but patient adherence is a problem, with compliance rates often below 50%. Methods: An app was developed to increase engagement with home exercises by providing exercises as games. This study compared the accuracy of exercise performance in a one-time session using the app versus no-app and gathered participant feedback on using the app for vestibulo-ocular reflex (VOR) and balance exercises. The app was tested with 40 adults (20 women), mean age of 67 ± 5.7 years, with symptomatic unilateral or bilateral vestibular hypofunction. Participants completed VOR exercises in pitch and yaw planes, weight-shift, and single-leg balance exercises using an inertial motion unit to move the character on the tablet screen. Participants were randomly assigned to begin the exercises with or without the app. Results: Results show that during VOR exercises, participants achieved the prescribed frequency of head motion for the yaw plane (p ≤ 0.001) and reduced variability of head movement frequency in both the yaw (p ≤ 0.001) and pitch plane (p ≤ 0.001) in the app compared to the no-app condition. During weight-shifting exercises, a larger range of body motion was noted in the anteroposterior and mediolateral directions in the app compared to the no-app condition (p < 0.05). During single-leg balance exercises, pelvic motion was lower in the app versus no-app condition (p = 0.02). Participants modified their exercise performance and corrected their mistakes to a greater extent when they used the app during the VOR exercises. Participants agreed that they felt motivated while playing the games (97%) and felt motivated by the trophies (92%). They agreed that the app would help them perform the exercises at home (95%), improve their rehab performance (95%) and that it was fun to do the exercises using the app (93%). Discussion: The results of this study show that technology that is interactive and provides feedback can be used to increase accuracy and engagement with exercises.

2.
Front Neurol ; 13: 836571, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35280295

RESUMO

Close to half people over 60 years of age experience vestibular dysfunction. Although vestibular rehabilitation has been proven effective in reducing dizziness and falls in older adults, adherence to exercise programs is a major issue and reported to be below 50%. Therefore, this research aimed to develop an app with gaming elements to improve adherence to exercises that are part of vestibular rehabilitation, and to provide feedback to increase the accuracy during exercise performance. A clinician-informed design was used where five physical therapists were asked identical questions about the exercises they would like to see in the app, including their duration and frequency. Games were developed to train the vestibulo-ocular (VOR) reflex using VOR and gaze shifting exercises; and to train the vestibulo-spinal system using weight shifting and balance exercises. The games were designed to progress from simple to more complex visuals. The games were controlled by an Inertial Measurement Unit placed on the head or anterior waist. The app was tested on ten healthy females (69.1 ± 5.1 years) with no prior history of vestibular dysfunction or complaints of dizziness. Participants completed gaze stabilization and balance exercises using the app and provided feedback on the user interface, ease of use, usefulness and enjoyment using standardized questionnaires and changes they would like to see in the form of open-ended questions. In general, participants reported that they found the app easy to use, the user interface was friendly, and they enjoyed playing the games due to the graphics and colors. They reported that the feedback provided during the exercise session helped them recognize their mistakes and motivated them to do better. However, some elements of the app were frustrating due to incomplete instructions and inability to distinguish game objects due to insufficient contrast. Feedback received will be implemented in a revised version which will be trialed in older adults with dizziness due to vestibular hypofunction. We have demonstrated that the "Vestibular AppTM" created for rehabilitation with gaming elements was found to be enjoyable, useful, and easy to use by healthy older adults. In the long term, the app may increase adherence to vestibular rehabilitation.

3.
J Trauma Acute Care Surg ; 91(2S Suppl 2): S107-S112, 2021 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-34117168

