Association Between Motor Competence and Percentage of Body Fat in Late Childhood: Comparing Proficiency in Fundamental Motor Skills and Advanced Movement Skills.

To solve the problem of a weakening relationship between motor competence and body adiposity from late childhood to adolescence, we defined and utilized advanced movement skills (AMS) characterized by higher biomechanical, physiological, and cognitive processing demands compared with fundamental motor skills (FMS). As a cross-sectional study, the proficiency in FMS and AMS for participants (43 boys and 45 girls) aged 9-12 years was measured by the Bruininks-Oseretsky Test of Motor Proficiency-Second Edition (BOT-2) and Test of Advanced Movement Skills (TAMS), respectively. Density plots and skewness of scoring distributions between assessments were inspected to examine test scalability.

Goal-Oriented Optimization of Dynamic Simulations to Find a Balance between Performance Enhancement and Injury Prevention during Volleyball Spiking.

Performance enhancement and injury prevention are often perceived as opposite sides of a coin, where focusing on improvements of one leads to detriment of the other. In this study, we used physics-based simulations with novel optimization methods to find participant-specific, whole-body mechanics of volleyball spiking that enhances performance (the peak height of the hitting hand and its forward velocity) while minimizing injury risk. For the volleyball spiking motion, the shoulder is the most common injury site because of the high mechanical loads that are most pronounced during the follow-through phase of the movement.

Biomechanics of hang-time in volleyball spike jumps.

Objective: This study examined whether "hang", an extended period of greatly reduced or zero vertical velocity of the head and trunk created by inter-segmental interactions, would be seen during skilled volleyball player spike jumps.

Method: Fifteen skilled volleyball hitters (eight men and seven women, age 23.26 ± 3.

Muscle activity and balance control during sit-to-stand across symmetric and asymmetric initial foot positions in healthy adults.

Background: Rising from a sit to a stand has biomechanical factors that are dependent on initial foot position. Little is known about the effect of initial foot position on leg muscle activation patterns during a sit-to-stand and balance maintenance of stance after a sit-to-stand.

Research Question: What are the effects of different symmetric and asymmetric initial foot positions on leg muscle activation patterns and balance during and after a sit-to-stand?

Methods: Three symmetric (neutral; both ankles positioned under the knees at a 90° flexion; one-third; and two-thirds foot length posterior to neutral) and three asymmetric (neutral non-dominant leg with one-third back dominant leg, neutral non-dominant with two-thirds back dominant leg, and one-third back non-dominant leg with two-thirds back dominant leg) initial foot positions were tested.

Ontogenetic changes in foot strike pattern and calcaneal loading during walking in young children.

The assumption that the morphology of the human calcaneus reflects high and cyclical impact forces at heel strike during adult human walking has never been experimentally tested. Since a walking step with a heel strike is an emergent behavior in children, an ontogenetic study provides a natural experiment to begin testing the relationship between the mechanics of heel strike and calcaneal anatomy. This study examined the ground reaction forces (GRFs) of stepping in children to determine the location of the center of pressure (COP) relative to the calcaneus and the orientation and magnitude of ground reaction forces during foot contact.

Effect of wheelchair design on wheeled mobility and propulsion efficiency in less-resourced settings.

Background: Wheelchair research includes both qualitative and quantitative approaches, primarily focuses on functionality and skill performance and is often limited to short testing periods. This is the first study to use the combination of a performance test (i.e.

Sirsasana (headstand) technique alters head/neck loading: Considerations for safety.

Background: This study examined the weight-bearing responsibility of the head and neck at moments of peak force during three headstand techniques.

Methods: Three matched groups of 15 each (18-60 years old) were formed based upon lower limb entry/exit technique: symmetrical extended, symmetrical flexed, and asymmetrical flexed. All 45 practitioners performed 3 headstands.

Age- and activity-related differences in the mechanisms underlying maximal power production in young and older adults.

The purpose of this study was to examine the interactions between aging, activity levels and maximal power production during cycling. Participants were divided into younger adults (YA), older active adults (OA,) and older sedentary adults (OS). Absolute maximum power was significantly greater in YA compared with OS and OA; no differences were found between OA and OS.

Effects of strategy use on children's motor performance in a continuous timing task.

