A concussion can result in a wide range of signs and symptoms including physical, cognitive, emotional and sleep-related symptoms. While a concussion can occur at any age, children and adolescents are at an increased risk of experiencing a concussion. Important physical consequences of concussion are balance deficits which affect approximately one in three cases. Balance is essential to perform many postures and activities and therefore it is important to accurately identify these deficits at the time of injury and during the recovery process in order to avoid potential further injury. A review of the literature regarding the different clinical and laboratory measures used to assess balance following a concussion was completed and identified several gaps in the literature. The four studies in this thesis were tailored to address these gaps in knowledge. The first study addressed the sensitivity of a gold standard clinical measure and laboratory measures of standing balance in terms of identifying balance deficits in adolescents at 1-month post-concussion. Performance on the Balance Error Scoring System (BESS) and COP measures from single and dual-task balance conditions were compared between a group of adolescents at one-month post-concussion and a group of non-injured adolescents. The results demonstrated that COP measures from single and dual-task conditions identified balance deficits in the concussed group that were not captured by the BESS. The second study addressed whether self-reported balance problems are a suitable alternative to COP measures to identify balance deficits in concussed adolescents. A secondary analysis of the data from study 1 was conducted to compare COP measures from the single and dual-task conditions between concussed adolescents self-reporting balance problems, concussed adolescents self-reporting no balance problems and a group of non-injured adolescents. The results from this analysis showed that the concussed adolescents demonstrated balance deficits regardless of whether they self-reported balance problems. There is significant clinical interest that lies in the ability to predict which adolescents presenting in the emergency department with concussion will be affected with ongoing balance deficits. The third study addressed the predictive ability of a set of COP variables recorded within the first 10 days following injury in a group of concussed adolescents to predict balance performance on a dual-task condition at one-month post-injury. Seven COP variables were identified as significant predictors. A secondary objective of this study was to compare performance on the COP measures between the concussed adolescents and a group of non-injured adolescents during the first session within the first 10 days following injury and during the second session at one-month post-injury and to compare performance between sessions within each group. The between session comparisons showed that performance remained relatively stable across sessions within both groups. In contrast, the between group comparisons revealed several significant differences in COP measures between the concussed and non-injured groups. The fourth study in this thesis addressed the association between balance and saccadic eye movements in concussed adolescents. Impaired saccadic eye movements are an important consequence of concussion and may be associated with balance deficits since both processes are dependent on several of the same cortical structures and brainstem areas. In this study, concussed and non-injured adolescents performed three different dual-task balance conditions involving either a high cognitive load, a low cognitive load and a gaze shifting component or a high cognitive load and a gaze shifting component. The results demonstrated that the concussed adolescents swayed over larger 95% ellipse areas while performing the two dual-tasks with the gaze shifting component, but these larger amounts of sway were not associated with an increase in saccades. Taken together, these four studies extend the current knowledge regarding balance performance in concussed adolescents and provide results that can be applied to balance assessments for concussion.

This research studies the electrical power reduction and control analysis of various motion tasks of a humanoid robot. These motions include standing up and sitting down. Each motion’s tasks have their stable and unstable phases throughout the complete motion cycle. Unstable phases can be caused by gravity forces and improper handling of the upper body of the humanoid robot leaning too forward or backward. Even though most of the dynamic motions seem to be accomplished very simply by humans; standing up and sitting down could create challenges for humanoid robots. Some of the critical challenges researches face are: dynamic nature of motions, humanoid robot joint coordination, whole body balance, stability of the model, limited energy source, energy saving techniques and modeling. Dynamic motions of humanoid robots can be modeled and analyzed to reduce electrical power use. In order to accomplish such energy savings, a researcher needs to study the kinematics, dynamics of a humanoid, and motion tasks with given constraints. The robot in this research is modeled as a planar humanoid robot. All motion tasks of a humanoid robot are characterized in terms of motion variables. These motion variables include joint angular positions, joint angular velocity, joint angular acceleration, humanoid robot center of mass (CoM) position, velocity and acceleration change and center of pressure (CoP) position change. All mathematical models are completed so that electrical power analysis of each task produce comparable results. Humanoid robot joint cost functions related to energy consumption are used to define joint input electrical power used, joint mechanical power used, joint mechanical power dispersion and joint power loss due to torque required. In this research, a 4-link 3-joint humanoid is modeled for standing up and sitting down tasks. For each task, kinematics and dynamics models are created, motion constraints are found, energy and power usage analysis for whole robot and for individual joint motors are accomplished. By finding the best energy usage per motion variable, humanoid robot used less input electrical power to accomplish the motion task.

