Reflex Inhibition of Normal Cramp Following Electrical Stimulation of the Muscle Tendon

2007 ◽  
Vol 98 (3) ◽  
pp. 1102-1107 ◽  
Author(s):  
Serajul I. Khan ◽  
John A. Burne
Keyword(s):  
Electrical Stimulation ◽  
Maximum Voluntary Contraction ◽  
Voluntary Contraction ◽  
Muscle Cramp ◽  
Emg Activity ◽  
Reflex Inhibition ◽  
Experimental Conditions ◽  
Inhibitory Feedback ◽  
Two Phases ◽  
Stimulation Of

Muscle cramp was induced in one head of the gastrocnemius muscle (GA) in eight of thirteen subjects using maximum voluntary contraction when the muscle was in the shortened position. Cramp in GA was painful, involuntary, and localized. Induction of cramp was indicated by the presence of electromyographic (EMG) activity in one head of GA while the other head remained silent. In all cramping subjects, reflex inhibition of cramp electrical activity was observed following Achilles tendon electrical stimulation and they all reported subjective relief of cramp. Thus muscle cramp can be inhibited by stimulation of tendon afferents in the cramped muscle. When the inhibition of cramp-generated EMG and voluntary EMG was compared at similar mean EMG levels, the area and timing of the two phases of inhibition (I1, I2) did not differ significantly. This strongly suggests that the same reflex pathway was the source of the inhibition in both cases. Thus the cramp-generated EMG is also likely to be driven by spinal synaptic input to the motorneurons. We have found that the muscle conditions that appear necessary to facilitate cramp, a near to maximal contraction of the shortened muscle, are also the conditions that render the inhibition generated by tendon afferents ineffective. When the strength of tendon inhibition in cramping subjects was compared with that in subjects that failed to cramp, it was found to be significantly weaker under the same experimental conditions. It is likely that reduced inhibitory feedback from tendon afferents has an important role in generating cramp.

scholarly journals Electrical Stimulation Frequency and Skeletal Muscle Characteristics: Effects on Force and Fatigue

2017 ◽  
Vol 27 (4) ◽  
Author(s):  
Maria Vromans ◽  
Pouran Faghri
Keyword(s):  
Electrical Stimulation ◽  
Vastus Lateralis ◽  
Voluntary Contraction ◽  
Current Intensity ◽  
Muscle Size ◽  
Emg Activity ◽  
Abductor Pollicis Brevis ◽  
Fiber Composition ◽  
Initial Drop ◽  
Initial Force

This investigation aimed to determine the force and muscle surface electromyography (EMG) responses to different frequencies of electrical stimulation (ES) in two groups of muscles with different size and fiber composition (fast- and slow-twitch fiber proportions) during a fatigue-inducing protocol. Progression towards fatigue was evaluated in the abductor pollicis brevis (APB) and vastus lateralis (VL) when activated by ES at three frequencies (10, 35, and 50Hz). Ten healthy adults (mean age: 23.2 ± 3.0 years) were recruited; participants signed an IRB approved consent form prior to participation. Protocols were developed to 1) identify initial ES current intensity required to generate the 25% maximal voluntary contraction (MVC) at each ES frequency and 2) evaluate changes in force and EMG activity during ES-induced contraction at each frequency while progressing towards fatigue. For both muscles, stimulation at 10Hz required higher current intensity of ES to generate the initial force. There was a significant decline in force in response to ES-induced fatigue for all frequencies and for both muscles (p<0.05). However, the EMG response was not consistent between muscles. During the progression towards fatigue, the APB displayed an initial drop in force followed by an increase in EMG activity and the VL displayed a decrease in EMG activity for all frequencies. Overall, it appeared that there were some significant interactions between muscle size and fiber composition during progression towards fatigue for different ES frequencies. It could be postulated that muscle characteristics (size and fiber composition) should be considered when evaluating progression towards fatigue as EMG and force responses are not consistent between muscles.

Activation varies among the knee extensor muscles during a submaximal fatiguing contraction in the seated and supine postures

2003 ◽  
Vol 95 (4) ◽  
pp. 1515-1522 ◽  
Author(s):  
L Rochette ◽  
S. K. Hunter ◽  
N Place ◽  
R Lepers
Keyword(s):  
Vastus Lateralis ◽  
Maximum Voluntary Contraction ◽  
Knee Extensor ◽  
Voluntary Contraction ◽  
Emg Activity ◽  
Task Failure ◽  
Rate Of Increase ◽  
Extensor Muscles ◽  
Seated Posture ◽  
Knee Extensor Muscles

Ten young men sustained an isometric contraction of the knee extensor muscles at 20% of the maximum voluntary contraction (MVC) torque on three separate occasions in a seated posture. Subjects performed an isometric knee extension contraction on a fourth occasion in a supine posture. The time to task failure for the seated posture was similar across sessions (291 ± 84 s; P > 0.05), and the MVC torque was similarly reduced across sessions after the fatiguing contraction (42 ± 12%). The rate of increase in electromyograph (EMG) activity (%MVC) and torque fluctuations during the fatiguing contractions were similar across sessions. However, the rate of increase in EMG differed among the knee extensor muscles: the rectus femoris began at a greater amplitude (31.5 ± 11.0%) compared with the vastus lateralis and vastus medialis muscles (18.8 ± 5.3%), but it ended at a similar value (45.4 ± 3.1%). The time to task failure and increase in EMG activity were similar for the seated and supine tasks; however, the reduction in MVC torque was greater for the seated posture. These findings indicate that the time to task failure for the knee extensor muscles that have a common tendon insertion did not alter over repeat sessions as had been observed for the elbow flexor muscles (Hunter SK and Enoka RM. J Appl Physiol 94: 108-118, 2003).