RESUMO

BACKGROUND: Virtual representations of human internal anatomy are important for military applications such as protective equipment design, injury severity prediction, thermal analysis, and physiological simulations. High-fidelity volumetric models based on imaging data are typically in static postures and difficult to use in simulations of realistic mission scenarios. This study aimed to investigate a hybrid approach to reposition medical avatars that preserves internal anatomy but allows rapid repositioning of full three-dimensional (3D) meshes. METHODS: A software framework that accepts a medical avatar in a 3D tetrahedral mesh format representing 72 organs and tissues with an articulated skeleton was developed. The skeleton is automatically resized and associated to the avatar using rigging and skinning algorithms inspired by computer animation techniques. Military relevant motions were used for animations. A motion retargeting algorithm was implemented to apply animation to avatars of various sizes, and a motion blending algorithm was implemented to smoothly transition between movements. These algorithms were incorporated into a path generation tool that accepts initial, intermediate, and final coordinates of a multisegment action along with the specific motion for each segment to synthesize a realistic compound set of movements comprising the animation. RESULTS: The developed pipeline for dynamic repositioning of medical avatars was demonstrated. Various complex motions were automatically animated. Retargeting was demonstrated on models of varying sizes. Movements along a path were animated to demonstrate smooth motion transitions. Animation of the full 3D avatar mesh ran in real time on a standard desktop personal computer. The repositioning algorithm successfully preserved the shape and volume of rigid structures such as bone. CONCLUSION: The developed software leverages techniques from various disciplines to create a hybrid approach enabling real-time 3D mesh repositioning appropriate for use in simulated military missions using avatars containing a complete anatomy representation. The workflow is largely automated, enabling rapid evaluation of new mission scenarios.


Assuntos
Medicina Militar/métodos , Interface Usuário-Computador , Algoritmos , Realidade Aumentada , Humanos , Militares , Software
4.
PLoS One ; 15(1): e0219954, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31990914

RESUMO

A new methodology was developed to quickly generate whole body models with detailed neck musculoskeletal architecture that are properly scaled in terms of anthropometry and muscle strength. This method was implemented in an anthropometric model generation software that allows users to interactively generate any new male or female musculoskeletal models with adjustment of anthropometric parameters (such as height, weight, neck circumference, and neck length) without the need of subject-specific motion capture or medical images. 50th percentile male and female models were developed based on the 2012 US Army Anthropometric Survey (ANSUR II) database and optimized with a novel bilevel optimization method to have strengths comparable to experimentally measured values in the literature. Other percentile models (ranging from the 1st to 99th percentile) were generated based on anthropometric scaling of the 50th percentile models and compared. The resultant models are reasonably accurate in terms of both musculoskeletal geometry and neck strength, demonstrating the effectiveness of the developed methodology for interactive neck model generation with anthropometric scaling.


Assuntos
Antropometria/métodos , Modelos Anatômicos , Sistema Musculoesquelético/anatomia & histologia , Pescoço/anatomia & histologia , Adulto , Estatura , Peso Corporal , Feminino , Humanos , Contração Isométrica/fisiologia , Masculino , Força Muscular/fisiologia , Pescoço/fisiologia , Software
5.
J Mot Behav ; 49(6): 640-649, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-28136140

RESUMO

Knee rehabilitation exercises to improve motor control, target movement fluency, and displacement variability. Although knee movement in the frontal plane during exercise is routinely assessed in clinical practice, optimal knee control remains poorly understood. In this study, 29 healthy participants (height: 1.73 ± 0.11 m, mass: 73.5 ± 16.4 kg, age: 28.0 ± 6.9 years) performed 4 repetitions of 5 rehabilitation exercises while motion data were collected using the VICON PlugInGait full-body marker set. Fluency and displacement variability were calculated for multiple landmarks, including center of mass (CoM) and knee joint centers. Fluency was calculated as the inverse of the average number of times a landmark velocity in the frontal plane crossed zero. Variability was defined as the standard deviation of the frontal plane movement trajectories. CoM fluency and displacement variability were significantly different between tasks (p < .001). CoM displacement variability was consistently smallest compared to the constituent landmarks (p < .005). This was interpreted as a whole body strategy of compensatory variability constraining CoM frontal plane movement. Ipsilateral knee fluency (p < .01) and displacement variability (p < .001) differed substantially between tasks. The role of the weight-bearing knee seemed dependent on task constraints of the overall movement and balance, as well as constraints specific for knee joint stability.


