Relationships between coordination,active drag and propelling efficiency in crawl

This study examines the relationships between the index of coordination (IdC) and active drag (D) assuming that at constant average speed, average drag equals average propulsion. The relationship between IdC and propulsive efficiency (e_p) was also investigated at maximal speed. Twenty national swimmers completed two incremental speed tests swimming front crawl with arms only in free condition and using a measurement of active drag system. Each test was composed of eight 25-m bouts from 60% to 100% of maximal intensity whereby each lap was swum at constant speed. Different regression models were tested to analyse IdC–D relationship. Correlation between IdC and e_p was calculated. IdC was linked to D by linear regression (IdC = 0.246 · D − 27.06; R² = 0.88, P < .05); swimmers switched from catch-up to superposition coordination mode at a speed of ∼1.55 m s⁻¹ where average D is ∼110 N. No correlation between IdC and e_p at maximal speed was found. The intra-individual analysis revealed that coordination plays an important role in scaling propulsive forces with higher speed levels such that these are adapted to aquatic resistance. Inter-individual analysis showed that high IdC did not relate to a high e_p suggesting an individual optimization of force and power generation is at play to reach high speeds.     

Exercise can improve physical self perceptions in adolescents with low motor competence

Adolescents with low motor competence have diminished perceptions of their physical self and tend to avoid physical activities. This study examined the outcomes of an exercise intervention that focused on improving aerobic fitness, strength, and self-perceptions in the physical domain in adolescents with poor motor coordination. The sample included 35 adolescents with low motor competence, comprising boys (n = 25) and girls (n = 10) ranging in age from 13 to 17 years, who attended two sessions per week in the 13 week exercise intervention study (AMP it up). Physical self-perceptions were measured before and after the intervention using the Physical Self Perception Profile and Perceived Importance Profile. Significant improvements in perceived Physical Condition, Attractive Body and Physical Strength sub domain scores were identified between pre and post-test. Adjusting for age, gender, BMI and attendance, regression analyses revealed that Attractive Body was the strongest predictor of Physical Self Worth at pre-test, joined by Physical Condition at post-test. This exercise intervention had a positive impact on adolescent physical self-perceptions, in particular males, with improvements in those sub domains specifically related to the exercise program. Changes in specific aspects of Physical Self Worth can be facilitated by exercise interventions, after a relatively short period of time, in adolescents with poor motor coordination.     

A crossover randomised and controlled trial of the impact of active video games on motor coordination and perceptions of physical ability in children at risk of Developmental Coordination Disorder

BackgroundImpaired motor development can significantly affect a child’s life and may result in an increased risk of a range of physical and psychological disorders. Active video game (AVG) interventions have been demonstrated to enhance motor skills in children with Developmental Coordination Disorder (DCD); however a home-based intervention has not been assessed.ObjectivesThe primary aim of this study was to compare the changes in motor coordination between a 16 week period of AVG use, with 16 weeks of normal activities (NAG). The secondary aim was to compare the child and parent perceptions of their physical performance between the AVG and NAG conditions.MethodsTwenty-one 9–12 year olds (10 males) were confirmed to be at risk of DCD (⩽16th percentile Movement Assessment Battery for Children-2nd edition (MABC-2) and ⩽15th percentile Developmental Coordination Disorder Questionnaire (DCDQ)) and participated in this crossover randomised and controlled trial. Data was collected at study entry, after the first 16 week condition and following the final 16 week condition, including; (1) the MABC-2, (2) three-dimensional motion analysis of single leg balance and finger–nose tasks, and (3) parent perception of physical skills. Participant perception of physical skills was collected only after the first and second conditions.ResultsThere was no significant difference between AVG and NAG for any of the primary variables including the MABC-2, balance centre-of-mass path distance and finger–nose path distance. There was no significant intervention effect for secondary measures of motor coordination; however the children perceived their motor skills to be significantly enhanced as a result of the AVG intervention in comparison to the period of no intervention.ConclusionA 16 week home based AVG intervention did not enhance motor skills in children with DCD, although they perceived their physical skills to be significantly improved.Trial Registration: Australia and New Zealand Clinical trials Registry (ACTRN 12611000400965).     

