Search Results

This study examined variability in throwing speed and spatial error to test the prediction of an inverted-U function (i.e., impulse-variability [IV] theory) and the speed-accuracy trade-off. Forty-five 9- to 11-year-old children were instructed to throw at a specified percentage of maximum speed (45%, 65%, 85%, and 100%) and hit the wall target. Results indicated no statistically significant differences in variable error across the target conditions (p = .72), failing to support the inverted-U hypothesis. Spatial accuracy results indicated no statistically significant differences with mean radial error (p = .18), centroid radial error (p = .13), and bivariate variable error (p = .08) also failing to support the speed-accuracy trade-off in overarm throwing. As neither throwing performance variability nor accuracy changed across percentages of maximum speed in this sample of children as well as in a previous adult sample, current policy and practices of practitioners may need to be reevaluated.

This study examined variability in kicking speed and spatial accuracy to test the impulse-variability theory prediction of an inverted-U function and the speed-accuracy trade-off. Twenty-eight 18- to 25-year-old adults kicked a playground ball at various percentages (50–100%) of their maximum speed at a wall target. Speed variability and spatial error were analyzed using repeated-measures ANOVA with built-in polynomial contrasts. Results indicated a significant inverse linear trajectory for speed variability (p < .001, η²= .345) where 50% and 60% maximum speed had significantly higher variability than the 100% condition. A significant quadratic fit was found for spatial error scores of mean radial error (p < .0001, η² = .474) and subject-centroid radial error (p < .0001, η² = .453). Findings suggest variability and accuracy of multijoint, ballistic skill performance may not follow the general principles of impulse-variability theory or the speed-accuracy trade-off.

Background: The objective was to examine changes of children’s time spent in sedentary, light physical activity, moderate to vigorous physical activity (MVPA), and estimated energy expenditure (EE) rates during weekdays and weekends across 3 years. Methods: An initial sample of 261 children’s (mean age = 7.81 y) 5-day physical activity and EE were assessed annually via accelerometry across 3 years using repeated-measures multivariate analysis of variance. The outcome variables were time spent in sedentary, light physical activity, MVPA, and kilocalories per day for weekdays and weekends. Results: A significant decrease in MVPA and EE occurred during weekdays across the 3 years (P = .01). Only the second-year data demonstrated an increase (+2.49 min) in weekend MVPA (P = .04). Children’s sedentary time during weekdays increased significantly in years 1 and 2 (P = .01), yet significantly decreased in the third year (−44.31 min). Children’s sedentary time during weekends significantly decreased in the first year (−27.31 min), but increased in the following 2 years (P = .01). Children’s light physical activity demonstrated a statistically significant increase in year 2 (+3.75 min) during weekdays (P = .05). Conclusions: Children’s MVPA and EE generally declined during weekdays but were maintained during weekends across a 3-year time span. Children may benefit most from weekday intervention strategies.

Generating consistent maximum ball velocity is an important factor for a baseball pitcher’s success. While previous investigations have focused on the role of the upper and lower extremities, little attention has been given to the trunk. In this study it was hypothesized that variations in pelvis and upper torso kinematics within individual pitchers would be significantly associated with variations in pitched ball velocity. Nineteen elite baseball pitchers were analyzed using 3-D high-speed motion analysis. For inclusion in this study, each pitcher demonstrated a variation in ball velocity of at least 1.8 m/s (range: 1.8–3.5 m/s) during his 10 fastball pitch trials. A mixed-model analysis was used to determine the relationship between 12 pelvis and upper torso kinematic variables and pitched ball velocity. Results indicated that five variables were associated with variations in ball velocity within individual pitchers: pelvis orientation at maximum external rotation of the throwing shoulder (p = .026), pelvis orientation at ball release (p = .044), upper torso orientation at maximum external rotation of the throwing shoulder (p = .007), average pelvis velocity during arm cocking (p = .024), and average upper torso velocity during arm acceleration (p = .035). As ball velocity increased, pitchers showed an increase in pelvis orientation and upper torso orientation at the instant of maximal external rotation of the throwing shoulder. In addition, average pelvis velocity during arm cocking and average upper torso velocity during arm acceleration increased as ball velocity increased. From a practical perspective, the athlete should be coached to strive for proper trunk rotation during arm cocking as well as strength and flexibility in order to generate angular velocity within the trunk for maximum ball velocity.

