Incomplete Muscle Activation After Training With Electromyostimulation

1998 ◽  
Vol 23 (3) ◽  
pp. 261-270 ◽  
Author(s):  
Tibor Hortobágyi ◽  
Jean Lambert ◽  
Kevin Scott
Keyword(s):  
Key Words ◽  
Muscle Activation ◽  
Motor Units ◽  
Eccentric Contraction ◽  
Key Words Exercise ◽  
Eccentric Contractions ◽  
Control Group ◽  
Force Ratio ◽  
Evoked Force ◽  
Large Motor

Training with voluntary or electromyostimulation (EMS)-evoked eccentric contractions should produce complete muscle activation, since EMS and eccentric contractions preferentially recruit large motor units. Subjects (22 women ages 18-40) were randomly assigned to a voluntary (VOL; n = 8), EMS (n = 8), or control group. VOL and EMS groups trained the quadriceps at the same, increasing force levels 4 times/week for 6 weeks using voluntary or EMS-evoked eccentric contractions. VOL improved voluntary more than EMS-evoked eccentric strength. EMS improved EMS-evoked strength more than voluntary. EMS training improved EMS-evoked eccentric strength more than VOL training improved voluntary eccentric strength. EMS-evoked to voluntary force ratio increased from 0.57 (±0.11) to 1.20 (±0.35) in EMS and did not change in VOL (all changes p < .05). Six of eight EMS subjects produced greater EMS-evoked force posttraining, suggesting incomplete muscle activation after EMS training. Key words: exercise, eccentric contraction, muscle activation

Effect of endurance training on muscle activation and force sensation

1995 ◽  
Vol 73 (12) ◽  
pp. 1765-1773 ◽  
Author(s):  
E. Cafarelli ◽  
F. Liebesman ◽  
J. Kroon
Keyword(s):  
Endurance Training ◽  
Muscle Activation ◽  
Vastus Lateralis ◽  
Endurance Performance ◽  
Motor Units ◽  
Control Group ◽  
Reduction In Force ◽  
Leg Cycling ◽  
Before And After ◽  
And Control

One of the consequences of endurance training is a reduction in force sensation in trained muscles at any exercise intensity. To study the central and peripheral contributions to this adaptation, we trained six male subjects with single-leg cycling at 60% [Formula: see text] peak (30 min/day × 3 days/week × 8 weeks); six others were matched controls. Measurements were made during separate 20-min, single-leg rides at 70% pre-training [Formula: see text] peak, with trained (TR), untrained (UT), and control (CT) legs, before and after training. No pre–post differences were observed in the control group. [Formula: see text] peak increased 18% (p < 0.05) in the TR leg and 6% (p < 0.05) in the UT leg of the trained subjects. Force sensation was significantly less in both the TR (70%; p < 0.05) and UT (50%; p < 0.05) legs during 20 min of single-leg cycling after training. Vastus lateralis EMG, plasma lactate, and heart rate were all significantly (p < 0.05) lower when cycling with either the TR or UT leg, which were both lower than when cycling with the CT leg, at the end of each 20-min ride. These data reflect an intramuscular environment that is better adapted to endurance performance by virtue of both central and peripheral mechanisms. Thus, there is less need to recruit additional motor units to maintain the same power output, and this reduced motor outflow leads to a decline in force sensation.Key words: kinesthesia, proprioception, electromyography, single-leg training, endurance training.

Decompensation placental dysfunction: diagnostics and delivery tactics

2017 ◽  
pp. 66-68
Author(s):  
V.I. Boyko ◽  
◽  
S.A. Tkachenko ◽  
Keyword(s):  
Pregnant Women ◽  
Key Words ◽  
Retrospective Analysis ◽  
Control Group ◽  
Present Stage ◽  
Placental Dysfunction ◽  
Perinatal Pathology ◽  
Delivery Times ◽  
Case Rate ◽  
Major Factors

