1,023 research outputs found
Muscle temperature has a different effect on force fluctuations in young and older women
No full textObjective: To investigate the effect of muscle temperature on force fluctuations during isometric contractions in young and older females. Methods: Fifteen young and 11 older subjects performed 3 · 30-s long submaximal isometric ankle dorsi-flexions (5%, 10%, and 15% of the maximal force). Tibialis anterior muscle temperature was monitored with an intramuscular probe and manipulated to obtain a cold, control, and warm condition. The coefficient of variation (CofV) and the relative power in the frequency bands 0–3 Hz (low), 4–6 Hz (middle), and 8–12 Hz (high) of the force signal were computed to characterise steadiness. Intramuscular EMG signals were recorded from the tibialis anterior muscle to assess motor unit discharge pattern. Results: CofV was higher in the older than in the young subjects (P < 0.001) in all conditions. In the older group only, CofV increased with cooling with respect to control temperature (P < 0.001), whereas in the young group only, relative power of force fluctuations at high frequency decreased with cooling. Motor unit discharge rate and inter-pulse interval variability were not different between groups and across temperatures. Conclusions: The findings indicate a different effect of temperature on the ability to maintain constant force in young and older subjects. Significance: These results highlight the risk of further impairment to the motor control of older individuals with varying temperature
Surface EMG crosstalk evaluated from experimental recordings and simulated signals
No full textSummary
Objectives:
Surface EMG crosstalk is the EMG signal detected over a non-active muscle and generated by a nearby muscle. The aim of this study was to analyze the sources of crosstalk signals in surface EMG recordings and to discuss methods proposed in the literature for crosstalk quantification and reduction.
Methods:
The study is based on both simulated and experimental signals. The simulated signals are generated by a structure based surface EMG signal model. Signals were recorded with both intramuscular and surface electrodes and single motor unit surface potentials were extracted with the spike triggered averaging approach. Moreover, surface EMG signals were recorded from electrically stimulated muscles.
Results:
From the simulation and experimental analysis it was clear that the main determinants of crosstalk are non-propagating signal components, generated by the extinction of the intracellular action potentials at the tendons. Thus, crosstalk signals have a different shape with respect to the signals detected over the active muscle and contain high frequency components.
Conclusions:
Since crosstalk has signal components different from those dominant in case of detection from near sources, commonly used methods to quantify and reduce crosstalk, such as the cross-correlation coefficient and high-pass temporal filtering, are not reliable. Selectivity of detection systems must be discussed separately as selectivity with respect to propagating and non-propagating signal components. The knowledge about the origin of crosstalk signal constitutes the basis for crosstalk interpretation, quantification, and reduction.</jats:p
T. N. D. Mettinger. No Graven Image ? Israelite Aniconism in its Ancient Eastern Context
No full textCaquot André. T. N. D. Mettinger. No Graven Image ? Israelite Aniconism in its Ancient Eastern Context. In: Revue de l'histoire des religions, tome 213, n°1, 1996. pp. 93-95
The effect of experimental muscle pain on motor unit firing rate and conduction velocity
No full textT. N. D. Mettinger. No Graven Image ? Israelite Aniconism in its Ancient Eastern Context
No full textCaquot André. T. N. D. Mettinger. No Graven Image ? Israelite Aniconism in its Ancient Eastern Context. In: Revue de l'histoire des religions, tome 213, n°1, 1996. pp. 93-95
Beschryving van's Graven-hage.
No full text"Costumen van's Graven-hage": 78 p. at end of v. [2]v. 2 pub. by J. de Cros's Graven'hage.Title vignette; initials; tail-pieces. Parts 1 and 2 of v. 1 have added t.-p., engr. and are paged continuously.Mode of access: Internet
Conditioning of heteronymous H-reflex in human temporalis muscle by stimulation of perioral afferents
No full textLow-Threshold Motor Unit Twitch Force and Conduction Velocity Following Sub-Maximal Fatiguing Contractions
No full text
Two-dimensional spatial distribution of surface mechanomyographical response to single motor unit activity
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