The Associations of Objectively Measured Physical Activity, Fundamental Motor Skills and Time in Sedentary Behavior in Children: A Cross-Sectional Study

Reduced levels of children’s physical activity (PA) and fundamental motor skills (FMS) along with increased sedentary behaviors have been observed in recent years. Yet, associations between these variables are not yet well established. This study aimed to observe the associations between FMS, PA and sedentary time in elementary school children. We evaluated 148 children (70 boys; Mage = 8.7, SD = 1.4 years old) from a private school using the Test of Gross Motor Development – Second Edition (TGMD-2) to measure FMS and examine locomotor, object control, and gross motor skills. We used accelerometry to measure PA performed on weekdays, weekends and total PA. We used descriptive statistics, partial correlations controlling for sex and age, and linear regression adjusted for sex and equivalent motor age to explain the relationships. Total moderate to vigorous PA (MVPA) (β: 0.153; p = .009) and weekend MVPA (β: 0.171; p = .003) were significantly associated with FMS, regardless of gender and equivalent motor age. Sedentary time was not significantly associated with FMS ( p = .065). Girls and boys who met PA recommendations (≥60 minutes/day of moderate to vigorous PA) had higher frequencies of high ratings on the TGMD-2 ( p < .001 e p = .001, respectively). MVPA was associated with children’s FMS development, possibly affecting the quality of movement performed in children's daily lives.

Neural Kinesthetic Contribution to Motor Imagery of Body Parts: Tongue, Hands, and Feet

Motor imagery (MI) is assimilated to a perception-action process, which is mentally represented. Although several models suggest that MI, and its equivalent motor execution, engage very similar brain areas, the mechanisms underlying MI and their associated components are still under investigation today. Using 22 Ag/AgCl EEG electrodes, 19 healthy participants (nine males and 10 females) with an average age of 25.8 years old (sd = 3.5 years) were required to imagine moving several parts of their body (i.e., first-person perspective) one by one: left and right hand, tongue, and feet. Network connectivity analysis based on graph theory, together with a correlational analysis, were performed on the data. The findings suggest evidence for motor and somesthetic neural synchronization and underline the role of the parietofrontal network for the tongue imagery task only. At both unilateral and bilateral cortical levels, only the tongue imagery task appears to be associated with motor and somatosensory representations, that is, kinesthetic representations, which might contribute to verbal actions. As such, the present findings suggest the idea that imagined tongue movements, involving segmentary kinesthetic actions, could be the prerequisite of language.

Motor Dyscoordination and Alteration of Functional Correlation Between DGKγ and PKCγ in Senescence-Accelerated Mouse Prone 8 (SAMP8)

Senescence-accelerated mouse prone 8 (SAMP8) is an animal model of age-related central nervous system (CNS) disorders. Although SAMP8 shows deficits in learning, memory, and emotion, its motor coordination has not been clarified. We have recently reported that DGKγ-regulated PKCγ activity is important for cerebellar motor coordination. However, involvement of the functional correlation between the kinases in age-related motor dyscoordination still remains unknown. Therefore, we have investigated the motor coordination in SAMP8 and involvement of the functional correlation between DGKγ and PKCγ in the age-related motor dyscoordination. Although 6 weeks old SAMP8 showed equivalent motor coordination with control mice (SAMR1) in the rotarod test, 24 weeks old SAMP8 exhibited significantly less latency in the rotarod test and more frequent slips in the beam test compared to the age-matched SAMR1. Furthermore, 24 weeks old SAMP8 showed the higher locomotor activity in open field test and Y-maze test. Western blotting revealed that DGKγ expression decreased in the cerebellum of 24 weeks old SAMP8, while PKCγ was upregulated. These results suggest that SAMP8 is a useful model of age-related motor dysfunction and that the DGKγ-regulated PKCγ activity is involved in the age-related motor dyscoordination.

Análisis comparativo de un programa educación física en niños con discapacidad auditiva sobre la edad motora equivalente (Comparative analysis of the effect of physical education program of motor age equivalent in children with hearing disability)

Objetivo: Analizar de manera comparativa un programa educación física en niños con discapacidad auditiva sobre la edad motora equivalente. Método: El diseño de la investigación fue de corte cuasi-experimental, con muestreo por conveniencia, participaron 38 niños diagnosticados discapacidad auditiva de una edad promedio de 7.4±0.9 años, matriculados en dos escuelas de la ciudad de Mexicali, Baja California. México. Los participantes se dividieron aleatoriamente en un grupo control (n=15) y un grupo experimental (n=23), determinado la edad motora equivalente mediante el inventario de desarrollo Battelle, mediante pruebas de control muscular, coordinación corporal, locomoción, motricidad fina, motricidad perceptiva. El programa de educación física tuvo una duración de 4 meses, con sesiones 5 veces a la semana, cada sesión duro 50 minutos, realizando una serie de tareas que enfatizaran las coordinación motora y comunicándose con los alumnos mediante la lengua de señas mexicana. Resultados: El análisis de varianza (ANOVA) mixtas 2 x 2 reporto una interacción doblemente significativa entre los grupos y las mediciones de la variable edad motora equivalente (p=0.05), los porcentajes de cambio resultaron 12.9Δ% del grupo experimental y 4.9Δ% del grupo control. Conclusión: La aplicación de un programa de educación física durante cuatro meses influencia de manera positiva mejora la edad motora equivalente en escolares con discapacidad auditiva.Abstract. Objective: To analyze in a comparative way the effect of a physical education program on the equivalent motor age in children with hearing disability. Method: The research design was quasi-experimental, with convenience sampling; involving 38 children with diagnosed hearing disability with an average age of 7.4 ± 0.9 years, enrolled in two schools in the city of Mexicali, Baja California, Mexico. The participants were randomly divided into a control group (n=15) and an experimental group (n=23). The motor age equivalent was determined using the education Battelle developmental inventory, through tests of muscle control, body coordination, locomotion, fine motor skills, and perceptive motricity. The physical education program was performed during 4 months, with five 50-minute sessions per week, focusing on tasks that emphasized motor coordination and communicating with students through the Mexican sign language. Results: The mixed analysis of variance (ANOVA) 2 x 2 reported a doubly significant interaction between the groups and the measurements of the motor equivalent age variable (p=0.05). The percentages of change were 12.9Δ% for the experimental group, and 4.9Δ % for the control group. Conclusion: The application of a physical education program during four months improves the equivalent motor age in school children with hearing disability.

