Jurriaan H. de Groot

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OBJECTIVE The development of a thorax-fixed regression model for the shoulder which statistically predicts the orientation of the clavicle and the scapula from the humerus orientation. BACKGROUND The application of three-dimensional position recording systems to the shoulder mechanism is limited to laboratory conditions. Studies in the field of ergonomics(More)
Sudden stretch of active muscle typically results in two characteristic electromyographic responses: the short latency M1 and the long latency M2. The M1 response originates from the monosynaptic Ia afferent reflex pathway. The M2 response is less well understood and is likely a compound response to different afferent inputs mediated by spinal and(More)
To capture prey, chameleons ballistically project their tongues as far as 1.5 body lengths with accelerations of up to 500 m s(-2). At the core of a chameleon's tongue is a cylindrical tongue skeleton surrounded by the accelerator muscle. Previously, the cylindrical accelerator muscle was assumed to power tongue projection directly during the actual fast(More)
OBJECTIVE To assess the reliability of force direction dependent EMG parameters in shoulder muscles for future clinical research. DESIGN EMG measurements of shoulder muscles including the rotator cuff were performed during isometrical external loading in various directions covering 360 degrees in a plane perpendicular to the humeral axis. BACKGROUND(More)
The long latency M2 electromyographic response of a suddenly stretched active muscle is stretch duration dependent of which the nature is unclear. We investigated the influence of the group II afferent blocker tizanidine on M2 response characteristics of the m. flexor carpi radialis (FCR). M2 response magnitude and eliciting probability in a group of(More)
Background and Objective Favorable prognosis of the upper limb depends on preservation or return of voluntary finger extension (FE) early after stroke. The present study aimed to determine the effects of modified constraint-induced movement therapy (mCIMT) and electromyography-triggered neuromuscular stimulation (EMG-NMS) on upper limb capacity early(More)
BACKGROUND AND PURPOSE It is largely unknown how adaptive motor control of the paretic upper limb contributes to functional recovery after stroke. This paucity of knowledge emphasizes the need for longitudinal 3-dimensional (3D) kinematic studies with frequent measurements to establish changes in coordination after stroke. A portable 3D kinematic setup(More)
OBJECTIVE The objective of this study is to determine the relation between arm load and the three-dimensional shoulder orientations. BACKGROUND Analysis of a musculo-skeletal system by means of an inverse dynamical simulation requires postural data of the bony elements involved. For the shoulder, the positions of the clavicle and the scapula are difficult(More)
In a static force task the electromyographic level of 14 shoulder muscles including 3 rotator cuff muscles was related to force direction. Surface and wire electrodes were used. The force direction of maximal electromyography (principal action) was identified for every muscle. The principal action expresses the function of a muscle in a special situation.(More)
Muscles behave as elastic springs during the initial strain phase, indicated as short range stiffness (SRS). Beyond a certain amount of strain the muscle demonstrates a more viscous behavior. The strain at which the muscle transits from elastic- to viscous-like behavior is called the elastic limit and is believed to be the result of breakage of(More)