This cross-sectional study examined associations among motor skill competence (MSC) and health-related fitness (HRF) in youth. A convenient sample of 253 boys and 203 girls (aged 4–13 years) participated in the study. Associations among measures of MSC (throwing and kicking speed and standing long jump distance) and a composite measure of HRF (push-ups, curl-ups, grip strength and PACER test) across five age groups (4–5, 6–7, 8–9, 10–11 and 12–13 yrs.) were assessed using hierarchical regression modeling. When including all children, throwing and jumping were significantly associated with the composite HRF factor for both boys and girls (throw, t = 5.33; jump, t = 4.49) beyond the significant age effect (t = 4.98) with kicking approaching significance (t = 1.73, p = .08). Associations between throwing and kicking speed and HRF appeared to increase from early to middle to late childhood age ranges. Associations between jumping and HRF were variable across age groups. These results support the notion that the relationship between MSC and HRF performance are dynamic and may change across childhood. These data suggest that the development of object control skills in childhood may be important for the development and maintenance of HRF across childhood and into adolescence.

To reach the level of elite, most baseball pitchers need to consistently produce high ball velocity but avoid high joint loads at the shoulder and elbow that may lead to injury. This study examined the relationship between fastball velocity and variations in throwing mechanics within 19 baseball pitchers who were analyzed via 3-D high-speed motion analysis. Inclusion in the study required each one to demonstrate a variation in velocity of at least 1.8 m/s (range 1.8–3.5 m/s) during 6 to 10 fastball pitch trials. Three mixed model analyses were performed to assess the independent effects of 7 kinetic, 11 temporal, and 12 kinematic parameters on pitched ball velocity. Results indicated that elbow flexion torque, shoulder proximal force, and elbow proximal force were the only three kinetic parameters significantly associated with increased ball velocity. Two temporal parameters (increased time to max shoulder horizontal adduction and decreased time to max shoulder internal rotation) and three kinematic parameters (decreased shoulder horizontal adduction at foot contact, decreased shoulder abduction during acceleration, and increased trunk tilt forward at release) were significantly related to increased ball velocity. These results point to variations in an individual's throwing mechanics that relate to pitched ball velocity, and also suggest that pitchers should focus on consistent mechanics to produce consistently high fastball velocities. In addition, pitchers should strengthen shoulder and elbow musculature that resist distraction as well as improve trunk strength and flexibility to maximize pitching velocity and help prevent injury.

Examining the underlying processes that contribute to fundamental movement pattern development and their relationship to performance outcomes is essential to effectively promote competence and mastery. However, few studies have examined the associations between process-oriented movement assessments and performance. The purpose of this study was to hypothesize component developmental sequences for the landing phase of the standing long jump and test them via a pre-longitudinal screen with cross-sectional data from children and young adults. Component levels of the standing long jump landing were identified for shank, foot, and arm action on 347 children ages 4–12 years and 48 adults ages 18–25 years. Modal profile curves were plotted for each component across age groups. In addition, modal sequences, height, and mass were regressed against jump distance as a secondary method of developmental validation. Component level trajectories indicated sufficient evidence for developmental trends of each component. Explained variance in jump distance by sequences, height, and mass varied across age groups and sex. Our findings indicate the proposed component sequences for landing may demonstrate adequate developmental validity; however, longitudinal validation is needed. Landing patterns play an important role in standing long jump performance and warrant more attention in motor development research.