690 research outputs found
Investigation of motor unit recruitment during stimulated contractions of tibialis anterior muscle
No full textAutomatic localisation of innervation zones: a simulation study of the external anal sphincter
No full textTraumas of the innervation zone (IZ) of the external anal sphincter (EAS), e.g. during delivery, can promote the development of faecal incontinence. Recently developed probes allow high-resolution detection
of EMG signals from the EAS. The analysis of pelvic floor muscles by surface EMG (in particular, the estimation of the location of the IZ) has potential applications in the diagnosis and investigation of the mechanisms of incontinence.
An automatic method (based on matched filter approach) for the estimation of the IZ distribution of
EAS from surface EMG is discussed and tested using an analytical model of generation of EMG signals
from sphincter muscles. Simulations are performed varying length of the fibres, thickness of the mucosa,
position of the motor units, and force level. Different distributions of IZs are simulated.
The performance of the proposed method in the estimation of the IZ distribution is affected by surface
MUAP amplitude (as the estimation made by visual inspection), by mucosa thickness (performance
decreases when fibre length is higher) and by different MU distributions. However, in general the method
is able to identify the position of two IZ locations and can measure asymmetry of the IZ distribution. This
strengthens the potential applications of high density surface EMG in the prevention and investigation of
incontinence
Effects of Italian smoking regulation on rates of hospital admission for acute coronary events: a country-wide study.
No full textBACKGROUND: Several studies have reported a reduction in acute coronary events (ACEs) in the general population after the enforcement of smoking regulations, although there is uncertainty concerning the magnitude of the effect of such interventions. We conducted a country-wide evaluation of the health effects of the introduction of a smoking ban in public places, using data on hospital admissions for ACEs from the Italian population after the implementation of a national smoking regulation in January 2005.
METHODS AND FINDINGS: Rates of admission for ACEs in the 20 Italian regions from January 2002 to November 2006 were analysed using mixed-effect regression models that allowed for long-term trends and seasonality. Standard methods for interrupted time-series were adopted to assess the immediate and gradual effects of the smoking ban. Effect modification by age was investigated, with the assumption that exposure to passive smoking in public places would be greater among young people. In total, 936,519 hospital admissions for ACEs occurred in the Italian population during the study period. A 4% reduction in hospital admissions for ACEs among persons aged less than 70 years was evident after the introduction of the ban (Rate Ratio [RR], 0.96; 95% Confidence Interval [CI], 0.95-0.98). No effect was found among persons aged at least 70 years (RR 1.00; 95% CI 0.99-1.02). Effect modification by age was further suggested by analyses using narrower age categories.
CONCLUSIONS: Smoke-free policies can constitute a simple and inexpensive intervention for the prevention of cardiovascular diseases and thus should be included in prevention programmes
Assessment of average muscle fiber conduction velocity from surface EMG signals during fatiguing dynamic contractions
No full textA surface EMG generation model with multi-layer cylindrical description of the volume conductor
No full textWe propose a model for surface EMG signal generation with cylindrical description of the volume conductor. The model is more general and complete with respect to previous approaches. The volume conductor is described as a multi-layered cylinder in which the source can be located either along the longitudinal or the angular direction, in any of the layers. The source is represented as a spatio-temporal function which describes the generation, propagation, and extinction of the intra-cellular action potential at the end-plate, along the fiber, and at the tendons, respectively. The layers are anisotropic. The volume conductor effect is described as a two dimensional spatial filtering. Electrodes of any shape or dimension are simulated, forming structures which are described as spatial filters. The analytical derivation which leads to the signal in the temporal domain is performed in the spatial and temporal frequency domains. Numerical issues related to the frequency-based approach are discussed. The descriptions of the volume conductor and of the source are applied to the cases of signal generation from a limb and a sphincter muscle. Representative simulations of both cases are provided. The resultant model is based on analytical derivations and constitutes a step forward in surface EMG signal modeling, including features not described in any other analytical approach
A Finite Element Model for Describing the Effect of Muscle Shortening on Surface EMG
No full textUdgivelsesdato: AP
Authors's response to: Football matches and acute cardiac events: Potential effects of a complex psychosocial phenomenon on cardiovascular health
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