The hand trajectory of motion during the performance of one-dimensional point-to-point movements has been shown to be marked by motor primitives with a bell-shaped velocity profile. Researchers have investigated if motor primitives with the same shape mark also complex upper-limb movements. They have done so by analyzing the magnitude of the hand trajectory velocity vector. This approach has failed to identify motor primitives with a bell-shaped velocity profile as the basic elements underlying the generation of complex upper-limb movements. In this study, we examined upper-limb movements by analyzing instead the movement components defined according to a Cartesian coordinate system with axes oriented in the medio-lateral, antero-posterior, and vertical directions. To our surprise, we found out that a broad set of complex upper-limb movements can be modeled as a combination of motor primitives with a bell-shaped velocity profile defined according to the axes of the above-defined coordinate system. Most notably, we discovered that these motor primitives scale with the size of movement according to a power law. These results provide a novel key to the interpretation of brain and muscle synergy studies suggesting that human subjects use a scale-invariant encoding of movement patterns when performing upper-limb movements.

It has been argued that the central nervous system relies on combining simple movement elements (i.e. motor primitives) to generate complex motor outputs. However, how movement elements are generated and combined during the acquisition of new motor skills is still a source of debate. Herein, we present results providing new insights into the role of movement elements in the acquisition of motor skills that we obtained by analysing kinematic data collected while healthy subjects learned a new motor task. The task consisted of playing an interactive game using a platform with embedded sensors whose aggregate output was used to control a virtual object in the game. Subjects learned the task over multiple blocks. The analysis of the kinematic data was carried out using a recently developed technique referred to as “movement element decomposition.” The technique entails the decomposition of complex multi‐dimensional movements in one‐dimensional elements marked by a bell‐shaped velocity profile. We computed the number of movement elements during each block and measured how closely they matched a theoretical velocity profile derived by minimizing a cost function accounting for the smoothness of movement and the cost of time. The results showed that, in the early stage of motor skill acquisition, two mechanisms underlie the improvement in motor performance: 1) a decrease in the number of movement elements composing the motor output and 2) a gradual change in the movement elements that resulted in a shape matching the velocity profile derived by using the above‐mentioned theoretical model.

Introdução: Estudos apontam uma alta prevalência de alterações posturais da coluna entre crianças e adolescentes devido o uso de mochilas. Há discussão sobre qual o peso ideal que deve ter a mochila, sendo que as opiniões variam de 10 a 15% do peso corporal. É importante a identificação das posturas inadequadas em crianças e adolescentes a fim de prevenir possíveis alterações que geram distúrbios musculoesqueléticos. Objetivo: Verificar alterações posturais provenientes do uso de mochilas em escolares. Métodos: Estudo transversal com 78 indivíduos com idade entre 7 e 14 anos. Foram tiradas fotografias com e sem mochila, as quais posteriormente foram avaliadas pelo Software de avaliação postural (SAPO). As variáveis numéricas foram analisadas pelo teste t de student pareado e as variáveis qualitativas pelo Qui-quadrado. Resultados: O tipo mais freqüente de mochila foi o de rodinhas, a média do peso da mochila foi de 11% da média do peso corporal das crianças e 60,3% destas carregam um ou dois livros. As alterações significativas foram: ângulo frontal do membro inferior direito, translação anterior da cabeça, posteriorização da cabeça, extensão de tronco, inclinação posterior do corpo e anteversão da pelve. Conclusão: O peso da mochila altera a postura da criança a partir de 11% da massa corporal, indicando que o menor peso possível deve ser usado nesta fase do desenvolvimento corporal.

| Introduction:Despite the evaluation of technology in human movement evaluation, the high cost and specific training of these kind of technology are not feasible for clinical practice. An ideal videogrammetry system should be easy to use, low cost, with minimal equipment, and fast realization. Objective: This paper aims to determine if CvMob is a reliable tool for the evaluation of bidimensional human gait. Methods and materials: The sample was composed of 56 healthy individuals who were simultaneously filmed by CvMob and Vicon system cameras. Linear trajectories and angular measurements were compared to validate the CvMob system, and inter and intrarater findings of the same measurements were used to determine reliability. Results: A strong correlation (r s mean = 0.988) of the linear trajectories between systems and inter and intrarater analysis were found. According to the Bland-Altman method, the angles that had good agreement between systems were maximum flexion and extension of the knee and dorsiflexion range of motion and stride length. Conclusion: The CvMob is a reliable tool for analysis of linear motion and lengths in bidimensional evaluations of human gait. The angular measurements demonstrate high agreement for the knee joint; however, the hip and ankle measurements were limited by differences between systems.

Theories of embodied cognition hypothesize interdependencies between psychological well-being and physical posture. The purpose of this study was to assess the feasibility of objectively measuring posture, and to explore the relationship between posture and affect and other patient centered outcomes in breast cancer survivors (BCS) with persistent postsurgical pain (PPSP) over a 12-week course of therapeutic Qigong mind-body training. Twenty-one BCS with PPSP attended group Qigong training. Clinical outcomes were pain, fatigue, self-esteem, anxiety, depression, stress and exercise self-efficacy. Posture outcomes were vertical spine and vertical head angles in the sagittal plane, measured with a 3D motion capture system in three conditions: eyes open (EO), eyes open relaxed (EOR) and eyes closed (EC). Assessments were made before and after the Qigong training. The association between categorical variables (angle and mood) was measured by Cramer’s V. In the EO condition, most participants who improved in fatigue and anxiety scales also had better vertical head values. For the EOR condition, a moderate correlation was observed between changes in vertical head angle and changes in fatigue scale. In the EC condition, most of the participants who improved in measures of fatigue also improved vertical head angle. Additionally, pain severity decreased while vertical spine angle improved. These preliminary findings support that emotion and other patient centered outcomes should be considered within an embodied framework, and that Qigong may be a promising intervention for addressing biopsychosocially complex interventions such as PPSP in BCSs.