ABSTRACT
Abstract Introduction Moving the arm towards an object is a complex task. Movements of the arm joints must be well coordinated in order to obtain a smooth and accurate hand trajectory. Most studies regarding reaching movements address young subjects. Coordination differences in the neural mechanism underlying motor control throughout the life stages is yet unknown. The understanding of these changes can lead to a better comprehension of neuromotor pathologies and therefore to more suitable therapies. Methods Our purpose was to investigate interjoint coordination in three different aging groups (children, young, elderly). Kinematics and kinetics specific variables were analyzed focusing on defined parameters to get insight into arm coordination. Intersegmental dynamics was used to calculate shoulder and elbow torques assuming a 2-link segment model of the upper extremity (upper arm and forearm) with two friction-less joints (shoulder and elbow). A virtual reality environment was used to examine multidirectional planar reaching in three different directions (randomly presented). Results Seven measures were computed to investigate group interlimb differences: shoulder and elbow muscle torques (peak and impulse), work performed by shoulder and elbow joints, maximum velocity, movement distance, distance error at final position, movement duration and acceleration duration. Our data analysis showed differences between movement performances for all analyzed variables, at all ages. Conclusion We found that the intersegmental dynamics for the interlimb (left/right) comparisons were similar for the elderly and children groups as compared to the young. In addition, the coordination and control of motor tasks changes during life, becoming less effective in old age.
ABSTRACT
Introdução: Indivíduos após reconstrução do ligamento cruzado anterior mostram alterações cinéticas, cinemáticas e dos padrões energéticos durante a marcha. Estes pacientes expressam o desejo de recuperar rapidamente suas funções de marcha, incluindo caminhar em solo instável. Objetivo: Avaliar as mudanças em parâmetros cinemáticos da marcha de indivíduos após reconstrução do ligamento cruzado anterior (LCA) quando realizada em superfície estável e instável. Método: Seis indivíduos participaram do estudo: três pacientes com reconstrução do LCA e três indivíduos sadios pareados por idade e gênero. Participantes deambularam em velocidade confortável, enquanto filmados (câmeras de vídeo - 60Hz) no plano sagital. Resultados: Comparando os ângulos articulares nas duas condições: superfície estável e caminhando numa espuma (espessura: 5 cm, densidade: 33 kg/m3), observou-se que os pacientes foram mais lentos e tiveram menor amplitude de movimento em todas articulações em ambas condições. Conclusão: Pacientes apresentam marcha modificada, sendo que estas diferenças diminuíram gradualmente com o aumento do tempo de pós-operatório.
Subject(s)
Humans , Male , Female , Young Adult , Middle Aged , Biomechanical Phenomena , Anterior Cruciate Ligament , Gait , RehabilitationABSTRACT
INTRODUCTION: The purpose of the current study was to examine whether age-related differences are exhibited in the relative contributions of vision and proprioception with initial hand position to the control of movement distance of single-joint reaching movements. METHODS: We use a virtual reality display to systematically change the relationship between the actual hand position and the displayed hand position (virtual position) as subjects' positioned a cursor within a start circle. Visual feedback of the reaching hand was only available before movement onset. Two groups of subjects (older and young) reached to two different visual targets (115º and 125º elbow angle) from four possible starting locations (90º, 95º, 100º, 105º elbow angle) under four virtual/actual dissociation conditions (0º, 5º, 10º, 15º). RESULTS: For the mismatched conditions movement distance was generally longer for the older adults as compared to the younger. Also, the younger group better scaled their movement extent with cursor initial location, whereas, the older group showed scaling with hand location. Our results indicate age-related differences in the effects of initial position information when vision and proprioception initial information were dissociated. CONCLUSION: The young were able to completely rely on visual information through feedforward mechanism applying acceleration amplitude manipulation for controlling movement distance. In contrast, older subjects relied on proprioceptive information for the scaling of peak velocity with movement distance, suggesting more reliance on feedback-mediated error-correction mechanisms during the course of movement.
ABSTRACT
Previous studies of gait analysis in patients following reconstructive anterior cruciate ligament (ACL) surgery have shown changes in kinematics, kinetics and energy patterns in the lower limb. Usually these patients perform complaint surface training during clinical treatment. The purpose of this study was to evaluate the changes in selected gait kinematic parameters following ACL reconstruction while walking on an unstable surface. We tested 16 subjects: eight patients who underwent ACL reconstruction, at four weeks after the surgical intervention; and eight healthy subjects (control group) matched by age and gender. Participants walked at a self-selected comfortable speed on an 8 m-walkway while sagittal plane kinematic data of the principal lower limb joints (hip, knee and ankle) were collected using 60-Hz cameras. We compared the joint angles under three conditions: (A) walking on stable ground, (B) walking on a foam mat (5 cm thick; 33 kg m-3 density) and (C) back at the normal ground. Results showed that ACL patients were slower and had smaller range of motion at all joints as compared to the control group under all conditions; however the repeated exposure to unstable surface may help changes in such patients. Further investigation is necessary to expand our understanding and may improve the development of more effective rehabilitation treatments.
Estudos avaliando a marcha em pacientes com reconstrução do ligamento cruzado anterior (LCA) mostram diferenças em parâmetros cinemáticos, cinéticos e energéticos. É comum para estes pacientes realizar treinamento de marcha em superfícies instáveis durante o tratamento clinico. O objetivo deste estudo foi avaliar as mudanças em parâmetros cinemáticos específicos da marcha após a cirurgia de reconstrução do LCA quando caminhando em superfície instável. Foram testados 16 indivíduos: oito pacientes que realizaram a cirurgia de reconstrução do LCA com quatro semanas após a cirurgia; e oito indivíduos saudáveis (grupo controle) pareados por idade e gênero. Os participantes caminharam em velocidade confortável numa plataforma de 8 m enquanto os dados cinemáticos do plano sagital das articulações do membro inferior (quadril, joelho e tornozelo) eram obtidos com câmeras de 60 Hz. Foram comparados os ângulos articulares em três diferentes condições: (A) caminhando na superfície estável, (B) caminhando num colchão (5 cm de espessura e densidade de 33 kg m-3), e (C) de volta na superfície estável. Os resultados mostraram que os pacientes andaram mais devagar e apresentaram maior amplitude de movimento quando comparados ao grupo controle em todas as condições testadas, entretanto a exposição repetida a instabilidade pode auxiliar na promoção de mudanças neste tipo de paciente. Novos estudos são necessários para expandir nosso entendimento e talvez melhore o desenvolvimento de técnicas de reabilitação mais efetivas.