Can the structure of motor variability predict learning rate?

Recent studies show that motor variability is actively regulated as an exploration tool to promote learning in reward-based tasks. However, its role in learning processes during error-based tasks, when a reduction of the motor variability is required to achieve good performance, is still unclear. In this study, we hypothesized that error-based learning not only depends on exploration but also on the individuals’ ability to measure and predict the motor error. Previous studies identified a less auto-correlated motor variability as a higher ability to perform motion adjustments. Two experiments investigated the relationship between motor learning and variability, analyzing the long-range autocorrelation of the center of pressure fluctuations through the score of a Detrended Fluctuation Analysis in balance tasks. In Experiment 1, we assessed the relationship between variability and learning rate using a standing balance task. Based on the results of this experiment, and to maximize learning, we performed a second experiment with a more difficult sitting balance task and increased practice. The learning rate of the 2 groups with similar balance performances but different scores was compared. Individuals with a lower score showed a higher learning rate. Because the scores reveal how the motor output changes over time, instead of the magnitude of those changes, the higher learning rate is mainly linked to the higher error sensitivity rather than the exploration strategies. The results of this study highlight the relevance of the structure of output motor variability as a predictor of learning rate in error-based tasks

Tests to measure core stability in laboratory and field settings: reliability and correlation analyses

Although core stability (CS) has been assessed through many different tests, the relationships among them are currently unknown. The main objective was to analyse the relationship between five representative tests used to assess CS in: i) laboratory settings: Sudden Loading Test (SLT) and Stable and Unstable Sitting Test (SUST); ii) field settings: Biering-Sorensen Test (BST), Three-Plane Core Strength Test (TPCT) and Double-leg Lowering Test (DLLT). The reliability of these tests was also examined. Thirty-three recreationally active males performed the tests twice. The relationship between all variables was examined using Pearson-correlation coefficient in those variables with a good reliability. Only stiffness and angular displacement in the SLT, dynamic unstable tasks in the SUST and the holding-time in the BST showed good reliability (ICC: 0.63-0.91; typical error: 9.8%-21.0%). Few and low correlations were observed between the SLT, SUST and BST. Despite finding several significant correlations among the dynamic unstable tasks of the SUST (r≥0.807; p<0.01), no correlations were found between the loading directions of the SLT. The absence of correlations between these tests suggests that CS measurements are not generalisable, as they probably assess different dimensions of CS, or in the case of the BST, a different capacity (i.e. trunk extensor endurance)

EFFECT OF PERFORMANCE SPEED ON THE KINEMATICS AND KINETICS OF TWO TRUNK AND HIP STRENGTHENING EXERCISES

The aim of this work was to study the effect of speed on the sit-up (SU) and leg raising-lowering (LRL) exercise technique. Seventeen subjects volunteered to participate, performing at 3 cadences. Video 3D analysis was conducted and ground reaction forces were record. The anterior-posterior displacement of the centre of pressure (COP) and mean range of motion (ROM) for 6 angles were calculated. Results indicate that when SU speed increases, hip and knee ROM increase, while there is a decrease in the upper trunk flexion. In the LRL there is a decrease in the pelvic tilt and hip angle, and an increase in the knee angle. It seems that in higher speed exercises, subjects modified their technique to keep up with the cadence. Coaches and trainers should control the subjects’ technique during the execution of these high speed exercises

The role of motor variability in motor control and learning depends on the nature of the task and the individual’s capabilities

Recent studies have found that motor variability is actively regulated as an exploration tool to promote learning in reward and error-based tasks. Based on this functional role of variability, several researches have manipulated motor variability by practicing in order to maximize learning processes. However, the effectiveness of such variable practice as a tool to improve motor performance has shown several controversial results. The present work reviews how the interaction between the features of individuals with different motor capabilities (i.e. experience and brain disorders) and task constraints modulates the relation between motor variability and motor control and learning. Examining how the process of skill learning can be improved by the variability modulation according to individuals’ is not only of theoretical interest, but may also have several practical implications in motor learning and neuro-rehabilitation.Estudios recientes han demostrado que la variabilidad motora es activamente regulada como herramienta de exploración con objeto de incrementar el rendimiento motor tanto en tareas de aprendizaje basadas en la aplicación de recompensas como en la percepción del error. Basándose en este rol funcional de la variabilidad, varios investigadores han manipulado la variabilidad motora al practicar para maximizar los procesos de aprendizaje motor. Sin embargo, la efectividad de la práctica variable como herramienta para la mejora de la ejecución motora, ha mostrado resultados contradictorios en la literatura científica. El presente trabajo revisa cómo la interacción entre las características de individuos con diferentes capacidades motrices (i.e. experiencia y alteraciones neurológicas) y las características de las tareas modulan la relación entre la variabilidad motora, el control y el aprendizaje motor. El estudio de cómo los procesos de aprendizaje motor pueden ser mejorados mediante la manipulación de la carga de variabilidad al practicar no tiene sólo un interés teórico, sino que puede tener implicaciones prácticas en relación al aprendizaje motor o la neuro-rehabilitación