The objective: depression of frequency of perinatal pathology at women with decompensation form of placental dysfunction by improvement of the main diagnostic and treatment-and-prophylactic actions. Patients and methods. 154 pregnant women in gestation term from 22 to 40 weeks were surveyed. Depending on features of course of pregnancy and families of all surveyed it was divided into 4 groups. The group of the retrospective analysis was made by 45 pregnant women with decompensation placental dysfuction, the group of prospective research included 109 pregnant women of whom the main group was made by 38 women with decompensation form of placental dysfunction, the group of comparison included 47 pregnant women with the compensated form of placental dysfunction. The control group was made by 24 pregnant women with the uncomplicated course of pregnancy and labors. The complex of the conducted researches included clinical, ehografical, dopplerometrical, laboratory, morphological and statistical methods. Results. Use of advanced algorithm of diagnostic and treatment-and-prophylactic actions allows to increase efficiency of diagnostics of decompensation form of placental dysfunction for 33.3%, and rational tactics of a delivery leads to depression of perinatal pathology for 22.7%. Conclusion. Decompensation placental dysfuction is one of the main reasons for perinatal mortality and a case rate at the present stage. Use of the algorithm of diagnostic and treatment-and-prophylactic actions improved by us allows major factors of risk of this complication and the indication for change of tactics and delivery times. Key words: decompensation placental dysfunction, diagnostics, delivery tactics.

scholarly journals Modulation of torque evoked by wide-pulse, high-frequency neuromuscular electrical stimulation and the potential implications for rehabilitation and training

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Chris Donnelly ◽  
Jonathan Stegmüller ◽  
Anthony J. Blazevich ◽  
Fabienne Crettaz von Roten ◽  
Bengt Kayser ◽  
...  
Keyword(s):  
Electrical Stimulation ◽  
High Frequency ◽  
Neuromuscular Electrical Stimulation ◽  
Motor Units ◽  
Progressive Increase ◽  
Great Promise ◽  
Measured Parameter ◽  
Time Integral ◽  
Spinal Circuitry ◽  
Evoked Force

AbstractThe effectiveness of neuromuscular electrical stimulation (NMES) for rehabilitation is proportional to the evoked torque. The progressive increase in torque (extra torque) that may develop in response to low intensity wide-pulse high-frequency (WPHF) NMES holds great promise for rehabilitation as it overcomes the main limitation of NMES, namely discomfort. WPHF NMES extra torque is thought to result from reflexively recruited motor units at the spinal level. However, whether WPHF NMES evoked force can be modulated is unknown. Therefore, we examined the effect of two interventions known to change the state of spinal circuitry in opposite ways on evoked torque and motor unit recruitment by WPHF NMES. The interventions were high-frequency transcutaneous electrical nerve stimulation (TENS) and anodal transcutaneous spinal direct current stimulation (tsDCS). We show that TENS performed before a bout of WPHF NMES results in lower evoked torque (median change in torque time-integral: − 56%) indicating that WPHF NMES-evoked torque might be modulated. In contrast, the anodal tsDCS protocol used had no effect on any measured parameter. Our results demonstrate that WPHF NMES extra torque can be modulated and although the TENS intervention blunted extra torque production, the finding that central contribution to WPHF NMES-evoked torques can be modulated opens new avenues for designing interventions to enhance WPHF NMES.

scholarly journals Effects of trunk extensor eccentric exercise on lipid profile and glycaemic response

2020 ◽  
Vol 6 (1) ◽  
pp. e000861
Author(s):  
Ho-Seong Lee ◽  
Takayuki Akimoto ◽  
Ah-Ram Kim
Keyword(s):  
Lipid Profile ◽  
Muscle Soreness ◽  
Blood Lipid ◽  
Eccentric Contraction ◽  
Trunk Muscles ◽  
Eccentric Contractions ◽  
Glycaemic Response ◽  
Concentric Contractions ◽  
Positive Effects ◽  
Trunk Extensor

ObjectivesA number of previous studies reported physiological responses and adaptations after eccentric muscle contraction of limb muscles. In contrast, no study has determined physiological response after eccentric contraction of trunk muscles. The purpose of the present study was to compare the functional and metabolic changes after eccentric or concentric exercises of trunk extensor muscles.MethodsIn this randomised, crossover study, 10 men performed a single bout of 50 maximal voluntary concentric and eccentric contractions of the trunk extensor with an interval of 2 weeks between bouts. The activities of the paraspinal muscles were recorded during concentric and eccentric contractions. Muscle soreness, muscle function, blood lipid profiles and glycaemic responses were measured before, immediately after and at 24, 48, 72 and 96 hours after each bout.ResultsThe lumbar multifidus and iliocostalis lumborum activities during eccentric contractions were significantly higher than those during concentric contractions (p<0.05). The maximal strength and muscle endurance of the trunk extensor were not decreased even after the eccentric contractions. Compared with concentric contractions, muscle soreness was significantly increased at 24, 48, 72 and 96 hours after eccentric contractions (p<0.05). The TG, TC and LDL-C were significantly lower at 48, 72 and 96 hours after eccentric contractions (p<0.05), while blood glucose levels and HOMA-IR were significantly greater at 48 and 72 hours after eccentric contractions (p<0.05).ConclusionThis study indicated that eccentric contractions of the trunk extensor had positive effects on the lipid profile and the glycaemic response.