The role of eye movements in motor sequence learning

An experiment that utilized a 16-element movement sequence was designed to determine the impact of eye movements on sequence learning. The participants were randomly assigned to two experimental groups: a group that was permitted to use eye movements (FREE) and a second group (FIX) that was instructed to fixate on a marker during acquisition (ACQ). A retention test (RET) was designed to provide a measure of learning, and two transfer tests were designed to determine the extent to which eye movements influenced sequence learning. The results demonstrated that both groups decreased the response time to produce the sequence, but the participants in the FREE group performed the sequence more quickly than participants of the FIX group during the ACQ, RET and the two transfer tests. Furthermore, continuous visual control of response execution was reduced over the course of learning. The results of the transfer tests indicated that oculomotor information regarding the sequence can be stored in memory and enhances response production.     

Sleep deprivation impairs object recognition in mice

Many studies in animals and humans suggest that sleep facilitates learning, memory consolidation, and retrieval. Moreover, sleep deprivation (SD) incurred after learning, impaired memory in humans, mice, rats, and hamsters. We investigated the importance of sleep and its timing in an object recognition task in OF1 mice subjected to 6h SD either immediately after the acquisition phase (0-6 SD) or 6h later (7-12 SD), and in corresponding undisturbed controls. Motor activity was continuously recorded with infrared sensors. All groups explored two familiar, previously encountered objects to a similar extent, both at the end of the acquisition phase and 24h later during the test phase, indicating intact familiarity detection. During the test phase 0-6 SD mice failed to discriminate between the single novel and the two familiar objects. In contrast, the 7-12 SD group and the two control groups explored the novel object significantly longer than the two familiar objects. Plasma corticosterone levels determined after SD did not differ from time-matched undisturbed controls, but were significantly below the level measured after learning alone. ACTH did not differ between the groups. Therefore, it is unlikely that stress contributed to the memory impairment. We conclude that the loss of sleep and the activities the mice engaged in during the SD, impaired recognition memory retrieval, when they occurred immediately after acquisition. The delayed SD enabled memory consolidation during the 6h when the mice were allowed to sleep, and had no detrimental effect on memory. Neither SD schedule impaired object familiarity processing, suggesting that only specific cognitive abilities were sensitive to the intervention. Sleep may either actively promote memory formation, or alternatively, sleep may provide optimal conditions of non-interference for consolidation.     

Event-related fMRI of category learning: differences in classification and feedback networks

Eighteen healthy young adults underwent event-related (ER) functional magnetic resonance imaging (fMRI) of the brain while performing a visual category learning task. The specific category learning task required subjects to extract the rules that guide classification of quasi-random patterns of dots into categories. Following each classification choice, visual feedback was presented. The average hemodynamic response was calculated across the eighteen subjects to identify the separate networks associated with both classification and feedback. Random-effects analyses identified the different networks implicated during the classification and feedback phases of each trial. The regions included prefrontal cortex, frontal eye fields, supplementary motor and eye fields, thalamus, caudate, superior and inferior parietal lobules, and areas within visual cortex. The differences between classification and feedback were identified as (i) overall higher volumes and signal intensities during classification as compared to feedback, (ii) involvement of the thalamus and superior parietal regions during the classification phase of each trial, and (iii) differential involvement of the caudate head during feedback. The effects of learning were then evaluated for both classification and feedback. Early in learning, subjects showed increased activation in the hippocampal regions during classification and activation in the heads of the caudate nuclei during the corresponding feedback phases. The findings suggest that early stages of prototype-distortion learning are characterized by networks previously associated with strategies of explicit memory and hypothesis testing. However as learning progresses the networks change. This finding suggests that the cognitive strategies also change during prototype-distortion learning.     