INTRODUCTION: Cerebral Palsy (CP) is the most common disabling motor disorder found during childhood, occurring in 2.1-3.2 of every 1,000 births. Motor functionality of children with CP is commonly compromised and is classified with a gross motor function classification score (GMFCS) and with the gross motor function measure (GMFM). Balance ability has typically been assessed using single leg stance test (SLST) time but more recently, center of pressure excursion (COPE) has shown to be a more valid measurement in populations with altered motor abilities. However, COPE has not been used to test balance in the CP population, yet. This study aimed to determine if relationships were present between COPE measurements, functionality measurement scores (GMCS and GMFM) and reported fall frequency. It was hypothesized that i) larger COPE measurements would be associated with a higher GMFCS level and lower GMFM score, and that ii) COPE measurements would be significantly higher in children with a high reported incidence of fall frequency. METHODS: Gross functionality was measured using a GMFM score and GMFCS level. Balance ability was assessed using COPE measurements on a force plate and SLST time. Fall frequency was determined by a short questionnaire. A Pearson correlation analyzed COPE measurements vs. mean GMFM score. A one-way ANOVA was used to compare COPE measures between GMFMCS levels, with a Bonferroni post-hoc test. Lastly, an independent sample t-test analyzed differences in COPE measurements and SLST time between fall frequency groups. RESULTS: Significantly larger COPE velocities were demonstrated in children who reported a greater number of falls in the past month and were considered high risk for falling (p = 0.02). No relationships were demonstrated between COPE measurements and GMFM score. GMFCS level III participants demonstrated statistically significant lower COPE velocity compared to GMFCS level II participants (p = 0.05). There were no significant differences in SLST between high and low risk fall groups (p = 0.07). DISCUSSION: Children with higher reported fall frequencies demonstrated a 60% increase in COPE velocity, compared to those with little to no falls. Clinical GMFM scores did not demonstrate significant correlations to COPE measurements and may not be an appropriate identifier for falling in children diagnosed with CP. This is the first trial to evaluate COPE measurements and reported fall frequencies in children diagnosed with CP. The use of a force plate to determine COPE velocity during a SLST is useful in identifying children with CP who may be at an elevated risk for experiencing a fall. COPE velocity was able to provide intricate quantitative data regarding fall risk that could not be obtained during a normal SLST.

No description available.

BAKGRUND: Personer med amputation på transhumeral nivå har en asymmetrisk anatomi. Det är inte väl studerat hur denna asymmetri påverkar dessa personers stående och gång, och inte heller vilka besvär som detta skulle kunna orsaka. SYFTE: Att undersöka om någon skillnad i stillastående kropps-hållning och gångmönster uppstår då personer med transhumeral amputation använder respektive inte använder protes. Utöver det så är också syftet att undersöka om ryggbesvär förekommer hos personer med denna amputationsnivå. METOD: Två transhumeralt amputerade personer deltog i studien. Statisk undersökning och gånganalys genomfördes med och utan armprotes. En enkätundersökning gällande muskuloskeletala besvär genomfördes på deltagarna. RESULTAT: Inga större skillnader har hittats i bäckenets kinematik och bålens rörelse i sagittalplan då försökspersonerna går utan protes jämfört med när de går med protes. Däremot har vi funnit en thorakal lateralflexion mot den amputerade sidan under gång, som minskar då försökspersonerna använder protes. Då försökspersonerna är stillastående utan protes lutar de mot den amputerade sidan. När de använder protes minskar lutningen. Försökspersonerna led inte av ryggbesvär. SLUTSATS: Användande av armprotes för personer med transhumeral amputation verkar ge en rakare hållning under gång och stående. / BACKGROUND: People with transhumeral amputation have an asymmetrical anatomy. The influence of this asymmetry on gait and standing has not been well studied, neither has the potential problems that this could cause. OBJECTIVE: To investigate if any difference in standing posture and gait kinematics occur when people with transhumeral amputation use a prosthesis compared to when they don’t. Furthermore, the aim is to investigate if back problems are prevalent among people with this amputation level. METHODS: Two transhumeral amputees participated in this study. Static and gait analysis was conducted with and without prosthesis. The participants completed a survey regarding musculoskeletal problems. RESULTS: No major difference has been found in thorax tilt and pelvic kinematics when the subjects walk with compared to without prosthesis. However we have found a thorax obliquity towards the amputated side during walking, which is reduced when the subjects use their prosthesis. The subjects are leaning towards the amputated side when standing without prosthesis. When using the prosthesis the obliquity is reduced. The subjects do not suffer from any back problems. CONCLUSIONS: Use of an arm prosthesis seems to give people with transhumeral amputation a more upright posture during walking and standing.