scholarly journals The Effects of Abdominal Hypopressive Training on Postural Control and Deep Trunk Muscle Activation: A Randomized Controlled Trial

2021 ◽  
Vol 18 (5) ◽  
pp. 2741
Author(s):  
María del Mar Moreno-Muñoz ◽  
Fidel Hita-Contreras ◽  
María Dolores Estudillo-Martínez ◽  
Agustín Aibar-Almazán ◽  
Yolanda Castellote-Caballero ◽  
...  
Keyword(s):  
Postural Control ◽  
Muscle Activation ◽  
Center Of Pressure ◽  
Controlled Trial ◽  
Trunk Muscle ◽  
Posture Control ◽  
Trunk Muscles ◽  
Control Group ◽  
Female Population ◽  
Imaging Results

Background: Abdominal Hypopressive Training (AHT) provides postural improvement, and enhances deep trunk muscle activation. However, until recently, there was a lack of scientific literature supporting these statements. The major purpose of this study was to investigate the effect of AHT on posture control and deep trunk muscle function. Methods: 125 female participants aged 18–60 were randomly allocated to the Experimental Group (EG), consisting of two sessions of 30 min per week for 8 weeks of AHT, or the Control Group (CG), who did not receive any treatment. Postural control was measured with a stabilometric platform to assess the static balance and the activation of deep trunk muscles (specifically the Transverse Abdominal muscle (TrA)), which was measured by real-time ultrasound imaging. Results: The groups were homogeneous at baseline. Statistical differences were identified between both groups after intervention in the Surface of the Center of Pressure (CoP) Open-Eyes (S-OE) (p = 0.001, Cohen’s d = 0.60) and the Velocity of CoP under both conditions; Open-Eyes (V-OE) (p = 0.001, Cohen´s d = 0.63) and Close-Eyes (V-CE) (p = 0.016, Cohen´s d = 0.016), with the EG achieving substantial improvements. Likewise, there were statistically significant differences between measurements over time for the EG on S-OE (p < 0.001, Cohen´s d = 0.99); V-OE (p = 0.038, Cohen´s d = 0.27); V-CE (p = 0.006, Cohen´s d = 0.39), anteroposterior movements of CoP with Open-Eyes (RMSY-OE) (p = 0.038, Cohen´s d = 0.60) and activity of TrA under contraction conditions (p < 0.001, Cohen´s d = 0.53). Conclusions: The application of eight weeks of AHT leads to positive outcomes in posture control, as well as an improvement in the deep trunk muscle contraction in the female population.

scholarly journals Investigation of different stimulation patterns with doublet pulses to reduce muscle fatigue

2019 ◽  
Vol 6 ◽  
pp. 205566831982580 ◽  
Author(s):  
Ruslinda Ruslee ◽  
Jennifer Miller ◽  
Henrik Gollee
Keyword(s):  
Electrical Stimulation ◽  
Muscle Fatigue ◽  
Functional Electrical Stimulation ◽  
Muscle Activation ◽  
Motor Units ◽  
Pulse Interval ◽  
Time Interval ◽  
Fatigue Index ◽  
Significant Difference ◽  
Cord Injury