Differences in conditions of employment between sport managers with and without degree in physical activity and sport sciences

Objetivo: Analizar las diferencias laborales existentes entre los gestores deportivoscon estudios universitarios relacionados con las Ciencias de la Actividad Física y el Deporte respecto a los que no tienen esta titulación. Material y métodos: La muestra estuvo compuesta por 268gestores que desarrollan su actividadprincipal en centros deportivosen España (=34,38 años; DT=6,68). Se segmentó la muestra en dos grupos: profesionales con titulación Universitariaen Ciencias de la Actividad Física y el Deporte (n=104) y; profesionales que no poseíanesta titulación (n=164).Resultados:Los titulados universitarios son significativamente (p2.000 m2). Además,presentan una mayor intención de abandono de la empresa o del sector. Por el contrario, la formación no es un factor determinante en el género de los sujetos o en la cantidad de salario mensual percibido. Conclusiones:Para evitar el modelo de intrusismo desleal que incorpora a gestores deportivos poco cualificados y perjudica la imagen y derecho de los profesionales con titulación, se precisa de una adecuada regulación de favor del profesional con titulación de Ciencias de la Actividad Física y el Deporteen España que aglutine los mismos criterios.Esto ayudaría a las organizaciones deportivas a fidelizar a su personal con titulación universitaria en Ciencias de la Actividad Física y el Deporte.ObjectiveAnalyze existing in bachelor ́s degree labor differences between managers with college sports related Sciences of Physical Activity and Sport compared to those without this degree. Methods:The sample composed by268 managers who carry out their main activity in sports centers in Spain(=34.38 years, SD=6.68). The sample was segmented into two groups: professional that are graduates in Sport Sciences Degree (n=104) and, professionals who did not have this degree (n=164). Results:Graduates are significantly (p2,000 m2). Also, they have a higher intention to leave the company or the working sector. On the contrary, education is not a determining factor in the gender of the subjects or in the monthly salary. Conclusions:In order to avoid the unfair professional intrusion model that incorporates low-skilled managers and damage the image and rights of managers with university degree, a proper regulation that gathers the same criteria of the professional qualifications of Sciences of Physical Activity and Sport in Spain is required. This would help to sports organizations to retain their staff with university degree in Sciences of Physical Activity and Sport

Reliability of the Star Excursion Balance Test and Two New Similar Protocols to Measure Trunk Postural Control

Background: Although the Star Excursion Balance test (SEBT) has shown a good intrasession reliability, the intersession reliability of this test has not been deeply studied. Furthermore, there is an evident high influence of the lower limbs in the performance of the SEBT, so even if it has been used to measure core stability, it is possibly not the most suitable measurement. Objective: (1) To assess the absolute and relative between-session reliability of the SEBT and 2 novel variations of this test to assess trunk postural control while sitting, ie, the Star Excursion Sitting Test (SEST) and the Star Excursion Timing Test (SETT); and (2) to analyze the relationships between these 3 test scores. Design: Correlational and reliability testeretest study. Setting: Controlled laboratory environment. Participants: Twenty-seven physically active men (age: 24.54 3.05 years). Method: Relative and absolute reliability of the SEBT, SEST, and SETT were calculated through the intraclass correlation coefficient (ICC) and standard error of measurement (SEM), respectively. A Pearson correlation analysis was carried out between the variables of the 3 tests. Main Outcome Measures: Maximum normalized reach distances were assessed for different SEBT and SEST directions. In addition, composite indexes were calculated for SEBT, SEST, and SETT. Results: The SEBT (dominant leg: ICC ¼ 0.87 [0.73-0.94], SEM ¼ 2.12 [1.66-2.93]; nondominant leg: ICC ¼ 0.74 [0.50-0.87], SEM ¼ 3.23 [2.54-4.45]), SEST (ICC ¼ 0.85 [0.68-0.92], SEM ¼ 1.27 [1.03-1.80]), and SETT (ICC ¼ 0.61 [0.30-0.80], SEM ¼ 2.31 [1.82-3.17]) composite indexes showed moderate-to-high 1-month reliability. A learning effect was detected for some SEBT and SEST directions and for SEST and SETT composite indexes. No significant correlations were found between SEBT and its 2 variations (r .366; P > .05). A significant correlation was found between the SEST and SETT composite indexes (r ¼ .520; P > .01). Conclusions: SEBT, SEST, and SETT are reliable field protocols to measure postural control. However, whereas the SEBT assesses postural control in single-leg stance, SEST and SETT provide trunk postural control measures with lower influence of the lowerlimbs