Introduction: It has been proposed that inadequate rest intervals may contribute to decreased performance of activities. However, previous research has not investigated the effect of rest interval on performance of the Star Excursion Balance Test (SEBT) in individuals with and without chronic ankle instability. Objective: To determine whether rest interval affects performance of the SEBT associated with chronic ankle instability (CAI) and whether neuromuscular function, postural control or biomechanics can be associated factors which may help discriminate between healthy individuals and those with CAI during the SEBT. Design: 2-group counterbalanced study. Participants: Participants included 24 individuals with a history of at least one ankle sprain in the past year and at least 2 episodes of giving way in the past 6 month prior to study enrollment, and 24 individuals with no history of ankle sprain or instability in their lifetime. Methods: Subjects completed 3 trials in each of the 3 reach directions (anteromedial, medial, posteromedial) in random order. A total of three visits were required in order to complete the 3 rest intervals (10, 20, 40 seconds). Normalized maximum reach distance, electromyographic (EMG) activation of tibialis anterior, peroneus longus, and medial gastrocnemius muscles, multiplanar motion of the lower extremity, coupling angles (CA) of lower extremity segments and maximum lateral center of pressure velocity were calculated and compared between groups in each direction for each rest interval. Results: Rest interval did not influence differences of reach distance, EMG ankle muscle activation, kinematics and center of pressure velocity between healthy individuals and those with CAI during the SEBT. However, the rest interval of 20 seconds demonstrated differences in CAs of tibial internal rotation/dorsiflexion (TIR/DF) and tibial internal rotation/eversion (TIR/EV) between healthy individuals and those with CAI during the SEBT. Overall, reach distance, mean amplitude of EMG ankle muscles, kinematics and joint CAs were different between healthy individuals and those with CAI during the SEBT regardless of rest interval. Discussion: Based on these results, differences exist in neuromuscular functions and biomechanics between healthy individuals and those with CAI when performing the SEBT. A rest interval time of 20 seconds between trials during the SEBT is an appropriate time to discriminate joint CAs of TIR/DF and TIR/EV between healthy individuals and those with CAI during the SEBT. These findings have implications for treatment and possible prevention of CAI.