Assuntos
Fenômenos Biomecânicos/fisiologia , Terapia por Exercício , Joelho/fisiologia , Movimento/fisiologia , Equilíbrio Postural/fisiologia , Adulto , Feminino , Humanos , Masculino , Adulto Jovem
6.
Knee Surg Sports Traumatol Arthrosc ; 24(1): 279-86, 2016 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-25315084

RESUMO

PURPOSE: Single leg hop for distance is used to inform rehabilitation and return to sport following anterior cruciate ligament reconstruction. However, impairment of landing mechanics may persist after the recommended performance parameter (hop distance) has been met; therefore, alternative methods are required. This study follows the COSMIN guideline to investigate the measurement properties of data from a new instrument (2D TIP). This is a simple motion analysis instrument to assess landing strategy based on more complex biomechanical modelling. METHODS: Data collected in the clinical setting from 30 subjects with chronic ACL deficiency (mean 15.5, SD 4.3 months following injury) before and 6 months after ACL reconstruction and a healthy control group were analysed. Reliability and measurement error were calculated using two repeated measures from three independent raters. Construct validity was assessed by hypothesis testing, and known groups validity and responsiveness were defined by differences between groups. RESULTS: The data demonstrate excellent inter-rater (ICC = 0.81-1.00) and intra-rater (ICC = 0.85-1.00) reliability with low measurement error. Of the eight construct validity hypothesis, six were fully and two partially supported. Between-group differences were significant (P < 0.05) supporting the validity and responsiveness hypothesis. CONCLUSION: 2D TIP is a simple and inexpensive instrument for assessing landing strategy that has demonstrated appropriate reliability, validity and responsiveness in the ACL-injured population. The instrument will now be used to identify altered movement strategies and develop novel rehabilitation interventions that target strategy and performance. LEVEL OF EVIDENCE: Prospective diagnostic study, Level II.


Assuntos
Reconstrução do Ligamento Cruzado Anterior/reabilitação , Ligamento Cruzado Anterior/cirurgia , Técnicas de Diagnóstico por Cirurgia , Traumatismos do Joelho/diagnóstico , Traumatismos dos Tendões/diagnóstico , Adulto , Lesões do Ligamento Cruzado Anterior , Doença Crônica , Feminino , Humanos , Traumatismos do Joelho/cirurgia , Masculino , Modelos Biológicos , Estudos Prospectivos , Reprodutibilidade dos Testes , Volta ao Esporte , Traumatismos dos Tendões/cirurgia
7.
Knee ; 22(5): 360-71, 2015 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-26056046

RESUMO

OBJECTIVE: Treatment of knee conditions should include approaches to support self-care and exercise based interventions. The most effective way to combine self-care and exercise has however not been determined sufficiently. Therefore the aim was to evaluate the clinical effectiveness of self-care programmes with an exercise component for individuals with any type of knee conditions. METHODS: A keyword search of Medline, CINAHL, Amed, PsycInfo, Web of Science, and Cochrane databases was conducted up until January 2015. Two reviewers independently assessed manuscript eligibility against inclusion/exclusion criteria. Study quality was assessed using the Downs and Black quality assessment tool and the Cochrane Risk of Bias Tool. Data were extracted about self-care and exercise intervention type, control intervention, participants, length of follow-up, outcome measures, and main findings. RESULTS: From the 7392 studies identified through the keyword search the title and abstract of 5498 were screened. The full text manuscripts of 106 studies were retrieved to evaluate their eligibility. Twenty-one manuscripts met the inclusion/exclusion criteria. CONCLUSION: The treatment potential of combined self-care and exercise interventions has not been maximised because of limitations in study design and failure to adequately define intervention content. Potentially the most beneficial self-care treatment components are training self-management skills, information delivery, and goal setting. Exercise treatment components could be strengthened by better attention to dose and progression. Modern technology to streamline delivery and support self-care should be considered. More emphasis is required on using self-care and exercise programmes for chronic condition prevention in addition to chronic condition management.


