Search results for " contraction"
showing 10 items of 953 documents
Central and peripheral fatigue of the knee extensor muscles induced by electromyostimulation.
2005
The main purpose of this study was to characterise neuromuscular fatigue induced by 30 contractions of the knee extensor muscles evoked by electromyostimulation (EMS). Twelve healthy subjects were tested before and after a typical EMS session (frequency: 75 Hz, on-off ratio: 6.25 s on-20 s off) used for quadriceps femoris muscle strengthening. Surface electromyographic (EMG) activity and torque obtained during maximal voluntary and electrically evoked contractions were analysed to distinguish peripheral from central fatigue. Maximal voluntary torque of the knee extensor muscles decreased approximately 20 % (p < 0.001) following EMS. In the same way, peak torque associated to single (p < 0.0…
Muscle loading and activation of the shoulder joint during humeral external rotation by pulley and variable resistance.
2010
The aim of the study was to evaluate differences in the loading of glenohumeral joint muscles between a cable pulley machine (CP) and variable resistance machine (VR) during axial humeral external rotation.Eleven healthy male subjects took part in the study. Intramuscular electromyography from five muscles of the shoulder (medial deltoid, supraspinatus, infraspinatus and upper part of the trapezius), torque and power output was measured at different rotation angles and with different loads (10%, 50% and 100% of 1RM). Also the compressive and shear force in the glenohumeral joint was analyzed at the horizontal level at angles of rotation. External rotation was performed with a self-selected …
Safety and feasibility of a neuromuscular electrical stimulation chronaxie-based protocol in critical ill patients: A prospective observational study
2017
International audience; Purpose: The aim of this study was to evaluate the safety and feasibility of a neuromuscular electrical stimulation (NMES) protocol based on neuromuscular excitability and applied in numerous muscle groups of critical ill patients.Materials and methods: We performed a prospective observational study using an NMES applied daily and bilaterally into 5 muscle groups in lower limbs for 3 consecutive days. The characteristics of NMES were 90 contractions per muscle, pulse width equal to chronaxie, and a pulse frequency of 100 Hz. We assessed safety with central venous oxygen saturation, serum lactate, and creatine phosphokinase measurements. To evaluate feasibility, we re…
Serum hormones during prolonged training of neuromuscular performance.
1985
The effects of a 24-weeks' progressive training of neuromuscular performance capacity on maximal strength and on hormone balance were investigated periodically in 21 male subjects during the course of the training and during a subsequent detraining period of 12 weeks. Great increases in maximal strength were noted during the first 20 weeks, followed by a plateau phase during the last 4 weeks of training. Testosterone/cortisol ratio increased during training. During the last 4 weeks of training changes in maximal strength correlated with the changes in testosterone/cortisol (P less than 0.01) and testosterone/SHBG (P less than 0.05) ratios. During detraining, correlative decreases were found…
Innervation zone shift at different levels of isometric contraction in the biceps brachii muscle
2007
Experiments were carried out to examine whether innervation zone (IZ) location remains stable at different levels of isometric contraction in the biceps brachii muscle (BB), and to determine how the proximity of the IZ affects common surface electromyography (sEMG) parameters. Twelve subjects performed maximal (MVC) and submaximal voluntary isometric contractions at 10%, 20%, 30%, 40%, 50% and 75% of MVC. sEMG signals were recorded with a 13 rows x 5 columns grid of electrodes from the short head of BB. The IZ shifted in the proximal direction by up to 2.4 cm, depending upon the subject and electrode column. The mean shift of all the columns was 0.6+/-0.4 cm (10% vs. 100% MVC, P0.001). This…
Reproducibility of isometric strength: measurement of neck muscles
1999
Abstract Objective. To evaluate the repeatability of an advanced method of measuring the strength of functionally different groups of neck muscles using an isometric apparatus. Design. A repeated measures design was used within and between sessions. Background. Chronic neck pain has been associated with poor isometric neck strength. In rehabilitation, strength measurements may thus help to evaluate the basic condition and show whether or not treatments and exercises have been beneficial for improving strength. Previous tests have concentrated on testing strength while trying to bend forwards and backwards, but no biomechanics device, able to test rotator muscles, has been presented. Method.…
Surface electrical stimulation of the quadriceps femoris in patients affected by haemophilia A.
2006
Eighteen sessions of surface electrical stimulation was applied to the quadriceps femoris of the left leg of ten male subjects affected by severe haemophilia A, while ten healthy subjects constituted the control group. The isometric strength, the electromyographic activity and the diameter of the rectus femoris were measured in both legs before and after a six-week treatment period. After the treatment, the people affected by haemophilia showed a gain in strength by 13.8% in the stimulated leg and by 17.1% in the non-stimulated one. No changes were detected in the electromyographic activity. On the contrary, the diameter of the rectus femoris of the stimulated leg increased in 24.34%, while…
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…
Effects of Kinesio® Tape in low back muscle fatigue: randomized, controlled, doubled-blinded clinical trial on healthy subjects.
2013
BACKGROUND: Muscle fatigue of the trunk extensor musculature plays a considerable role in chronic low back pain (LBP). The underlying physiology of fatigue is complex and not fully understood. The Kinesio Taping (KT) supports damaged structures while allowing mobility and at the same time may influence some of the mechanisms associated with muscle fatigue such as blood flow and proprioception. OBJECTIVE: The aim of this study is to determine the influence of KT on the resistance to fatigue of the lumbar extensor musculature in a sample of young healthy subjects. METHODS: A randomized, controlled, doubled-blinded clinical trial was conducted. Ninety nine healthy subjects were randomized in t…
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…