A escoliose idiopática do adolescente (EIA) é uma deformidade da coluna vertebral que acomete indivíduos entre 10 e 19 anos de idade, caracteriza-se por desvios das curvas nos planos frontal e sagital, e rotação intervertebral no plano axial. Devido a sua natureza tridimensional apresenta alterações biomecânicas que geram adaptações em músculos e ligamentos da coluna vertebral, alterando suas funções no controle postural. O tratamento cirúrgico visa corrigir os desvios e manter as curvas no plano sagital, através de artrodeses. Com base nesses conceitos, o objetivo do estudo foi avaliar a influência da escoliose idiopática do adolescente, e da sua correção cirúrgica, sobre o equilíbrio semi-estático. Participaram do estudo 30 adolescentes divididas em dois grupos: Grupo Controle (GC) [n=15], idade média de 15,13 ± 1,59 anos, massa corporal de 51,22 ± 2,5Kg e estatura de 159 ± 3cm, e Grupo Escoliose (GE) [n=15] com média de idade de 15 ± 1,64 anos, massa corporal de 46,1 ± 3,26Kg e estatura de 156 ± 3cm; das quais foi mesurada a oscilação do centro de pressão a partir de uma plataforma de força avaliando as variáveis: desvio ântero-posterior (DAP); desvio médio-lateral (DML); velocidade ântero-posterior (VAP); velocidade médio-lateral (VML) e área (A²). O GC realizou a avaliação do equilíbrio semi-estático em um único momento, enquanto o GE realizou a avaliação do equilíbrio semi-estático no momento pré-operatório (PRÉ) e no 7°, 30°, 60° e 90° dia de pós-operatório (PO). Foi avaliado o grau de correção da curvatura e a relação entre número de vértebras artrodesadas e a oscilação corporal. O equilíbrio semi-estático foi avaliado nas 4 posições de Romberg (P1 - pés separados, P2 - pés unidos, P3 - série parcial e P4 - série completa) nas condições olhos abertos (AO) e olhos fechado (OF). Os resultados mostram que o GE apresentou uma redução média de 49,8° para a curva torácica e 18,14° para as lombares. O número de vértebras artrodesadas foi de 11,26 ± 1,7. O GE apresentou maior oscilação que o GC, com diferença significativa nas quatro variáveis estudadas (DAP, DML, VAP, VML e A²) e em todas as posições/condições. Com base nos resultados verificou-se que o GE oscila mais que o GC tanto no pré-operatório como nos momentos pós-operatório. Na comparação entre as posições, GE oscilou mais no sentido AP em P1 e no sentido ML em P4, também obteve maior valor para a A². Para a VAP P2 foi a mais desafiadora e para VML foi P4. Os dados apontam para uma diminuição gradativa da oscilação com o passar dos dias de PO, porém no 90° dia o GE ainda apresenta valores superiores ao momento PRÉ. Portanto, os resultados mostram que a escoliose afeta o controle postural e que no 90° dia pós-cirúrgico a oscilação postural ainda se apresenta superior ao período pré-operatório, e que pode estar associado a um comprometimento sensório-motor ou a um problema de integração sensorial pré-existente, também relacionado as alterações biomecânicas decorrentes da cirurgia e seu efeito agudo. / The adolescent idiopathic scoliosis (AIS) is a spinal deformity that affects individuals between 10 and 19 years of age, characterized by deviations of the curves in the frontal and sagittal planes, and intervertebral rotation in the axial plane. Due to its three-dimensional nature presents biomechanical changes that cause changes in muscles and ligaments of the spinal column, altering their functions in postural control. Surgical treatment aims to correct the deviations and maintain the curves in the sagittal plane through arthrodesis. Based on these concepts, the study aimed to evaluate the influence of adolescent idiopathic scoliosis and its surgical correction on the semi-static balance. The study included 30 adolescents divided into two groups: control group (CG) [n = 15], mean age 15.13 ± 1.59 years, body mass 51.22 ± 2.5kg and height 159 ± 3cm, and scoliotic group (SG) [n = 15] mean age 15 ± 1.64 years, body mass index of 46.1 ± 3.26kg and height 156 ± 3cm, which was gauged from the oscillation the center of pressure from a force platform to evaluate the variables: anteroposterior deviation (APD); average-lateral devitation (MLD); anteroposterior speed (APS); average-lateral speed (MLS) and area (A²). CG carried out the assessment of the semi-static balance in a single moment, while the SG was evaluated at the preoperative period (PRE) and at the 7th, 30th, 60th and 90th days post operative (PO). We assessed the degree of curvature correction and the relationship between number of vertebrae arthrodesed and body sway. The static balance was assessed in 4 Romberg\'s positions (P1 - feet apart, P2 - feet together, P3 - partial series P4 and - full series) in eyes open conditions (EO) and eyes closed (EC). The results show that the SG had an average reduction of 49.8 degrees for the thoracic curve and 18.14 degrees for the lumbar. The number of vertebrae arthrodesed was 11.26 ± 1.7. The SG showed greater sway than the CG, with a significant difference in the four variables (APD; MLD; APS; MLS and A²) and in all positions/conditions. Based on the results it was found that the SG oscillates more than the CG (preoperatively and postoperatively). Comparing the positions of the SG volunteers ranged more towards AP in P1 and P4 in the ML direction, which also had higher values for the A². For the APS P2 was the most challenging and MLS was P4. The data indicate a gradual decrease of the oscillation over the postoperative days, but in the 90th day the GE still has higher values when the PRE. Therefore, the results show that scoliosis affects postural control and at the 90th day after the surgery the postural oscillation still superior tham postsurgery period, and maybe it can be associated with an impaired sensorimotor or a sensory integration problem pre-existing, related to the biomechanical changes followed from the surgery and its acute effect.

