Intraindividual Variability of Neuromotor Function Predicts Falls Risk in Older Adults and those with Type 2 Diabetes

The current study was designed to examine the effect of increasing age and type 2 diabetes on the average responses and inter- and intra-individual variability of falls risk, reaction time, strength, and walking speed for healthy older adults and older persons with type 2 diabetes (T2DM). Seventy-five older individuals (controls) and 75 persons with T2DM aged between 50-79 years participated in the study. Assessments of falls risk, reaction time (RT), knee extension strength and walking speed were conducted. The results revealed that advancing age for both control and T2DM groups was reflected by a progressive increase in falls risk, decreased leg strength and a decline (i.e. slowing) of reactions and gait speed. Conversely, the level of intra-individual variability for the RT, strength and gait measures increased with increasing age for both groups, with T2DM persons tending to be more variable compared to the healthy controls of similar age. In contrast to the intra-individual changes, measures of inter-individual variability revealed few differences between the healthy elderly and T2DM individuals. Taken together, the findings support the proposition that intra-variability of neuromotor measures may be useful as a biomarker for the early detection of decline in physiological function due to age or disease

HANDSTAND BALANCE MOTOR CONTROL MECHANISMS

The goal of a handstand, a fundamental skill in gymnastics, is to maintain a balanced stance by controlling center of mass (COM) position. Successful handstands predominantly use wrist torque to control the COM in the anterior-posterior (AP) plane. The aim of this study was to determine the underlying motor control mechanisms necessary to maintain a strong handstand stance through analysis of joint angle and COM position variability. Full body 3D kinematic data were collected on three competitive level gymnasts during 30 s floor handstands. Variability of joint angles were consistently higher than the center of mass, demonstrating that joints self-organize in a motor control strategy to produce torques in order to control the COM. Using multiple linear regression analysis, it was found that shoulder flexion/extension variability was the largest contributor to controlling the COM in both the medio-lateral (ML) and AP planes

Cross-Limb Dynamics of Postural Tremor Due to Limb Loading to Fatigue: Neural Overflow but not Coupling

Many experiments have shown independence of the index finger dynamics under bilateral postural tremor protocols. Here we investigated in young adults the dynamics of bilateral multidirectional postural tremor and forearm muscle activity under the progressively fatiguing conditions supporting an external weight to the point of induced postural failure. When no loads were applied, tremor in the vertical (VT) and mediolateral (ML) directions was similar with prominent peaks within 2- to 4-Hz and 8- to 12-Hz bandwidths. Contrastingly tremor in the anterior-posterior (AP) direction was characterized by a single peak between 0 and 2 Hz. Although no tremor coupling occurred cross limbs, strong within-limb coupling was found between ML and VT directions when no loads were applied (coherence range: 0.77-0.85), implying that these oscillations are related and likely derived from mechanical sources. Applying an external load to the index finger(s) led to significant increases in the amplitude of VT tremor and EMG activity within that limb but also caused increases in tremor directions not aligned with the gravitational vector (AP and ML). Significant increases in VT and ML tremor and EMG activity in the contralateral (unloaded) limb were also found when a single index finger was loaded; however, this bilateral increase did not align with increases in interlimb coupling (coherenc

Gamma Group-The Pale Horse: A proposal in response to a commercial air transportation study ort study

A conventional remotely piloted vehicle (RPV) was designed to operate in a fictional 'Aeroworld' as a 30 passenger aircraft. The topics addressed include: economic/cost analysis, aerodynamics, weight and structures, propulsion, stability and control, and performance

Coordination changes in the early stages of learning to cascade juggle

The experiment was setup to examine the coordination changes in assembling the movement form of 3-ball cascade juggling. Eight adult participants learned to juggle over 4 weeks of practice. Juggling scores were recorded at each session and performance was videotaped at eight selected sessions for purposes of movement analysis. Once the basic spatial and temporal constraints on cascade juggling were satisfied, and the figure-8 juggling mode was established, temporal modulations of the relative motions of the hands were emphasized. All participants learned to juggle and the increase over practice in the number of consecutive balls caught was best fit with a power law. The non-proportional rate of performance increment was consistent with the qualitative changes in the form of the hand and ball movement kinematics that occurred over practice