Charabancs and Social Class in 1930s Britain

The renowned writer J. B. Priestley suggested in 1934 that the motor-coach had annihilated the old distinction between rich and poor passengers in Britain. This article considers how true this was by examining the relationship between charabancs, motor coaches and class. It shows that this important vehicle of inter-war working class mobility had a complicated relationship with class, identifying three distinct forms of this method of travel. It positions the charabanc alongside historical responses to unwelcome steamer and railway day-trippers, and examines how resorts provided separate class-based entertainment for these holidaymakers. Using the case study of a new charabanc-welcoming pub, the Prospect Inn, it proposes that, in the late 1930s, some pubs were beginning to offer charabanc customers facilities that were almost the match of their middle class equivalent. Motor coaches and charabancs contributed to the process of social convergence in inter-war Britain.

Dynamic Aggregation Method of Induction Motors Based on Coherent Characteristics

Parameters of induction motors have crucial effects on power system simulation. This paper proposes a dynamic aggregation method of induction motors. In this method, firstly, starting off the electromechanical models of induction motors, taking the coefficients of the electromechanical equations and steady state slips of motors as the characteristic vectors, motors are grouped with fuzzy C-means clustering method. Then, electromechanical equations of the equivalent motor are obtained by averaging that of the individual motors in the same group. Finally, parameters of equivalent motors are calculated based on the relationship of transient impedance before and after aggregation, and the principle that active and reactive power loads are equal before and after aggregation. Simulation results show that the proposed method can improve the precision of simulation

Neural Substrates of Practice Structure That Support Future Off-Line Learning

Off-line learning is facilitated when motor skills are acquired under a random practice schedule and retention suffers when a similar set of motor skills are practiced under a blocked schedule. The current study identified the neural correlates of a random training schedule while participants learned a set of four-element finger sequences using their nondominant hand during functional magnetic resonance imaging. A go/no go task was used to separately probe brain areas supporting sequence preparation and production. By the end of training, the random practice schedule, relative to the block schedule, recruited a broad premotor–parietal network as well as sensorimotor and subcortical regions during both preparation and production trials, despite equivalent motor performance. Longitudinal analysis demonstrated that preparation-related activity under a random schedule remained stable or increased over time. The blocked schedule showed the opposite pattern. Across individual subjects, successful skill retention was correlated with greater activity at the end of training in the ipsilateral left motor cortex, for both preparation and production. This is consistent with recent evidence that attributes off-line learning to training-related processing within primary motor cortex. These results reflect the importance of an overlooked aspect of motor skill learning. Specifically, how trials are organized during training—with a random schedule—provides an effective basis for the formation of enduring motor memories, through enhanced engagement of core regions involved in the active preparation and implementation of motor programs.

Vestibular System May Provide Equivalent Motor Actions Regardless of the Number of Body Segments Involved in the Task

The vestibulospinal system likely plays an essential role in motor equivalence—the ability to reach the desired motor goal despite intentional or imposed changes in the number of body segments involved in the task. To test this hypothesis, we compared the ability of healthy subjects and patients with unilateral vestibular lesions (surgical acoustic neuroma resection 0.6 to 6.7 yr before the study) to maintain either the same hand position or the same trajectory of within arm reach movements while flexing the trunk, in the absence of vision. In randomly selected trials, the trunk motion was prevented by an electromagnetic device. Healthy subjects were able to preserve the hand position or trajectory by modifying the elbow and shoulder joint rotations in a condition-dependent way, at a minimal latency of about 60 ms after the trunk movement onset. In contrast, six of seven patients showed deficits in the compensatory angular modifications at least in one of two tasks so that 30–100% of the trunk displacement was not compensated and thus influenced the hand position or trajectory. Results suggest that vestibular influences evoked by the head motion during trunk flexion play a major role in maintaining the consistency of arm motor actions in external space despite changes in the number of body segments involved. Our findings also suggest that despite long-term plasticity in the vestibular system and related neural structures, unilateral vestibular lesion may reduce the capacity of the nervous system to achieve motor equivalence.