O objetivo deste estudo foi investigar o efeito do erro na localização do centro de pressão (5 e 10 mm) nas incertezas de momentos articulares dos membros inferiores em diferentes velocidades de marcha (1,0, 1,5 e 2,0 m/s). Nossas hipóteses foram que: as incertezas absolutas de momento articular diminuam de distal para o proximal e da condição de maior para a de menor velocidade. Os momentos articulares de cinco adultos jovens saudáveis foram calculados pelo método bottom-up de dinâmica inversa 3D, na dependência do qual estimamos as incertezas propagadas. Os resultados indicaram que existe uma relação diretamente proporcional entre os erros do centro de pressão e as incertezas de momento articular. As incertezas absolutas nos picos de momento expressas no sistema de referência anatômico diminuíram de distal para proximal, confirmando nossa primeira hipótese, exceto para o momento de abdução. Da menor para a maior velocidade de marcha ocorreu um aumento da incerteza no momento (de até 0,04 Nm/kg), confirmando agora nossa segunda hipótese, exceto, mais uma vez, para abduções de joelho e quadril. E ainda, as incertezas relativas variaram dependendo do plano e articulação (entre 5 e 31%), sendo os momentos articulares de joelho os mais afetados / The aim of this study was to investigate the effect of errors in the location of the center of pressure (5 and 10 mm) on lower limb joint moment uncertainties at different gait velocities (1.0, 1.5, and 2.0 m/s). Our hypotheses were that the absolute joint moment uncertainties would be gradually reduced from distal to proximal joints and from higher to lower velocities. Joint moments of five healthy young adults were calculated by inverse dynamics using the bottom-up approach, depending on which estimate the uncertainty propagated. Results indicated that there is a linear relationship between errors in center of pressure and joint moment uncertainties. The absolute moment peak uncertainties expressed on the anatomic reference frames decreased from distal to proximal joints, confirming our first hypothesis, except for the abduction moments. There was an increase in moment uncertainty (up to 0.04 Nm/kg for the 10 mm error in the center of pressure) from the lower to higher gait velocity, confirming our second hypothesis, although, once again, not for hip or knee abduction. Finally, depending on the plane of movement and the joint, relative uncertainties experienced variation (between 5 and 31%), and the knee joint moments were the most affected

O objetivo deste estudo foi investigar o efeito do erro na localização do centro de pressão (5 e 10 mm) nas incertezas de momentos articulares dos membros inferiores em diferentes velocidades de marcha (1,0, 1,5 e 2,0 m/s). Nossas hipóteses foram que: as incertezas absolutas de momento articular diminuam de distal para o proximal e da condição de maior para a de menor velocidade. Os momentos articulares de cinco adultos jovens saudáveis foram calculados pelo método bottom-up de dinâmica inversa 3D, na dependência do qual estimamos as incertezas propagadas. Os resultados indicaram que existe uma relação diretamente proporcional entre os erros do centro de pressão e as incertezas de momento articular. As incertezas absolutas nos picos de momento expressas no sistema de referência anatômico diminuíram de distal para proximal, confirmando nossa primeira hipótese, exceto para o momento de abdução. Da menor para a maior velocidade de marcha ocorreu um aumento da incerteza no momento (de até 0,04 Nm/kg), confirmando agora nossa segunda hipótese, exceto, mais uma vez, para abduções de joelho e quadril. E ainda, as incertezas relativas variaram dependendo do plano e articulação (entre 5 e 31%), sendo os momentos articulares de joelho os mais afetados / The aim of this study was to investigate the effect of errors in the location of the center of pressure (5 and 10 mm) on lower limb joint moment uncertainties at different gait velocities (1.0, 1.5, and 2.0 m/s). Our hypotheses were that the absolute joint moment uncertainties would be gradually reduced from distal to proximal joints and from higher to lower velocities. Joint moments of five healthy young adults were calculated by inverse dynamics using the bottom-up approach, depending on which estimate the uncertainty propagated. Results indicated that there is a linear relationship between errors in center of pressure and joint moment uncertainties. The absolute moment peak uncertainties expressed on the anatomic reference frames decreased from distal to proximal joints, confirming our first hypothesis, except for the abduction moments. There was an increase in moment uncertainty (up to 0.04 Nm/kg for the 10 mm error in the center of pressure) from the lower to higher gait velocity, confirming our second hypothesis, although, once again, not for hip or knee abduction. Finally, depending on the plane of movement and the joint, relative uncertainties experienced variation (between 5 and 31%), and the knee joint moments were the most affected

No description available.