Introduction: Functional electrical stimulation is a common technique used in the rehabilitation of individuals with a spinal cord injury to produce functional movement of paralysed muscles. However, it is often associated with rapid muscle fatigue which limits its applications. Methods: The objective of this study is to investigate the effects on the onset of fatigue of different multi-electrode patterns of stimulation via multiple pairs of electrodes using doublet pulses: Synchronous stimulation is compared to asynchronous stimulation patterns which are activated sequentially (AsynS) or randomly (AsynR), mimicking voluntary muscle activation by targeting different motor units. We investigated these three different approaches by applying stimulation to the gastrocnemius muscle repeatedly for 10 min (300 ms stimulation followed by 700 ms of no-stimulation) with 40 Hz effective frequency for all protocols and doublet pulses with an inter-pulse-interval of 6 ms. Eleven able-bodied volunteers (28 ± 3 years old) participated in this study. Ultrasound videos were recorded during stimulation to allow evaluation of changes in muscle morphology. The main fatigue indicators we focused on were the normalised fatigue index, fatigue time interval and pre-post twitch–tetanus ratio. Results: The results demonstrate that asynchronous stimulation with doublet pulses gives a higher normalised fatigue index (0.80 ± 0.08 and 0.87 ± 0.08) for AsynS and AsynR, respectively, than synchronous stimulation (0.62 ± 0.06). Furthermore, a longer fatigue time interval for AsynS (302.2 ± 230.9 s) and AsynR (384.4 ± 279.0 s) compared to synchronous stimulation (68.0 ± 30.5 s) indicates that fatigue occurs later during asynchronous stimulation; however, this was only found to be statistically significant for one of two methods used to calculate the group mean. Although no significant difference was found in pre-post twitch–tetanus ratio, there was a trend towards these effects. Conclusion: In this study, we proposed an asynchronous stimulation pattern for the application of functional electrical stimulation and investigated its suitability for reducing muscle fatigue compared to previous methods. The results show that asynchronous multi-electrode stimulation patterns with doublet pulses may improve fatigue resistance in functional electrical stimulation applications in some conditions.

Results of an experimental study of hydrogel drainage containing ranibizumab in antiglaucoma operations

2021 ◽  
pp. 63-67
Author(s):  
I.I. Khusnitdinov ◽  
Keyword(s):  
Experimental Study ◽  
Hyaluronic Acid ◽  
Key Words ◽  
Experimental Research ◽  
Experimental Studies ◽  
Glaucoma Surgery ◽  
Control Group ◽  
Morphological Studies

Purpose. Еxperimental substantiation of the effectiveness of biocompatible biodegradable hydrogels based on hyaluronic acid and chitosan succinate as a carrier of ranibizumab in antiglaucoma operations. Material and methods. Hydrogel drainage (HD) was obtained immediately before surgery. A solution of ranibizumab (0.23 ml) was mixed with a solution of hyaluronic acid dialdehyde (0.5 ml), then a solution of chitosan succinate (0.5 ml) was added. Experimental studies were performed in 12 (12 eyes) healthy rabbits. The first group consisted of 6 eyes – 0.187 ml of ranibizumab per 1 ml of gel. In the control group, HD was used intraoperatively without the addition of ranibizumab (6 eyes). Morphological studies were performed on 7th, 21st, and 42nd days. Results. In experimental studies in vitro and in vivo, it was proved that ranibizumab, administered as a part of 0.1 ml of hydrogel drainage in the antiglaucoma surgery area is released within 3 weeks and suppresses vascularization, scarring of the operating area, and preserves the intrascleral cavity. The optimal concentration of ranibizumab was selected-0.02 ml in 0.1 ml of gel. Conclusion. The safety and effectiveness of the use of hydrogel drainage with ranibizumab based on hyaluronic acid dialdehyde and chitosan succinate in anti-glaucoma operations has been proven. Key words: experimental research, hydrogel drainage, ranibizumab, glaucoma surgery.

Optimisation of the diagnostic and therapeutic algorithm for dealing with psychogenic amenorrhea from the standpoint of the interdisciplinary approach

2018 ◽  
pp. 26-32
Author(s):  
Z.M. Vedeneieva ◽  
◽  
I.V. Prima ◽  
V.M. Goncharenko ◽  
Yu.V. Kravchenkо ◽  
...  
Keyword(s):  
Key Words ◽  
Interdisciplinary Approach ◽  
Main Group ◽  
Stress Disorders ◽  
Control Group ◽  
Menstrual Function ◽  
Therapeutic Algorithm ◽  
Complex Therapy ◽  
Reactive Anxiety ◽  
Post Stress