The purposes of this study were to associate age-related performance deficits in children with the use of recall strategies and to determine whether children who performed poorly in cycling would benefit from learning a recall strategy. In Experiment 1, 18 younger children (ages 5-7years) and 18 older children (ages 8-10 years) were asked to recall selected pedaling cadences. The majority of the older children used strategies and performed with less error than the younger children.

Effectiveness of auditory and visual sensory feedback for children when learning a continuous motor task.

Accuracy in control of continuous motor tasks has been reported to be a function of age as well as sensory feedback, with auditory sensory feedback being more effective for adults than visual sensory feedback. In contrast, there are conflicting reports regarding the effectiveness of sensory feedback for children. The present purpose was to examine whether auditory sensory feedback was beneficial for children learning a continuous cycling task.

Effect of relative changes in anthropometry during childhood on muscular power production in pedaling: a biomechanical simulation.

When performing skillful movement muscular and nonmuscular forces act in concert to produce a resultant force that complies with the goal of the task. Nonmuscular forces are directly dependent on the anthropometry of the performer. The purpose of this study was to determine the effect of age-related changes in relative anthropometric characteristics between 5 and 10 years of age on muscular power production during pedaling.

Age-related differences in adaptation during childhood: the influences of muscular power production and segmental energy flow caused by muscles.

Acquisition of skillfulness is not only characterized by a task-appropriate application of muscular forces but also by the ability to adapt performance to changing task demands. Previous research suggests that there is a different developmental schedule for adaptation at the kinematic compared to the neuro-muscular level. The purpose of this study was to determine how age-related differences in neuro-muscular organization affect the mechanical construction of pedaling at different levels of the task.

The role of segmental mass and moment of inertia in dynamic-contact task construction.

The authors examined whether differences between children and adults in the application of muscle forces during a dynamic-contact task (cycling) can be attributed to children's relatively lower segmental mass and moment of inertia. They examined pedal-force construction as adults and younger and older children (n = 7 in each group), with and without mass added to their limbs, pedaled an appropriately scaled bicycle ergometer. When mass was added to their limbs, children adjusted muscular forces on the pedal in a way that began to approach the pattern demonstrated by adults.

Adapting to changing task demands: variability in children's response to manipulations of resistance and cadence during pedaling.

Reduction in performance variability is characteristic of skill acquisition during childhood. Less understood is the role of variability in adaptive skill. The purpose of this study was to determine children's capacity for adapting to changing task requirements.

Postural response in older adults with different levels of functional balance capacity.

Background And Aims: Aging is frequently accompanied by a deterioration in postural control, but it is not clear whether the primary contributor is increasing age or a progressive loss of functional balance capacity. The purpose of this study was to test the hypothesis that functional balance capacity contributes more than age to changes in postural response in the elderly.

Methods: The study considered 3 groups of healthy young, and functionally-stable and functionally-unstable older adults (N = 16 each group).

The effect of cane use on the compensatory step following posterior perturbations.

Objective: The compensatory step is a critical component of the balance response and is impaired in older fallers. The purpose of this research was to examine whether utilization of a cane modified the compensatory step response following external posterior perturbations.

Design: Single subject withdrawal design was employed.

An emerging postural response: is control of the hip possible in the newly walking child?

Previous researchers have proposed that because of their slow muscle-response latencies, 1- to 2-year-old children are unable to control hip-dominant postural responses when responding to balance threats (G. McCollum & T. Leen, 1989).

The development of contact force construction in the dynamic-contact task of cycling [corrected].

Purposeful movement requires that an individual produce appropriate joint torques to accelerate segments, and when environmental contact is involved, to develop task-appropriate contact forces. Developmental research has been confined largely to the mastery of unconstrained movement skills (pointing, kicking). The purpose of this study was to study the developmental progression that characterizes the interaction of muscular and non-muscular forces in tasks constrained by contact with the environment.

Age-related differences in lower extremity power after support surface perturbations.

Objectives: The purpose of this study was to examine a comprehensive measure relating to the ability to generate, absorb, and transfer mechanical energy introduced by a perturbation. It was hypothesized that this measure would reveal age-related differences leading to different balance recovery responses (i.e.