Assuntos
Reconstrução do Ligamento Cruzado Anterior/reabilitação , Artralgia/terapia , Dor Crônica/terapia , Terapia por Exercício , Osteoartrite do Joelho/terapia , Autocuidado , Humanos
8.
J Neuroeng Rehabil ; 11: 19, 2014 Feb 28.
Artigo em Inglês | MEDLINE | ID: mdl-24581172

RESUMO

BACKGROUND: Anterior cruciate ligament (ACL) injured individuals often show asymmetries between the injured and non-injured leg. A better understanding of the underlying motor control could help to improve rehabilitation. Double leg squat exercises allow for compensation strategies. This study therefore investigated motor control strategies during a double leg squat with the aim to investigate if individuals with ACL rupture (ACLD), ACL reconstruction (ACLR) and healthy control subjects (CONT) used different strategies. METHODS: 20 ACLD and 21 ACLR were compared to 21 CONT subjects. Participants performed eight continuous double leg squats to their maximum depth, while kinematic and kinetic data were collected. Outcome measures were calculated to quantify the behavior of the injured and non-injured legs and the asymmetry between these legs. RESULTS: Squat depth was significantly reduced in ACLR and ACLD compared to CONT (p < 0.05; 106 ± 17°; 105 ± 21°; 113 ± 21°). Peak knee extensor moments (Mkn(mx)) were significantly reduced in ACLR and ACLD compared to CONT in the injured leg only (p < 0.05; 0.045 ± 0.015; 0.046 ± 0.016; 0.059 ± 0.022 body weight.height respectively). There was no significant correlation between symmetry of the support moment (SYM(Msup)) and of the % support moment by the knee (SYM%supkn) in CONT (R(2) = -0.07). Data distribution average indicated good symmetry. ACLR showed a significant correlation between SYM(Msup) and SYM%sup(kn) (R(2) = 0.561) when two participants who did not recover as well were excluded. ACLR controlled knee moment magnitude using two strategies; 1) transfer of support moment to non-injured leg; 2) transfer of support moment from knee to ankle and/or hip of injured leg. These were combined in different proportions, but with the same effect on the knee moment. ACLD showed no significant correlation between SYM(Msup) and SYM%sup(kn) (R(2) = 0.015). Data distribution average indicated reduced symmetry. ACLD therefore used an avoidance strategy: reducing squat depth and subsequently the support moment in the injured leg and the knee contribution. CONCLUSIONS: ACLD and ACLR individuals used different squatting strategies compared to controls, with ACLR using controlled and ACLD using avoidance behavior regarding knee loading. This has major implications for rehabilitation as these kinetic strategies cannot be observed, but result in the injured leg not being exercised as intended.


Assuntos
Reconstrução do Ligamento Cruzado Anterior/reabilitação , Exercício Físico/fisiologia , Atividade Motora/fisiologia , Força Muscular/fisiologia , Adulto , Fenômenos Biomecânicos , Feminino , Humanos , Perna (Membro) , Masculino
9.
Clin Biomech (Bristol, Avon) ; 29(2): 206-12, 2014 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-24447417

RESUMO

BACKGROUND: Functional exercises are important in the rehabilitation of anterior cruciate ligament deficient and reconstructed individuals but movement compensations and incomplete recovery persist. This study aimed to identify how tasks pose different challenges; and evaluate if different activities challenge patient groups differently compared to controls. METHODS: Motion and force data were collected during distance hop, squatting and gait for 20 anterior cruciate ligament deficient, 21 reconstructed and 21 controls. FINDINGS: Knee range of motion was greatest during squatting, intermediate during hopping and smallest during gait (P < 0.01). Peak internal knee extensor moments were greatest during distance hop (P < 0.01). The mean value of peak knee moments was reduced in squatting and gait (P < 0.01) compared to hop. Peak internal extensor moments were significantly larger during squatting than gait and peak external adductor moments during gait compared to squatting (P < 0.01). Fluency was highest during squatting (P < 0.01). All patients demonstrated good recovery of gait but anterior cruciate ligament deficient adopted a strategy of increased fluency (P < 0.01). During squatting knee range of motion and peak internal knee extensor moment were reduced in all patients (P < 0.01). Both anterior cruciate ligament groups hopped a shorter distance (P < 0.01) and had reduced knee range of motion (P < 0.025). Anterior cruciate ligament reconstructed had reduced fluency (P < 0.01). INTERPRETATION: Distance hop was most challenging; squatting and gait were of similar difficulty but challenged patients in different ways. Despite squatting being an early, less challenging exercise, numerous compensation strategies were identified, indicating that this may be more challenging than gait.