The objective: was to optimize the treatment of patients with post-stress disorders of menstrual function by conducting pathogenetic complex therapy from the perspective of an interdisciplinary approach. Materials and methods. 54 women aged 19-37 years with psychogenic amenorrhea (PA) – the main group – were examined. The control group included 25 practically healthy patients aged 18 to 35 years. Results. The variants of hormonal disorders in this pathology are determined, the analysis of the results of electroencephalography and the study of individual and reactive anxiety in patients with PA are performed. The presence of three pathogenetic variants of hormonal disorders was established, which became the criterion of the proposed differentiated pathogenetic treatment. Conclusion. Features of the pathogenesis of psychogenic amenorrhea, the complexity of neuroendocrine and hormonal disorders indicate the need for an interdisciplinary approach in the examination, treatment and rehabilitation of this category of patients with the involvement of related specialists – a neurologist and psychotherapist. Key words: amenorrhea, stress, Noofen®, Cyclodinone, electroencephalography, reactive anxiety, individual anxiety, hyperprolactinaemia, hypercortisolemia.

scholarly journals Sequential muscle activation in the hemiparetic arm

2004 ◽  
Vol 60 (2) ◽  
Author(s):  
C. Mucha
Keyword(s):  
Patient Group ◽  
Healthy Subjects ◽  
Muscle Activation ◽  
Deltoid Muscle ◽  
Middle Part ◽  
Control Group ◽  
Biceps Muscle ◽  
Significant Prolongation ◽  
Healthy Control ◽  
Simultaneous Activation

This study investigated the chronological activation sequence of multiple joint movements of the hemiparetic arm in patients with central hemiparesis compared to healthy test subjects.Twelve patients with central hemiparesis and eight healthy control subjects were studied. First, in rapid abduction movement of the upper limb, the electromyographic activities of the middle part of the deltoid muscle, the brachial biceps muscle and the extensor muscles of the fingers, were registered. Second, in rapid flexion of the arm, the electromyographic activities of the ventral part of the deltoid muscle, the brachial biceps muscle and the superficial flexor muscles of the fingers, were measured. From the EMG data registered, activation duration, activation latency and the innervation sequence were determined and compared between the patient group and the control group. In the patient group, a significant prolongation of the activation duration was shown only in abduction. However, the activation latency was significantly prolonged in both movements compared to healthy test subjects. In the innervation sequences, a simultaneous activation was most frequently shown in healthy subjects. In healthy subjects, the deltoid muscle also usually functioned as leading muscle, whereas there was sometimes a shift distally to the brachial biceps muscle in the hemiparetic patients. The speed of rapid multiple joint movements in hemiparetic extremities seems to be unaffected in certain movements (anteversion), in others (abduction) it seems to be significantly reduced. This, as well as the fact that the activation latency is significantly longer in the hemiparetic limbs should be taken into consideration when choosing rehabilitation exercises.

Effects of activation pattern on nonisometric human skeletal muscle performance

2007 ◽  
Vol 102 (5) ◽  
pp. 1985-1991 ◽  
Author(s):  
Ryan D. Maladen ◽  
Ramu Perumal ◽  
Anthony S. Wexler ◽  
Stuart A. Binder-Macleod
Keyword(s):  
Skeletal Muscle ◽  
Instantaneous Frequency ◽  
Muscle Activation ◽  
Motor Units ◽  
Muscle Performance ◽  
Variable Frequency ◽  
Constant Frequency ◽  
Muscle Activation Patterns ◽  
Activation Rate ◽  
Discharge Patterns

During volitional muscle activation, motor units often fire with varying discharge patterns that include brief, high-frequency bursts of activity. These variations in the activation rate allow the central nervous system to precisely control the forces produced by the muscle. The present study explores how varying the instantaneous frequency of stimulation pulses within a train affects nonisometric muscle performance. The peak excursion produced in response to each stimulation train was considered as the primary measure of muscle performance. The results showed that at each frequency tested between 10 and 50 Hz, variable-frequency trains that took advantage of the catchlike property of skeletal muscle produced greater excursions than constant-frequency trains. In addition, variable-frequency trains that could achieve targeted trajectories with fewer pulses than constant-frequency trains were identified. These findings suggest that similar to voluntary muscle activation patterns, varying the instantaneous frequency within a train of pulses can be used to improve muscle performance during functional electrical stimulation.

Sign in / Sign up

Export Citation Format

Share Document