Reliability assessment and correlation analysis of 3 protocols to measure trunk muscle strength and endurance

Different methods have been developed to quantify trunk muscle strength and endurance. However, some important protocol characteristics are still unclear, hindering the selection of the most suitable tests in each specific situation. The aim of this study was to examine the reliability and the relationship between 3 representative tests of the most common type of protocols used to assess trunk muscle strength and endurance. Twenty-seven healthy men performed each test twice spaced 1 month apart. Trunk strength and endurance were evaluated with an isokinetic dynamometer and 2 field tests including Biering-Sørensen test and Flexion–rotation trunk test. All tests showed a good relative consistency (intraclass correlation coefficient [ICC]> 0.75), except for the isokinetic endurance variables which had low–moderate reliability (0.37 0.65). Absolute reliability seemed slightly better in the isokinetic protocol than in the field tests, which showed about 12% of test–retest score increase. No significant correlations were found between test scores. After a familiarisation period for the field tests, the 3 protocols can be used to obtain reliable measures of trunk muscle strength and endurance. Based on the correlation analysis, these measures are not related, which highlights the importance of selecting the most suitable trunk test for each situation

Observational Screening Guidelines and Smartphone Accelerometer Thresholds to Establish the Intensity of Some of the Most Popular Core Stability Exercises

The lack of training load control, mainly exercise intensity, is one of the main limitations of core stability (CS) programs, which makes the training individualization and the analysis of the dose-response relationship difficult. The objectives of this study were to assess the inter-and intra-rater agreement when using new observational screening guidelines to decide if a core stability exercise represents an adequate training intensity level for a given participant. Besides, the relationship between experts' ratings based on these criteria and pelvic accelerations recorded with a smartphone accelerometer was also analyzed. Ten healthy physically active participants with a smartphone accelerometer placed on their pelvis were video-taped while performing a progression of seven variations of the front bridge, back bridge, side bridge and bird-dog exercises. Two expert and four non-expert raters watched the videos and used the observational screening guidelines to decide for each exercise variation if it represented an adequate training intensity level or not. In order to analyze the inter-and intra-rater agreement, several Kappa (κ) statistics were used. Receiver operating characteristic (ROC) curves to explore if the accelerometry allowed to establish pelvic acceleration thresholds representing the minimum level of exercise intensity for CS training. Cut-off acceleration values were calculated balancing sensitivity (Se) and 1-specifity (1-Sp) indexes (i.e., Youden index) or minimizing 1-Sp. The intra-and inter-rater analysis showed a substantial-high level of agreement with a prevalence-adjusted bias-adjusted Kappa > 0.69. The ROC curves showed that the acceleration thresholds for the bridging exercises were very similar, with global cut-off values of 0.35 m/s2 (Se = 82%; 1-Sp = 15%) when using the Youden Index and of 0.50 m/s2 when minimizing 1-Sp (Se = 31%), whilst the bird-dog exercise showed lower cut-off values (Youden Index: 0.21 m/s2, Se = 90%, 1-Sp = 16%; minimizing 1-Sp: 0.32 m/s2, Se = 40%). Overall, this study provides observational screening guidelines and smartphone accelerometer thresholds to facilitate the decision-making process when setting the intensity of some of the most popular core stability exercises in young physically active individual