Mechanism for High-Precision Control of Movement at Maximum Output in the Vertical Jump Task.

Human movements are governed by a tradeoff between speed and accuracy. Previous studies that have investigated the tradeoff relationship in sports movements involving whole-body movements have been limited to examining the relationship from the perspective of competition-specific movements, and the findings on whether the relationship is valid have not been unified. Therefore, this study incorporated a vertical jump task with the introduction of a condition in which landing position control was added to evaluate the essence of a sports movement that requires both speed and accuracy.

Human Information Processing of the Speed of Various Movements Estimated Based on Trajectory Change.

Fitts' approach, which examines the information processing of the human motor system, has the problem that the movement speed is controlled by the difficulty index of the task, which the participant uniquely sets, but it is an arbitrary speed. This study rigorously aims to examine the relationship between movement speed and information processing using Woodworth's method to control movement speed. Furthermore, we examined movement information processing using an approach that calculates probability-based information entropy and mutual information quantity between points from trajectory analysis.

Estimating Information Processing of Human Fast Continuous Tapping from Trajectories.

Fitts studied the problem of information capacity and transfer in the speed-accuracy motor paradigm using a theoretical approach developed from Shannon and Weaver's information theory. The information processing (bit/s) estimated in Fitts' study is calculated from the movement time required to achieve the required task index of difficulty but is essentially different from Shannon's information entropy. Thus, we estimated the information entropy of multiple human movement trajectories and the mutual information among trajectories for the continuous aiming task in Fitts' paradigm.

Fitts' law when errors are not allowed: Quantification of reciprocating trajectories and estimating information processing.

There are circumstances in which humans are required to move in environments wherein accuracy should be maximized, such as golf putting or surgeons' hand movements during surgical procedures. Fitts' law expresses human movement by movement time and task difficulty, which is determined by one's distance from the target and the targets' size. Additionally, this law is considered as the most universal expression of human movement.

Difference Between Intentional and Reactive Movement in Side-Steps: Patterns of Temporal Structure and Force Exertion.

Intentional and reactive movements are dissimilar in terms of execution time. Previous studies reported that reactive movements are faster than intentional movements ("Bohr's law" or "Gunslinger effect"), however, these studies focused only on hand-reaching tasks, such as pressing buttons. No studies assessed whole-body movements involving movement of the center of mass (CoM).

Water Sensation During Passive Propulsion for Expert and Nonexpert Swimmers.

This study determined whether expert swimmers, compared with nonexperts, have superior movement perception and physical sensations of propulsion in water. Expert (national level competitors, n = 10) and nonexpert (able to swim 50 m in > 3 styles, n = 10) swimmers estimated distance traveled in water with their eyes closed. Both groups indicated their subjective physical sensations in the water.

Temporal coordination between ground reaction forces generated by leading and trailing limbs for propulsion during double stance phase in human walking.

Although it was reported that ground reaction forces (GRFs) are generated simultaneously by the leading and trailing limbs during the double stance phase, the finding was not examined by temporal analyses. Therefore, the purpose of the present study is to clarify how GRFs can act to propel the body in a forward direction during the double stance phase. GRFs were recorded during the double stance phase in eleven healthy volunteers.

Intersegmental dynamics of 3D upper arm and forearm longitudinal axis rotations during baseball pitching.

The shoulder internal rotation (IR) and forearm pronation (PR) are important elements for baseball pitching, however, how rapid rotations of IR and PR are produced by muscular torques and inter-segmental forces is not clear. The aim of this study is to clarify how IR and PR angular velocities are maximized, depending on muscular torque and interactive torque effects, and gain a detailed knowledge about inter-segmental interaction within a multi-joint linked chain. The throwing movements of eight collegiate baseball pitchers were recorded by a motion capture system, and induced-acceleration analysis was used to assess the respective contributions of the muscular (MUS) and interactive torques associated with gyroscopic moment (GYR), and Coriolis (COR) and centrifugal forces (CEN) to maximum angular velocities of IR (MIRV) and PR (MPRV).

Anticipation of elbow joint perturbation shortens the onset time of the reflex EMG response in biceps brachii and triceps brachii.

This study aimed to investigate the influence of the anticipation of a perturbation torque applied to extend the elbow joint on the onset time of reflex electromyogram (EMG) responses. A perturbation torque generated by an electromagnetic torque motor system was applied to the forearm of eleven subjects during trials. The trials were divided into an anticipated (AN) condition - perturbation torque applied after the auditory signal - and an unanticipated (UAN) condition - suddenly applied perturbation.

Modulation of elbow joint stiffness in a vertical plane during cyclic movement at lower or higher frequencies than natural frequency.

The purpose of the present study was to determine how joint stiffness during cyclic movement in a vertical plane is modulated at lower or higher frequencies than the natural frequency of the system. Five male subjects were instructed to swing their forearms rhythmically in a vertical plane under various frequency conditions (0.7-2.