Search results for "electromyography"
showing 10 items of 672 documents
Functional properties of motor units in motor neuron diseases and neuropathies.
1997
The relationship between the size of single motor unit (MU) action potentials and their twitch properties was estimated in patients with spinal muscular atrophy (SMA, n = 5) and amyotrophic lateral sclerosis (ALS, n = 10), as well as in patients with peripheral nerve lesions (PNL, n = 9). The data obtained from these groups were compared to normal controls (n = 8). In controls, the single MU twitch force was highly correlated to the corresponding EMG potential size in terms of macro EMG area. An enlargement of MUs, due to collateral sprouting and reflected by increased potential size and twitch force, was found in regenerating PNL and in slowly progressing SMA. Both parameters were highly c…
Is the V˙o 2 slow component dependent on progressive recruitment of fast-twitch fibers in trained runners?
2001
The goal of this study was to use spectral analysis of EMG data to test the hypothesis that the O2 uptake (V˙o 2) slow component is due to a recruitment of fast fibers. Thirteen runners carried out a treadmill test with a constant speed, corresponding to 95% of the velocity associated with maximal V˙o 2. TheV˙o 2 response was fit with the classical model including three exponential functions. Electrical activity of six lower limb muscles (vastus lateralis, soleus, and gastrocnemius of both sides) was measured using electromyogram surface electrodes. Mean power frequency (MPF) was used to study the kinetics of the electromyogram discharge frequency. Three main results were observed: 1) a co…
Concurrent validation of the OMNI-resistance exercise scale of perceived exertion with Thera-band resistance bands.
2012
The concurrent validity of the OMNI-Resistance Exercise Scale (OMNI-RES) of perceived exertion for use with elastic bands was studied during isotonic resistance exercises. Twenty healthy, physically active subjects completed both familiarization and testing sessions. The criterion variables were myoelectric activity, recorded by electromyography, and heart rate, recorded by a heart rate monitor. The subjects performed 2 separate sets of 15 repetitions in each of the 2 testing sessions and for each of the exercises applied (i.e., frontal and lateral raises). One set was carried out with the separation between the hands gripping the elastic band allowing that 15 repetition maximum to be perfo…
Central Versus Peripheral Adaptations Following Eccentric Resistance Training
2002
Aim of the present investigation was to study the effects of an eccentric training on the neuromuscular properties of the plantar-flexor muscles. The experiment was carried out on 14 males divided into two groups (eccentric and control). Eccentric training consisted of six sets of six eccentric contractions at 120 % of one maximal concentric repetition and it was performed four times a week during four weeks. Before and after the 4-wk period, the plantar-flexor torque and the associated electromyographic activity were recorded during voluntary contractions (isometric, concentric and eccentric) and electrically induced contractions (twitch and tetanus), in order to distinguish central from p…
Neuromuscular Adaptations to Different Modes of Combined Strength and Endurance Training
2014
The present study investigated neuromuscular adaptations between same-session combined strength and endurance training with 2 loading orders and different day combined training over 24 weeks. 56 subjects were divided into different day (DD) combined strength and endurance training (4-6 d·wk(-1)) and same-session combined training: endurance preceding strength (E+S) or vice versa (S+E) (2-3 d·wk(-1)). Dynamic and isometric strength, EMG, voluntary activation, muscle cross-sectional area and endurance performance were measured. All groups increased dynamic one-repetition maximum (p<0.001; DD 13±7%, E+S 12±9% and S+E 17±12%) and isometric force (p<0.05-0.01), muscle cross-sectional area (p<0.0…
Biomechanical factors affecting running economy.
2001
KYROLAINEN, H., A. BELLI, and P. V. KOMI. Biomechanical factors affecting running economy. Med. Sci. Sports Exerc., Vol. 33, No. 8, 2001, pp. 1330 -1337. Purpose: The present study was designed to investigate kinematics, kinetics, and muscle activity for explaining running economy at different running speeds. Methods: A total of 17 young endurance runners ran at 12-13 different running speeds. Respiratory gases were collected. Kinematic records were obtained by a high-speed video camera, and 3-D ground reaction forces (GRF) were measured simultaneously with telemetric EMG recordings of the selected leg muscles. In the analysis, joint moments and power were calculated by inverse dynamic meth…
Effect of body composition on the neuromuscular function of Finnish conscripts during an 8-week basic training period.
2008
The dropout rate in the Finnish military service has increased during the past two decades. At the same time, the physical fitness level of young Finnish males has decreased, possibly leading to overtraining in new conscripts. The purpose of the present study was to examine whether body composition would influence neuromuscular function during the 8-week basic training (BT) period. Eighteen healthy male subjects (19 +/- 1 years) were divided into three different groups according to their body fat %. Group 1 (10%), group 2 (10-13%) and group 3 (13%). The soleus H-reflex response was measured in the standing position. In the seated position (knee 160 degrees and hip 110 degrees), the V-wave r…
Muscle strength and muscle characteristics in monozygous and dizygous twins.
1979
Muscle strength and electrical activity were investigated on 31 pairs of young male and female monozygous (MZ) and dizygous (DZ) twins. The measurements included leg forces, force-time, running velocity, muscular power, maximal integrated electromyographic activity (IEMG) and chronaximetry of the quadriceps muscle group. In each parameter the intrapair variance was computed and the differences were tested between the MZ and DZ twins. The variance ratio (MZ vs. DZ) was statistically significant only for muscular power confirming an earlier finding which has demonstrated a genetic component for the variable. In addition to the various performance variables several key enzymes involved in ATP …
Evidence of unilateral isolated utricular hypofunction
2010
The findings demonstrate that an enduring unilateral utricular dysfunction, possibly together with canal hypofunction, can occur after labyrinthine disease or injury. They also suggest that unilateral, isolated utricular dysfunction - or utricle paresis - can occur, representing a novel entity in the differential diagnosis of peripheral vestibular function. The occurrence of subjective visual vertical (SVV) asymmetry in the presence of symmetric vestibular evoked myogenic potentials (VEMPs) also confirms that the information from the utricles, rather than the saccules, dominates SVV estimation.To determine the incidence of unilateral utricular hypofunction.The retrospective clinical study d…
Age-related decreases in motor unit discharge rate and force control during isometric plantar flexion.
2012
Aging is related to multiple changes in muscle physiology and function. Previous findings concerning the effects of aging on motor unit discharge rate (DR) and fluctuations in DR and force are somewhat contradictory. Eight YOUNG and nine OLD physically active males performed isometric ramp (RECR) and isotonic (ISO) plantar flexions at 10 and 20% of surface EMG at MVC. Motor unit (MU) action potentials were recorded with intramuscular fine-wire electrodes and decomposed with custom build software "Daisy". DR was lower in OLD in RECR-10% (17.9%, p0.001), RECR-20% (15.8%, p0.05), ISO-10% (17.7%, p0.01) and ISO-20% (14%, n.s.). In YOUNG force fluctuations were smaller at ISO-10% (72.1%, p0.001)…