Richard E. A. Van Emmerik

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The nature of coordination changes and stability features in the relative phase dynamics of the trunk were examined in seven healthy subjects, while walking velocity on a treadmill was gradually increased and decreased. Predictions from Schöner et al (J. Theor. Biol. 142, 359-391, 1990) regarding transition mechanisms in quadrupedal walking generalized to(More)
The present study is aimed at investigating changes in the coordination of arm and leg movements in young healthy subjects. It was hypothesized that with changes in walking velocity there is a change in frequency and phase coupling between the arms and the legs. In addition, it was hypothesized that the preferred frequencies of the different coordination(More)
Current research in nonlinear dynamics and chaos theory has challenged traditional perspectives that associate high variability with performance decrement and pathology. It is argued that variability can play a functional role in postural control and that reduction of variability is associated with changes in balance with aging and neurological disease.
The aim of this study was to examine the influence of skill of expert triple jumpers on the coordination variability of lower extremity intra-limb couplings. In contrast to the traditional motor learning perspective, we hypothesized that as skill and thus performance increases, movement coordination variability will also increase. Three-dimensional(More)
The purpose of this study was to determine if gender differences exist in the variability of various lower extremity (LE) segment and joint couplings during an unanticipated cutting maneuver. 3-D kinematics were collected on 24 college soccer players (12 M, 12 F) while each performed the cutting maneuver. The following intralimb couplings were studied:(More)
Head turning after release from the midline and the Moro response to a full-body drop in 15 full-term newborns lying supine on a custom-built platform was studied. While the lateral bias for head turning was not as pronounced as for the Moro response, it was still assumed in the ratio of 2 (right):1 (left) as predicted by Previc (1991). Onset latency and(More)
Studies have suggested that proper postural control is essential for the development of reaching. However, little research has examined the development of the coordination between posture and manual control throughout childhood. We investigated the coordination between posture and manual control in children (7- and 10-year-olds) and adults during a(More)
The effect of practice on limb kinematics in a dart-throwing task was examined to test three current hypotheses regarding limb control: trajectory formation; end-point control; and coordinated joint-space control. Practice was given to both the relatively well-practiced dominant ant the relatively unpracticed nondominant limbs of 5 male subjects to permit(More)
The relation between age-specific postural instability and the detection of stability boundaries was examined. Balance control was investigated under different visual conditions (eyes open/closed) and postural orientations (forward/backward lean) while standing on a force platform. Dependent variables included center of pressure variability and the(More)
Postural instability is a major problem in patients with Parkinson's disease (PD). We examined balance control in PD by using center of pressure (CP) variability and time-to-contact to investigate boundary relevant postural control behavior under quiet stance leaning conditions. Postural orientation was manipulated by having patients (n = 10) and healthy(More)