Assuntos
Lesões do Ligamento Cruzado Anterior , Reconstrução do Ligamento Cruzado Anterior/reabilitação , Traumatismos do Joelho/reabilitação , Articulação do Joelho/fisiopatologia , Amplitude de Movimento Articular/fisiologia , Adulto , Ligamento Cruzado Anterior/fisiopatologia , Fenômenos Biomecânicos , Estudos de Casos e Controles , Terapia por Exercício , Feminino , Marcha/fisiologia , Humanos , Traumatismos do Joelho/fisiopatologia , Masculino , Pessoa de Meia-Idade , Adulto Jovem
10.
J Biomech ; 47(3): 675-80, 2014 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-24342500

RESUMO

Anterior cruciate ligament (ACL) injury can result in failure to return to pre-injury activity levels and future osteoarthritis predisposition. Single leg hop is used in late rehabilitation to evaluate recovery and inform treatment but biomechanical understanding of this activity is insufficient. This study investigated single leg hop for distance aiming to evaluate if ACL patients had recovered: (1) landing strategies and (2) medio-lateral knee control. We hypothesized that patients with reconstructive surgery (ACLR) would have more similar landing strategies and knee control to healthy controls than patients treated conservatively (ACLD). 16 ACLD and 23 ACLR subjects were compared to 20 healthy controls (CONT). Kinematic and ground reaction force data were collected while subjects hopped their maximum distance. The main output parameters were hop distance, peak knee flexor angles and extensor moments and Fluency (a measure introduced to represent medio-lateral knee control). Statistical differences between ACL and control groups were analyzed using a general linear model univariate analysis, with COM velocity prior to landing as covariate. Hop distance was the smallest for ACLD and largest for CONT (p<0.001; ACLD 57.1±14.1; ACLR 75.1±17.8; CONT 77.7±14.07% height). ACLR used a similar kinematic strategy to CONT, but had a reduced peak knee extensor moment (p<0.001; ACLD 0.32±0.14; ACLR 0.31±0.16; CONT 0.42±0.13 BW.height). Fluency was reduced in both ACLD and ACLR (p=0.006; ACLD 0.13±0.34; ACLR 0.14±0.34; CONT 0.17±0.41s). Clinical practice uses hopping distance to evaluate ACL patients' recovery. This study demonstrated that aspects such as movement strategies and knee control need to be evaluated.


Assuntos
Lesões do Ligamento Cruzado Anterior , Ligamento Cruzado Anterior/fisiopatologia , Traumatismos do Joelho/fisiopatologia , Traumatismos do Joelho/reabilitação , Modalidades de Fisioterapia , Procedimentos de Cirurgia Plástica/reabilitação , Adulto , Idoso , Ligamento Cruzado Anterior/cirurgia , Fenômenos Biomecânicos/fisiologia , Avaliação da Deficiência , Feminino , Humanos , Humulus , Traumatismos do Joelho/cirurgia , Articulação do Joelho/fisiopatologia , Articulação do Joelho/cirurgia , Perna (Membro) , Masculino , Modelos Biológicos , Movimento/fisiologia , Osteoartrite do Joelho/prevenção & controle , Recuperação de Função Fisiológica/fisiologia , Adulto Jovem
11.
Hum Mov Sci ; 32(5): 984-96, 2013 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-24120280

RESUMO

Falls are common in older adults. The most common cause of falls is tripping while walking. Simulation studies demonstrated that older adults may be restricted by lower limb strength and movement speed to regain balance after a trip. This review examines how modeling approaches can be used to determine how different measures predict actual fall risk and what some of the causal mechanisms of fall risk are. Although increased gait variability predicts increased fall risk experimentally, it is not clear which variability measures could best be used, or what magnitude of change corresponded with increased fall risk. With a simulation study we showed that the increase in fall risk with a certain increase in gait variability was greatly influenced by the initial level of variability. Gait variability can therefore not easily be used to predict fall risk. We therefore explored other measures that may be related to fall risk and investigated the relationship between stability measures such as Floquet multipliers and local divergence exponents and actual fall risk in a dynamic walking model. We demonstrated that short-term local divergence exponents were a good early predictor for fall risk. Neuronal noise increases with age. It has however not been fully understood if increased neuronal noise would cause an increased fall risk. With our dynamic walking model we showed that increased neuronal noise caused increased fall risk. Although people who are at increased risk of falling reduce their walking speed it had been questioned whether this slower speed would actually cause a reduced fall risk. With our model we demonstrated that a reduced walking speed caused a reduction in fall risk. This may be due to the decreased kinematic variability as a result of the reduced signal-dependent noise of the smaller muscle forces that are required for slower. These insights may be used in the development of fall prevention programs in order to better identify those at increased risk of falling and to target those factors that influence fall risk most.