General self-concept and life satisfaction for boys with differing levels of physical coordination: the role of goal orientations and leisure participation

Participation in leisure-time activities, self-concept perceptions and individual dispositional goal orientations were examined as mediators of relationships between physical coordination and self-evaluations of life satisfaction and general self-concept for 173 boys aged 10-13 years. Participants completed seven-day activity diaries and 12-month retrospective recall questionnaires recording participation in leisure-time activities. Self-report measures of self-concept, global life satisfaction and dispositional goal orientations were also completed. Results showed that boys with moderate to severe physical coordination difficulties had significantly lower self-concept perceptions of physical ability and appearance, peer and parent relations and general self-concept, as well as lower life satisfaction than boys with medium to high levels of physical coordination. The relationships between boys' physical coordination and their self-perceptions of life satisfaction and general self-concept were significantly influenced by individual self-concept appraisals of physical ability and appearance, peer and parent relations. Adopting task-oriented goals was found to positively change the relationship between physical coordination and both general self-concept and life satisfaction. Team sport participation positively mediated the relationship between physical coordination and life satisfaction. The potential for team sport participation and adoption of task-oriented goals to influence life satisfaction for boys with differing levels of physical coordination was discussed.     

Neural modeling and imaging of the cortical interactions underlying syllable production

This paper describes a neural model of speech acquisition and production that accounts for a wide range of acoustic, kinematic, and neuroimaging data concerning the control of speech movements. The model is a neural network whose components correspond to regions of the cerebral cortex and cerebellum, including premotor, motor, auditory, and somatosensory cortical areas. Computer simulations of the model verify its ability to account for compensation to lip and jaw perturbations during speech. Specific anatomical locations of the model's components are estimated, and these estimates are used to simulate fMRI experiments of simple syllable production.     

An especial skill: Support for a learned parameters hypothesis

We tested the ‘learned parameters’ hypothesis as an explanation of the ‘especial skill effect’. Outcome attainment and movement kinematics were recorded for 10 expert and 10 novice players performing basketball free-throw shots at five distances (11-19 ft) with a regular and heavy weight basketball. As predicted, experts performed better than expected relative to the regression equation at the 15 ft, free-throw line with the regular basketball, supporting the ‘especial skill effect’. This effect was not present for the experts when shooting with the heavy ball. Novices did not show an advantage at the free-throw line when performing with either ball. Although the outcome attainment scores support the ‘learned parameters’ hypotheses, kinematic analysis failed to identify differences in the movement pattern for the especial skill, suggesting that these skills (i.e., shooting at different distances) are not governed by separate motor programs.     

Sit-to-stand movement in children: A longitudinal study based on kinematics data

Although the ability to stand from a seated posture is relevant for clinical practice, there are few studies investigating the process of acquisition and refinement of the motor components involved in sit-to-stand movement (STS) in children. Therefore, this longitudinal study aims to describe kinematic characteristics of the STS movement in children from 12 to 18 months, and also to investigate the relationship between changes in STS movement and childrens’ daily-life mobility. Ten healthy children were evaluated at 12,13,14,15 and 18 months of age. A motion analysis system was used to measure total duration of STS movement and angular movements of each joint, and frequencies of successful and unsupported STS were obtained. The Pediatric Evaluation of Disability Inventory was used to assess childrens’ daily-life mobility. Results showed that children tend to increase the frequency of successful trials over the months by reducing the total duration and decreasing peak ankle dorsiflexion and trunk flexion during STS. Children also started to stand up from chair with decreased trunk flexion angle among ages. At the end of the STS, we observed decreases in trunk flexion and knee flexion over age. Furthermore, kinematic characteristics that reflect improvements in STS movement are related to better performance of functional skills and decreased level of assistance provided by the caregiver in daily-life mobility of younger children. However, the strength of these associations decreases from 14 months of age onwards.