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A research report submitted to the Faculty of Health Sciences, University of the Witwatersrand, in partial fulfilment of the requirements for the degree of Master of Science in Medicine in the field of Sports Science 15 May 2014 / Introduction: This study sought to determine the relationships between eccentric strength and power of the lower extremity with dynamic balance in male football players. Footballers with superior balance, kick more accurately, have a possible reduced risk of injury and faster agility times. However, the relationship between eccentric strength and power with dynamic balance remains unresolved. Methods: Fifty male footballers (university; n = 27 and professional; n = 23) volunteered to participate in the study and performed the Y-balance Test, eccentric isokinetic knee extensor and flexor testing and the countermovement jump. Results: The university group demonstrated significant positive correlations between mean eccentric peak torque to body weight of the knee extensors and composite score in the Ybalance test (r = 0.42, p = 0.03) and between eccentric peak torque to body weight of the knee extensors of the non-dominant leg with normalised reach distance in the Y-balance test on the non-dominant limb (r = 0.50, p = 0.008). In the professional group, countermovement jump height was significantly correlated with composite score in the Y-balance test (r = 0.52, p = 0.02). Furthermore, countermovement height was positively correlated to normalised reach distance in the Y-balance test on the non-dominant limb in the university (r = 0.4, p = 0.05) and professional (r = 0.56, p = 0.006) groups, respectively. Conclusion: Moderate positive relationships exist between eccentric strength of the knee extensors and dynamic balance in the university group and between power and dynamic balance in the professional group. These findings may be due to different coordination strategies between the groups to maximize reach distance. Both groups demonstrated a significant relationship between countermovement jump height and reach performance on the non-dominant leg. In footballers, different neural control strategies may develop between the limbs due to their constant use of their non-dominant leg to stabilise whilst executing a kicking action. Due to these significant relationships, a longitudinal study measuring the effects of strength and power training on dynamic balance in footballers is required to ascertain cause and effect.

A postura bípede reduz a área de apoio e demanda a atuação de um sistema de controle para manter o equilíbrio e a orientação dos segmentos corpóreos. A avaliação postural é muito importante nas intervenções fisioterapêuticas e a busca de sistemas confiáveis para avaliar a postura tem sido uma constante dentro da área. Nesta linha, a avaliação do equilíbrio sagital dado pela relação entre coluna lombar e pelve e pelo ângulo de incidência pélvica (IPE) tem sido usado para as alterações da coluna vertebral. Objetivo: fazer a mensuração dos parâmetros posturais pelo programa de avaliação postural (SAPO) e do equilíbrio sagital pelo programa Keops e fazer a correlação entre eles. Metodologia: foram avaliados 80 indivíduos saudáveis de ambos os sexos com idade entre 20 e 35 anos. Foi feita a biofotogrametria (marcação dos pontos anatômicos do indivíduo e fotografias com os marcadores) do programa SAPO. Foram utilizadas as variáveis obtidas nas vistas lateral esquerda e direita. As medidas dos parâmetros do equilíbrio sagital (ângulo de incidência pélvica é o mais relevante) foram obtidas pela análise de uma radiografia panorâmica em perfil da coluna vertebral, na qual se fazia a marcação digital de pontos anatômicos de referência. O cálculo dos ângulos era feito de forma automática pelo programa Keops. Resultados: pela avaliação do programa Keops: 17,5% dos indivíduos tinham ângulos de incidência pélvica altos ( > 60o), 51,2% tinham ângulos incidência pélvica médios (46-59o) e 31,5% tinham ângulos de incidência pélvica baixos ( < 45o). O SAPO mostrou 12,5% de lordose, 40% de retificação e 47,5% com curvatura normal. Na vista lateral direita, o ângulo de incidência pélvica teve correlação moderada e positiva com o alinhamento vertical do tronco e com o alinhamento vertical do corpo e negativa e moderada com o alinhamento horizontal da pelve. Na vista lateral esquerda o ângulo de incidência pélvica teve correlação fraca e negativa com o alinhamento horizontal da pelve. Não houve correlação entre os parâmetros avaliados pelo programa / Bipedal stance raises the center of mass, reduces the support area, and demands action of the postural control system, which maintains balance and orientation of body segments. Postural alterations may affect the control system, causing pain and motor dysfunctions. Postural assessment is fundamental for therapy recommendation, and some parameters related to the sagittal balance of the lumbar spine and pelvis, like the pelvic incidence angle (PI), have been studied in alterations of the spine. The goal of this study is to assess and look for correlations between postural measurements, with photographs marked in anatomical points, through the Postural Assessment Program (SAPO), and radiographic assessment of the spine to analyze the pelvic incidence angle (PI), using of the computer software Keops. Casuistry and methods: eighty-one healthy individuals of both sexes, aged between twenty and thirty-five were evaluated. Results: in the Keops assessment, 17.5 % of the sample had high pelvic incidence angles ( > 60o), 31.5 % had low pelvic incidence angles ( < 45o), and 51.2 % had medium pelvic incidence angles (between 46o and 59o). SAPO showed 12,5% of lordosis , 40% of retroversion and 47,5% normal curvature.In the right lateral view, the pelvic incidence angle had a moderate and positive correlation with the vertical alignment of the trunk and with the vertical alignment of the body and negative and moderate with the horizontal alignment of the pelvis. In the left lateral view the pelvic incidence angle had a weak and negative correlation with the horizontal alignment of the pelvis. There was no correlation between the parameters evaluated by the Keops program