Assuntos
Acidentes por Quedas , Simulação por Computador , Marcha/fisiologia , Força Muscular/fisiologia , Equilíbrio Postural/fisiologia , Caminhada/fisiologia , Aceleração , Acidentes por Quedas/prevenção & controle , Fatores Etários , Idoso , Fenômenos Biomecânicos/fisiologia , Humanos , Postura/fisiologia , Medição de Risco
12.
J Biomech ; 46(10): 1722-8, 2013 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-23659911

RESUMO

Older adults and those with increased fall risk tend to walk slower. They may do this voluntarily to reduce their fall risk. However, both slower and faster walking speeds can predict increased risk of different types of falls. The mechanisms that contribute to fall risk across speeds are not well known. Faster walking requires greater forward propulsion, generated by larger muscle forces. However, greater muscle activation induces increased signal-dependent neuromuscular noise. These speed-related increases in neuromuscular noise may contribute to the increased fall risk observed at faster walking speeds. Using a 3D dynamic walking model, we systematically varied walking speed without and with physiologically-appropriate neuromuscular noise. We quantified how actual fall risk changed with gait speed, how neuromuscular noise affected speed-related changes in fall risk, and how well orbital and local dynamic stability measures predicted changes in fall risk across speeds. When we included physiologically-appropriate noise to the 'push-off' force in our model, fall risk increased with increasing walking speed. Changes in kinematic variability, orbital, and local dynamic stability did not predict these speed-related changes in fall risk. Thus, the increased neuromuscular variability that results from increased signal-dependent noise that is necessitated by the greater muscular force requirements of faster walking may contribute to the increased fall risk observed at faster walking speeds. The lower fall risk observed at slower speeds supports experimental evidence that slowing down can be an effective strategy to reduce fall risk. This may help explain the slower walking speeds observed in older adults and others.


Assuntos
Acidentes por Quedas , Modelos Biológicos , Músculo Esquelético/fisiologia , Caminhada/fisiologia , Fenômenos Biomecânicos , Simulação por Computador , Marcha/fisiologia , Humanos , Risco
13.
J Biomech ; 45(9): 1656-60, 2012 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-22503882

RESUMO

Patellofemoral pain (PFP) is a common injury and increased patellofemoral joint compression forces (PFJCF) may aggravate symptoms. Backward running (BR) has been suggested for exercise with reduced PFJCF. The aims of this study were to (1) investigate if BR had reduced peak PFJCF compared to forward running (FR) at the same speed, and (2) if PFJCF was reduced in BR, to investigate which biomechanical parameters explained this. It was hypothesized that (1) PFJCF would be lower in BR, and (2) that this would coincide with a reduced peak knee moment caused by altered ground reaction forces (GRFs). Twenty healthy subjects ran in forward and backward directions at consistent speed. Kinematic and ground reaction force data were collected; inverse dynamic and PFJCF analyses were performed. PFJCF were higher in FR than BR (4.5±1.5; 3.4±1.4BW; p<0.01). The majority of this difference (93.1%) was predicted by increased knee moments in FR compared to BR (157±54; 124±51 Nm; p<0.01). 54.8% of differences in knee moments could be predicted by the magnitude of the GRF (2.3±0.3; 2.4±0.2BW), knee flexion angle (44±6; 41±7) and center of pressure location on the foot (25±11; 12±6%) at time of peak knee moment. Results were not consistent in all subjects. It was concluded that BR had reduced PFJCF compared to FR. This was caused by an increased knee moment, due to differences in magnitude and location of the GRF vector relative to the knee. BR can therefore be used to exercise with decreased PFJCF.