Mudança em aprendizagem motora: Uma perspectiva de Coordenação e Controle

This paper examines the issue of change in motor learning from a dynamical systems framework. There is qualitative and quantitative change to performance over time that is driven by an embedded set of evolving dynamical systems each with its own time scale of change. Learning arises through searching and the evolution and dissolution of the stable dynamical regions of coordination modes for a given task. Learning then is discovering (searching for) the dynamic laws. The nature of the relevant of information that facilitates the search and the transitions of the stable modes of performance is the key to the efficacy of learning strategies.Este trabalho examina a questão relativa a mudanças em aprendizagem motora a partir do esquema de referência dos sistemas dinâmicos. Existe mudança qualitativa e quantitativa no desempenho ao longo do tempo que é resultado de um conjunto intrincado de sistemas dinâmicos em evolução, cada um em sua própria escala de tempo de mudança. A aprendizagem ocorre através da busca e da evolução e dissolução de regiões dinâmicas estáveis dos modos de coordenação para uma dada tarefa motora. Assim, o aprendizado é a descoberta (busca) de leis dinâmicas. A natureza das informações relevantes que facilitam a busca e as transições de modos estáveis de performance é a chave para a eficácia de estratégias de aprendizagem

ACCURACY OF BODY MASS PREDICTION USING SEGMENTAL INERTIA PARAMETERS MODELLED FROM PHOTOGRAPHIC IMAGES

The aim of this study was to evaluate the accuracy between the measured and predicted body mass, using the methods of Gittoes et al. (2009), and investigate the relationship between mass and stature and this accuracy. Fifteen male, recreational athletes from a university’s sporting population took part in the study. Measured whole-body masses were compared with predicted whole-body masses calculated using photographic dimensional data and an inertia model. Mean absolute error between measured and predicted whole-body mass was 5.42 ± 2.92 %. A strong, negative correlation between measured whole-body mass and relative % error (r = -0.80) and a normalising value and relative % error was found. It is suggested that for similar participants errors could be up to ± 10% for participants with body masses much greater or less than 71 kg or normalising values equating to 1230 Nm

DYNAMICS OF HANDSTAND BALANCE

The purpose of this study was to identify parameters that are associated with more successful motor control during handstand performance. For two groups of gymnasts, ‘less skilled’, who were able to hold handstands for 4 to 6s, and ‘more skilled’, who held handstands in excess of 10s, centre of mass (CoM) and centre of pressure (CoP) motion during the initial 3s of the handstand stability phase were analysed, as well as the 6 to 9s stabilised period for the more skilled gymnasts (balance phase). Time-space, time-frequency, CoM-CoP coherence, Hurst Exponent and CoM-CoP causality were investigated in anterior-posterior (AP) and medio-lateral (ML) directions. Characteristics of CoM and CoP for more and less skilled gymnasts were found to be directionally dependent (AP and ML). Nonlinear and frequency domain measures distinguished skill levels to a greater extent than time-space domain measures. The study findings shed light on the subtleties and complexities of the mechanics and dynamics that define CoM and CoP relations with increased skill level, that add to both basic and applied understanding

LIMIT CYCLE REPRESENTATION OF THE GYMNASTICS LONGSWING

Human movement science is searching for ways to capture global dynamics of our complex multi-segment system. The aim of this study was to explore differences in a limit cycle representation of longswings on high bar as a function of skill level. One elite international, one collegiate, and one novice gymnast performed four consecutive longswings on high bar. Through the novel representation of the longswing as a limit cycle, and exploration of the limit cycle characteristics, it is shown that higher frequency, more phase coherent oscillations, and lower limit cycle variability occurs as a function of skill level. It is suggested that this candidate collective variable be explored as a global indicator of skill level and learning that can provide insight into the efficiency of the mechanical system

THE INFLUENCE OF EXPERIENCE ON KINETIC CHARACTERISTICS OF THE LOOPED LONGSWING

The aim of this study was to increase understanding of the strategies performers use to complete the looped longswing (LLS) in order to provide useful information for the development of this skill. For an elite gymnast and two novice performers, kinematic and kinetic data were collected during 5 series of three LLS (CODA motion analysis system, 200 Hz; instrumented high bar, 1 kHz). Inverse dynamics were employed to determine joint kinetics during the second LLS in each trial for each performer. The elite gymnast performed positive work at the hips during the ownswing resulting in hip flexion, which facilitated the control of proceeding functional phase actions. Peak shoulder power values were highest for the elite gymnast and lowest for the least experienced novice participant