1,720,985 research outputs found
Transcutaneous neuromuscular electrical stimulation: influence of electrode positioning and stimulus amplitude settings on muscle response.
No full textThe aim of the study was to investigate the influence of two different transcutaneous neuromuscular electrical stimulation procedures on evoked muscle torque and local tissue oxygenation. In the first one (MP mode), the cathode was facing the muscle main motor point and stimulus amplitude was set to the level eliciting the maximal myoelectrical activation according to the amplitude of the evoked electromyogram (EMG); in the second one (RC mode), the electrodes were positioned following common reference charts for electrode placement while stimulus amplitude was set according to subject tolerance. Tibialis Anterior (TA) and Vastus Lateralis (VL) muscles of 10 subjects (28.4 ± 8.2 years) were tested in specific dynamometers to measure the evoked isometric torque. The EMG and near-infrared spectroscopy probes were placed on muscle belly to detect the electrical activity and local metabolic modifications of the stimulated muscle, respectively. The stimulation protocol consisted of a gradually increasing frequency ramp from 2 to 50 Hz in 7.5 s. Compared to RC mode, in MP mode the contractile parameters (peak twitch, tetanic torque, area under the torque build-up) and the metabolic solicitation (oxygen consumption and hyperemia due to metabolites accumulation) resulted significantly higher for both TA and VL muscles. MP mode resulted also to be more comfortable for the subjects. Based on the assumption that proper mechanical and metabolic stimuli are necessary to induce muscle strengthening, our results witness the importance of an optimized, i.e., comfortable and effective, stimulation to promote the aforementioned muscle adaptive modifications
Design Approach of Medical Devices for Regulation Compatibility: A Robotic Rehabilitation Case Study
No full textRegulations and normative framework strongly affect requirements and potential design constraints of devices, especially in critical environments like the medical field, characterized by a complex interaction among design, therapy procedures and user needs. In order to optimize the design process, the awareness of the designer about the compound information net generated by the required documentation becomes therefore fundamental. Depicting a custom mapping of required data and referring documents for the development and commercialization of a medical device as required by the Conformité Européenne (CE) marking process, this paper presents a design approach directly suitable for robotic rehabilitation systems, which aims at easing the regulations compatibility of the designed product. This method is applied to the illustrative case study of the LEPRE (LEg Programmable REhabilitation) robotic system, with particular attention to data collection and analysis for the evaluation of clinical background and demonstration of equivalence required by the device clinical evaluation report, according to MEDical DEVices (MEDDEV) 2.7/1 guidelines. Indications for the modifications required to adapt it to further application fields are also suggested
Muscle echo intensity of abdominal wall in Parkinson’s disease and healthy controls: a cross sectional study
No full textPurpose: The aim of this study was to describe the differences between abdominal wall muscles echo intensity (EI) in PD patients and healthy controls. Methods: Forty-three consecutive PD patients (25 males and 18 females, age 73.7 ± 7.1, and 42 controls without neurological diseases (22 males, 20 females, age 69.8 ± 6.0) participated in this cross-sectional study. The clinical assessment included the following: IPAQ (International Physical Activity Questionnaire), Hoehn Yahr score, plumb line distance from the spinous process of C7, kyphosis apex, and spinous process of L3 and S1. A real-time ultrasound B-scanner (system MyLab40 by Esaote, Genoa, Italy) was used to obtain muscle images of the right and left biceps brachii (BB), external (EO), and internal oblique (IO) and rectus abdomen (RA). Heckmatt scale and measure of EI through ImageJ software were used to assess muscle quality. Results: When considering the Heckmatt score, the RA and BB did not significantly differ between PD and control patients, while there was a significant difference for right (p < 0.01) and left (p = 0.02) IO muscles. There was no difference among EI values of the RA, IO, and BB between PD and control patients. Conclusions: Echo intensity of abdominal wall muscles (rectus abdominis, internal oblique) and biceps brachii did not differ between Parkinsonian patients and healthy subjects. We did not found ultrasound useful in disease evolution assessment or in early diagnosis of postural disorders
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Neuromuscular electrical stimulation modulates motor cortical excitability in healthy subjects and stroke patients
No full textExtra-torque of human tibialis anterior during electrical stimulation with linearly varying frequency and amplitude trains.
No full textThis work aimed to characterise the whole human muscle input/output law during electrical stimulation with triangular varying frequency and amplitude trains through combined analysis of torque, mechanomyogram (MMG) and electromyogram (EMG). The tibialis anterior (TA) of ten subjects (age 23-35years) was investigated during static contraction obtained through neuromuscular electrical stimulation. After potentiation, TA underwent two 15s stimulation patterns: (a) frequency triangle (FT): 2>35>2Hz at Vmax (amplitude providing full motor unit recruitment); (b) amplitude triangle (AT): Vmin>Vmax>Vmin (Vmin providing TA least mechanical response) at 35Hz. 2>35Hz or Vmin>Vmax as well as 35>2Hz or Vmax>Vmin were defined as up-going ramp (UGR) and down-going ramp (DGR), respectively. TA torque, MMG and EMG were detected by a load cell, an optical laser distance sensor and a probe with two silver bar electrodes, respectively. For both FT and AT, only the two mechanical signals resulted always larger in DGR than in UGR, during AT extra-torque and extra-MMG were present even in the first 1/3 of the amplitude range where EMG data presented no significant differences between DGR and UGR. Our data suggest that extra-torque and extra-displacement are evident for both FT and AT, being mainly attributed to an intrinsic muscle property
Normalized maximal rate of torque development during voluntary and stimulated static contraction in human tibialis anterior: Influence of age
No full textThe risk of falling in older adults has been related, among other factors, to the reduction of the rate of torque development (RTD) with age. It is well known that both structural/peripheral and neural factors can influence the RTD. The purpose of this study was to compare the normalized RTD in young and older participants obtained during a) rapid voluntary tension production and b) neuromuscular electrical stimulation. The tibialis anterior of 19 young subjects (10 males and 9 females; age 21–33 years old) and 19 older participants (10 males and 9 females; age 65–80 years old) was studied. The subjects performed a series of maximal isometric explosive dorsiflexions and underwent trains of supra-maximal electrical stimulations (35 Hz) on the tibialis anterior motor point. Muscle shortening was indirectly measured using a laser (surface mechanomyogram, MMG). Both torque and MMG were normalized to their maximum value. Using a 20 ms sliding window on the normalized torque signal, the normalized maximum RTD was calculated for both voluntary and stimulated contractions. Active stiffness of the muscle- tendon unit was calculated as the area of the normalized torque with respect to the normalized MMG. Normalized maximum RTD was found significantly lower in older adults during voluntary activity (young: 751.9 ± 216.3%/s and old: 513.9 ± 173.9%/s; P < .001), and higher during stimulated contractions (young: 753.1 ± 225.9%/s and old: 890.1 ± 221.3%/s; P = .009). Interestingly, active stiffness was also higher in older adults (young: 3524.6 ± 984.6‰ and old 4144.6 ± 816.6‰; P = .041) and significantly correlated to the normalized maximum RTD during stimulated contractions. This dichotomy suggests that modifications in the structural/peripheral muscle properties are not sufficient to counteract the age-related decrease in neural drive to the muscle during voluntary isometric contractions in aged participants
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