Assuntos
Articulação Patelofemoral/fisiologia , Corrida/fisiologia , Adulto , Fenômenos Biomecânicos , Feminino , Humanos , Masculino , Estresse Mecânico , Adulto Jovem
14.
J Biomech ; 44(8): 1514-20, 2011 May 17.
Artigo em Inglês | MEDLINE | ID: mdl-21440895

RESUMO

Measures that can predict risk of falling are essential for enrollment of older adults into fall prevention programs. Local and orbital stability directly quantify responses to very small perturbations and are therefore putative candidates for predicting fall risk. However, research to date is not conclusive on whether and how these measures relate to fall risk. Testing this empirically would be time consuming or may require high risk tripping experiments. Simulation studies therefore provide an important tool to initially explore potential measures to predict fall risk. This study performed simulations with a 3D dynamic walking model to explore if and how dynamic stability measures predict fall risk. The model incorporated a lateral step controller to maintain lateral stability. Neuronal noise of increasing amplitude was added to this controller to manipulate fall risk. Short-term (λ(S)(*)) local instability did predict fall risk, but long-term (λ(L)(*)) local instability and orbital stability (maxFM) did not. Additionally, λ(S)(*) was an early predictor for fall risk as it started increasing before fall risk increased. Therefore, λ(S)(*) could be a very useful tool to identify older adults whose fall risk is about to increase, so they can be enrolled in fall prevention programs before they actually fall.


Assuntos
Marcha/fisiologia , Imageamento Tridimensional/métodos , Caminhada/fisiologia , Acidentes por Quedas/prevenção & controle , Idoso , Fenômenos Biomecânicos , Simulação por Computador , Desenho de Equipamento , Humanos , Modelos Biológicos , Neurônios/patologia , Equilíbrio Postural
15.
J Biomech ; 43(15): 2929-35, 2010 Nov 16.
Artigo em Inglês | MEDLINE | ID: mdl-20708189

RESUMO

People at risk of falling exhibit increased gait variability, which may predict future falls. However, the causal mechanisms underlying these correlations are not well known. Increased neuronal noise associated with aging likely leads to increased gait variability, which could in turn lead to increased fall risk. This paper presents a model of how changes in neuromuscular noise independently affect gait variability and probability of falling, and aims to determine the extent to which changes in gait variability directly predict fall risk. We used a dynamic walking model that incorporates a lateral step controller to maintain lateral stability. Noise was applied to this controller to approximate neuromuscular noise in humans. Noise amplitude was varied between low amplitudes that did not induce falls and high amplitudes for which the model always fell. With increases in noise amplitude, the model fell more often and after fewer steps. Gait variability increased with noise amplitude and predicted increased probability of falling. Importantly, these relationships were not linear. At either low gait variability or very high gait variability, small increases in noise and variability affected probability of falling very little. Conversely, at intermediate noise and/or variability levels, the same small increases resulted in large increases in probability of falling. Our results validate the idea that age-related increases in neuromuscular noise likely play a direct contributing role in increasing fall risk. However, neuromuscular noise remains only one of many important factors that need to be considered. These findings have important implications for fall prevention research and practice.


Assuntos
Acidentes por Quedas , Modelos Biológicos , Caminhada/fisiologia , Acidentes por Quedas/prevenção & controle , Idoso , Envelhecimento/fisiologia , Fenômenos Biomecânicos , Marcha/fisiologia , Humanos , Junção Neuromuscular/fisiologia , Fatores de Risco
16.
Clin Biomech (Bristol, Avon) ; 25(9): 873-8, 2010 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-20667634

