Johannes P van Dijk

Learn More
To obtain more insight into the changes in mean muscle fiber conduction velocity (MFCV) during sustained isometric exercise at relatively low contraction levels, we performed an in-depth study of the human tibialis anterior muscle by using multichannel surface electromyogram. The results show an increase in MFCV after an initial decrease of MFCV at 30 or(More)
Studies on isolated muscle and resting man have demonstrated that altering CO2 stores influences intracellular lactate production and/or tissue lactate release. In the present project, subjects (N = 6) performed steady-state exercise for 30 min while inspiring 0, 2, 4, or 6% CO2 and 21% O2. They were tested on eight occasions, four at 50% and four at 65%(More)
Recently, high-density surface EMG electrode grids and multi-channel amplifiers became available for non-invasive recording of human motor units (MUs). We present a way to decompose surface EMG signals into MU firing patterns, whereby we concentrate on the importance of two-dimensional spatial differences between the MU action potentials (MUAPs). Our method(More)
Responsive outcome measures are needed to follow the disease status of Duchenne muscular dystrophy (DMD) patients, as new therapeutic approaches become available for affected boys. Quantitative muscle ultrasound (QMUS) is potentially an attractive follow up tool for DMD because it reflects the severity of the dystrophic process without the need for invasive(More)
OBJECTIVE Muscle ultrasound is capable of visualizing muscle movements. Recent improvements in ultrasound technology have raised the question whether it is also possible to detect small-scale spontaneous muscle activity such as denervation. In this study we investigated the ability of dynamic muscle ultrasound to detect fibrillations. METHODS Eight(More)
OBJECTIVES To compare the effect of endplate-targeted injections of a low Botulinum neurotoxin type A (BoNT-A) dose with that of injections at defined distances from the motor endplate zone. METHODS In eight healthy volunteers, the main endplate zones of the right and left extensor digitorum brevis (EDB) muscles were localized using high-density surface(More)
The objective of this study was to systematically characterize motor units (MUs) of the musculature of the lower face. MU endplate positions and principal muscle fiber orientations relative to facial landmarks were identified. This was done by the analysis of motor unit action potentials (MUAPs) in the surface electromyogram. Thirteen specially trained,(More)
OBJECTIVE To present a motor unit number estimation (MUNE) technique that resolves alternation by means of high-density surface EMG. METHODS High-density surface EMG, using 120 EMG channels simultaneously, is combined with elements of the increment counting technique (ICT) and the multiple-point stimulation technique. Alternation is a major drawback in(More)
High-density multichannel electromyography (EMG) recordings add spatial information to the temporal information content of the surface EMG (sEMG) signal. This study explores the potential value of such multichannel information at a single motor unit level, in particular for the improvement of motor unit number estimation (MUNE) techniques. It is shown that(More)