The aim of this study was to quantify internal joint moments of the lower limb during vertical jumping and the weightlifting jerk to improve awareness of the control strategies and correspondence between these activities, and to facilitate understanding of the likely transfer of training effects. Athletic men completed maximal unloaded vertical jumps (n = 12) and explosive push jerks at 40 kg (...

Acceleration profile generation for jerk limitation is a major issue in automated industrial applications like computer numerical control (CNC) machinery and robotics. The automation machinery dynamics should be kept as smooth as possible with suitable controllers where trajectory precision ensures quality while smoothness decreases machinery stress. During the operation of commercially availab...

Longitudinal height and weight data from 4649 Dutch twin pairs between birth and 2.5 years of age were analyzed. The data were first summarized into parameters of a polynomial of degree 4 by a mixed-effects procedure. Next, the variation and covariation in the parameters of the growth curve (size at one year of age, growth velocity, deceleration of growth, rate of change in deceleration [i.e., ...

During voluntary jaw clenching, a sharp tap to the menton of the mandible resulted in a transitory silent period (pause) in the electromyographic activity of the masseter and anterior temporalis muscles. Factors that could influence the duration of the silent period were studied, including direction and magnitude of the stimulus applied by the operator, the amount of muscular effort exerted by ...

A guest editorial on the multidirectional instability of the shoulder Introduction The multidirectional instability of the shoulder is a complex problem in terms of diagnosis and treatment. Distinct from multidirectional hyperlaxity, multidirectional instability has symptoms related with increased translations in more than one direction. Increased translation by the increased capsular ligamento...

BACKGROUND When the human body is introduced to a new motion or movement, it learns the placement of different body parts, sequential muscle control, and coordination between muscles to achieve necessary positions, and it hones this new skill over time and repetition. Previous studies have demonstrated definite differences in the smoothness of body movements with different levels of training, i...

When looking for help with a task at work, people turn to those best able to do the job. Right? Wrong. New research shows that work partners tend to be chosen not for ability but for likability. Drawing from their study encompassing 10,000 work relationships in five organizations, the authors have classified work partners into four archetypes: the competent jerk, who knows a lot but is unpleasa...