RESUMO

BACKGROUND: Fall occurrence, mainly due to tripping, increases with age. There are two main strategies of trip recovery: elevating and lowering. Strategy selection depends on trip stimulus timing within the swing phase of walking, but the choice and ultimate success of a strategy selection may also depend on individual physical characteristics. The aim of this study was to investigate: 1) recovery strategy choice by younger and older adults when perturbed in the 'strategy overlap' mid-swing phase, and 2) whether the interaction between recovery limb positioning and recovery limb force capacity determines recovery success in elevating strategy recoveries and accounts for strategy selection. METHODS: A group of older (65-75 years) and a group of younger adults (20-35 years) completed a trip recovery protocol in a laboratory environment. An inverted pendulum model was developed to investigate how walking speed, recovery limb positioning and recovery limb force interacted and influenced successful trip recovery when perturbed in different swing phases. FINDINGS: Older adults always adopted a lowering strategy when perturbed in late mid-swing (60-80%), while younger adults also adopted elevating strategies. Simulations showed that, when perturbed later in swing, a larger recovery step and higher recovery limb force were required for successful recovery. INTERPRETATION: We suggested that a combination of insufficient recovery limb strength, response time and movement speed make it difficult for older adults to achieve a large enough recovery step for a successful elevating strategy recovery when perturbed later in mid-swing.


Assuntos
Envelhecimento , Extremidades/fisiologia , Marcha/fisiologia , Caminhada/fisiologia , Acidentes por Quedas/prevenção & controle , Adulto , Idoso , Fenômenos Biomecânicos , Simulação por Computador , Humanos , Equilíbrio Postural , Fatores de Tempo
17.
Gait Posture ; 27(2): 352-6, 2008 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-17561398

RESUMO

The aims of this study were to investigate which arm movements are made during trip recovery, to determine the contributions of arm movements in trip recovery and to identify differences in these contributions between younger and older adults and different recovery strategies. A group of seven older adults (65-75 years) and a group of eight younger adults (20-35 years) were examined. Participants completed a trip recovery protocol in which 3-D kinematic and kinetic data were collected for recovery movements following unexpected trips during locomotion. In younger adults, arm movements were associated with an elevated body centre of mass (CM) position during recovery. Arm movements also served to reduce the angular momentum in the direction of the trip by 13% between trip stimulus and recovery foot contact in 'elevating' recovery strategies. Arm movements in older adults contributed an additional 3% to the destabilising angular momentum during 'elevating' recoveries. It was concluded that older adults exhibit a more 'protective' recovery strategy (to limit injury resulting from fall impacts following loss of balance) and younger adults exhibit a more 'preventive' strategy (to prevent loss of balance).


Assuntos
Acidentes por Quedas , Envelhecimento/fisiologia , Braço/fisiologia , Movimento , Acidentes por Quedas/prevenção & controle , Adulto , Idoso , Antropometria , Fenômenos Biomecânicos , Feminino , Humanos , Fatores de Risco , Inquéritos e Questionários
18.
J Biomech ; 37(11): 1655-63, 2004 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-15388307

RESUMO

The measurement of drag while swimming (i.e. active drag) is a controversial issue. Therefore, in a group of six elite swimmers two active drag measurement methods were compared to assess whether both measure the same retarding force during swimming. In method 1 push-off forces are measured directly using the system to measure active drag (MAD-system). In method 2 (the velocity perturbation method, VPM) drag is estimated from the difference in swimming speed when subjects swim twice at maximal effort (assuming equal power output and assuming a quadratic drag-speed relationship): once swimming free, and once swimming with a hydrodynamic body attached that created a known additional resistance. The average drag for the VPM tests (53.2 N) was statistically significant and different from the active drag for the MAD-test (66.9 N), paired Student's t-test: 2.484, 12 DF, p=0.029. A post hoc analysis was performed to assess whether the two methods measure a different phenomenon. Based on the drag speed curve obtained with the MAD-system, the VPM-data were re-examined. For diverging drag determinations the assumption of equal power output of the 'free' trial (swimming free) vs. the towing trial (swimming with hydrodynamic buoy) appeared to be violated. The regression of the relative difference in force (MAD vs. VPM) on the relative difference in power (swimming free vs. swimming with hydrodynamic body) was: %Deltadrag=1.898 x %Deltapower -4.498, r2=0.88. This suggests that the major part of the difference in active drag values is due to a non-equal power output in the 'free' relative towing trial during the VPM-test. The simulation of the violation of the equal power output assumption and the calculation of the effect of an other than quadratic drag-speed relationship corroborated the tentative conclusion that both methods measure essentially the same phenomenon and that active drag differences can be explained by a violation of test assumptions.


Assuntos
Natação/fisiologia , Adolescente , Adulto , Fenômenos Biomecânicos , Feminino , Humanos , Masculino
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