Este estudo investigou como padrões de coordenação postural durante movimentos voluntários do corpo todo durante a postura ereta são afetados pelo envelhencimento usando o paradigma da relação entre velocidade e acurácia. Dez idosos e dez adultos jovens permaneceram em pé sobre uma plataforma de força e tiveram a posição instantânea do centro de pressão (CP) mostrada como feedback visual em um monitor a um metro a frente. Os participantes executaram movimentos contínuos rápidos e acurados na direção ântero-posterior com o corpo todo movendo a posição do CP entre alvos de diferentes larguras ou em diferentes freqüências de movimento, durante 45 s. Tempo de movimento (TM), deslocamento do CP, excursão dos ângulos articulares e atividade eletromiográfica (EMG) dos músculos do tornozelo, joelho e quadril foram analisados. Análises de componentes principais (PC) dos ângulos articulares foram também efetuadas. Flexibilidade da coordenação postural foi avaliada usando a abordagem da variedade não controlada (UCM) para testar as hipóteses de estabilização do tronco e do centro de massa (CM). Ambos grupos aumentaram o TM, atividade EMG e variáveis cinemáticas com um aumento na acurácia e freqüência. Sujeitos idosos aumentaram a amplitude dos ângulos articulares e EMG comparados aos adultos. Análise de PC mostrou alto acoplamento entre as articulações e a análise do UCM confirmou as hipóteses de estabilização do tronco e do CM. Os resultados indicam que padrões de coordenação postural são afetados pela acurácia dos movimentos do corpo todo e algumas dessas alterações estão relacionadas ao envelhecimento / This study examined how postural coodination patterns during voluntary whole-body movements in standing are affected by aging using the speed-accuracy trade-off paradigm. Ten elderly subjects and ten young adults stood on a force plate and had their center of pressure (COP) instantaneous position shown as visual feedback on a computer monitor one meter ahead. The participants performed continuous fast and accurate movements in the anterior-posterior direction with the whole body shifting their COP position; between targets with different widths or in different movement frequencies, during 45 s. Movement time (MT), COP displacement, joint angle excursion and eletromyographic (EMG) activity of ankle, knee and hip muscles were analyzed. Principal component (PC) analyses of the joint angles were also carried out. Flexibility of the postural coordination was evaluated using uncontrolled manifold (UCM) approach to test the trunk and the center of mass (COM) stabilization hypothesis. Both groups increased the MT, EMG activity and kinematic variables with an increase in the accuracy and frequency. Elderly subjects increased joint angles and EMG amplitude compared to adults. PC analysis showed a high coupling among the joints and the UCM analysis confirmed the trunk and the COM stabilization hypothesis. The results indicated that postural coordination patterns are affected by accuracy of whole-body movements and some changes are correlated with to aging

The somatosensory system has been implicated in the compensatory response of the nervous system to postural perturbations in humans and cats. The approach elicited - dubbed the Force Constraint Strategy - through a possible combined action of proprioceptive and cutaneous feedback, determines, and adjusts for, horizontal disturbances in various directions of a supporting surface. To understand the mechanisms underlying this strategy, we asked whether the response patterns of muscle proprioceptors correspond to those of electromyographic recordings (EMG) in the aforementioned Force Constraint experiments. The mechanical properties of the musculoskeletal system may also play a role in the restoration of stability. Thus, we also hypothesize that a proximal muscle would be relatively tightly tuned spatially whereas the distal muscle would exhibit a more diffuse spatial response distribution. To this end we selected the medial gastrocnemius (MG) and biceps femoris (BF) muscles to serve as our proximal and distal models respectively. Cats anesthetized using pentobarbital were set in a stereotaxic frame with the right leg positioned on a servo-controlled platform. The platform was shifted horizontally in 16 different directions according to a ramp-and-hold waveform. Intra-axonal recordings of activity from Ia afferents of BF and MG muscles were taken. Results indicate that the strategy makes use of information from the muscle proprioceptors. However, there is no differential response in tuning breadth with respect to muscle architecture. By characterizing the role of muscle proprioceptors in the mediation of corrective responses to perturbations of balance and stability, the results from this experiment can be used to verify biomechanical models, as well as further elucidate the underlying mechanisms of motor control.

ABSTRACT Postural deformities are a commonly encountered problem among children. Most of the aches and pains of adults are the result, not of injuries, but of the long-term effects of distortions in posture or alignment that have their origins in childhood or adolescence. Television, video entertainment, motorized transportation, fast food and lack of regular physical activity contribute to the poor physical condition of children. Childhood obesity has increased dramatically in the past decade. Countries in economic transition from underdeveloped to developed, such as South Africa, are particularly affected and have an increasing prevalence of obesity across all economic levels and age groups. In a developing country like South Africa, where overweight/obesity co-exists with undernutrition, there is an urgent need to prevent unhealthy trends in diet and physical activity. School screening is mandatory in schools in 26 states of the United States (US) for children between 10 and 16 years of age. Previous studies conducted in the US found that 160 out of 1000 people suffer from scoliosis (Boachie-Adjei & Lonner, 1996). This means that scoliosis is as prevalent as hypertension or diabetes mellitus. Identification of postural deformities at an early stage makes early treatment possible, which may, in future, prevent serious postural abnormalities. The aim of this review article is to define the concept of good posture, analyze normal postural development and postural deformities, and discuss some of the developmental factors affecting posture.

Developmental delays are known to exist in children with autism when compared to their typically developing peers. Foundations of these delays stem from the cognitive and motor performance realm, but information regarding specific characteristics, such as postural stability and sensory integration, are less defined. In this study, postural stability differences were investigated between children with autism and neurotypical children. Past research has shown the role of sensory integration during postural sway has been a strong indicator in showing developmental progress. Due to the focus of the protocol being on static balance, the Modified-Central Test of Sensory Interaction for Balance was used to measure postural stability. The age range for this study is set between 3 and 5 years of age and follows CTSIB protocol to assess 32 neurotypical developing children and compare their results to an archived data set containing CTSIB results from a sample of children with autism. Results from the study indicate that when the autism and neurotypical groups were compared, no significant main effect was found. Developmental differences were found across age groups in that 5 year olds displayed more stability than 4 year olds, but there was no difference between 3 and 4 year olds or 3 and 5 year olds. Further analyses of these developmental results indicated that children in the neurotypical group follow an expected developmental progression while children in the autism group display a divergence from this typical progression. Findings of this research add to the existing literature that children with autism display inconsistent developmental patterns which have a strong relationship with the delayed activity levels of these children. The knowledge and understanding of these delays will allow practitioners to implement specially designed programs to ensure that these children receive the activity that they need and deserve. / text

Rapid compensatory reach-to-grasp reactions are prevalent and functionally important responses to instability. The need to react very rapidly (to prevent falling) imposes temporal constraints on acquisition and processing of the visuospatial information (VSI) needed to guide the reaching movement. Previous results suggested that the CNS may deal with these constraints by using VSI stored in memory proactively, prior to perturbation-onset; however, the extent to which online visual control is necessary or sufficient to guide these reactions has not been established. Furthermore, the influence of memory-decay and concurrent cognitive-task on the performance of these reactions has not been examined. This Thesis employed a novel paradigm wherein the participant is stationary and a motor-driven handhold is positioned unpredictably in front of the participant for each trial. Reach-to-grasp reactions were evoked in healthy young and older adults by sudden unpredictable antero-posterior platform translation (barriers deterred stepping reactions). Liquid-crystal goggles were used to occlude vision either before (recall-delay time=0s/2s/5s/10s) or after perturbation-onset to force reliance on either stored- or online-VSI, respectively. Participants performed a spatial- or non-spatial-memory task during the delay-time in a subset of trials. When forced to rely on stored-VSI, all participants showed reduction in reach accuracy; however, a tendency to undershoot the handhold was exacerbated in the older adults. Forced-reliance on online-VSI led to similar delays in all participants; however, the older adults were more likely to reach with the “wrong” arm or raise both arms. Comparison with normal-VSI trials suggests that both sources of VSI are utilized when grasping the movable handhold for support, with stored-VSI predominating during initiation/transport and online-VSI contributing primarily to final target acquisition/prehension. In terms of recall-delay, both age groups showed comparable reduction in medio-lateral endpoint accuracy when delay-time was longest. Moreover, both cognitive tasks had similar (slowing) effects in both age-groups, suggesting these effects were related to generic attentional demands. However, the older-adults also showed a dual-task interference effect (poorer cognitive-task performance) that was specific to the spatial-memory-task. Further research is needed to establish whether interventions aimed to improve visual/cognitive processing speed, visuospatial memory, and/or attention capacity can reduce risk of falling among senior populations.