Avoidance and approach learning motivated by stimulation of identical hypothalamic loci

1959 ◽  
Vol 197 (1) ◽  
pp. 153-157 ◽  
Author(s):  
George W. Brown ◽  
Bertram D. Cohen
Keyword(s):  
Electrical Stimulation ◽  
Lateral Hypothalamus ◽  
Opportunity To Learn ◽  
Hypothalamic Stimulation ◽  
Experimental Conditions ◽  
Approach Response ◽  
Lateral Hypothalamic ◽  
Stimulating Electrodes ◽  
Second Procedure ◽  
Stimulation Of

Cats with stimulating electrodes implanted in the lateral hypothalamus were subjected to two types of experimental procedures. In the first procedure the cats were given an opportunity to learn to avoid hypothalamic stimulation which produces a typical ‘hypothalamic rage’ response. The second procedure allows the same cats to learn to approach an area where the hypothalamic stimulus is administered. In both procedures, electrical stimulation was delivered through identical electrodes, yet each animal learned the appropriate avoidance or approach response, depending upon the experimental conditions. Therefore, lateral hypothalamic stimulation may act as an energizing, drive-arousing, operation to produce both avoidance and approach learning in cats.

scholarly journals Effect of Elbow Flexion Angle on Cortical Voluntary Activation of the Non-Impaired Biceps: A 3 Days Repeated Sessions Study

2020 ◽  
Author(s):  
Thibault Roumengous ◽  
Paul A. Howell ◽  
Carrie L. Peterson
Keyword(s):  
Cortical Neurons ◽  
Maximum Voluntary Contraction ◽  
Motor Evoked Potential ◽  
Elbow Flexion ◽  
Voluntary Contraction ◽  
Voluntary Activation ◽  
Elbow Angle ◽  
Flexion Extension ◽  
Minimal Stimulation ◽  
Stimulation Of

ABSTRACTMeasurement of cortical voluntary activation (VA) with transcranial magnetic stimulation (TMS) is limited by technical challenges. One challenge is the difficulty in preferential stimulation of cortical neurons projecting to the target muscle and minimal stimulation of cortical neurons projecting to antagonists. Thus, the motor evoked potential (MEP) response to TMS in the target muscle compared to its primary antagonist may be an important parameter in the assessment of cortical VA. Modulating isometric elbow angle alters the magnitude of MEPs at rest. The purpose of this study was to evaluate the effect of isometric elbow flexion-extension angle on: 1) the ratio of biceps MEP relative to the triceps MEP amplitude across a range of voluntary efforts, and 2) cortical VA. Ten non-impaired participants completed three sessions wherein VA was determined using TMS at 45°, 90° and 120° of isometric elbow flexion, and peripheral electrical stimulation at 90° of elbow flexion. The biceps/triceps MEP ratio was greater in the more flexed elbow angle (120° flexion) compared to 90° during contractions of 50% and 75% of maximum voluntary contraction. Cortical VA assessed in the more extended elbow angle (45° flexion) was lower relative to 90° elbow flexion; this effect was dependent on the biceps/triceps MEP ratio. Cortical VA was sensitive to small changes in the linearity of the voluntary torque and superimposed twitch relationship, regardless of the elbow angle. Peripheral and cortical VA measures at 90° of elbow flexion were repeatable across three days. In conclusion, although the biceps/triceps MEP ratio was increased at a more flexed elbow angle relative to 90°, there was not a corresponding difference in cortical VA. Thus, increasing the MEP ratio via elbow angle did not affect estimation of cortical VA.

A STUDY OF THE AUTONOMIC MANIFESTATIONS SEEN IN ACUTE ALDRIN AND DIELDRIN POISONING

1955 ◽  
Vol 33 (1) ◽  
pp. 272-282 ◽  
Author(s):  
C. W. Gowdey ◽  
G. W. Stavraky
Keyword(s):  
Electrical Stimulation ◽  
Salivary Gland ◽  
Central Action ◽  
Chorda Tympani ◽  
Rectus Abdominis Muscle ◽  
Experimental Conditions ◽  
Intravenous Injections ◽  
Submaxillary Salivary Gland ◽  
Reduced Rate ◽  
Stimulation Of

The peripheral parasympathomimetic action of aldrin was investigated in vagotomized and adrenalectomized cats under chloralose and urethane anesthesia. Under these experimental conditions aldrin caused slowing of the heart, potentiated the effects of electrical stimulation of the vagus nerve, and augmented the secretory effect of the chorda tympani on the decentralized submaxillary salivary gland. Blood withdrawn five minutes after intravenous injections of aldrin into cats showed a reduced rate of destruction of added acetylcholine when tested on the frog's rectus abdominis muscle. In spite of a marked central action, dieldrin exerted none of these peripheral effects.

scholarly journals External torque as a factor to modify load in abdominal curl-up exercises

2015 ◽  
Vol 7 (1) ◽  
Author(s):  
Alicja Rutkowska-Kucharska ◽  
Agnieszka Szpala
Keyword(s):  
External Force ◽  
Maximum Voluntary Contraction ◽  
Voluntary Contraction ◽  
Emg Activity ◽  
Electromyographic Activity ◽  
Upper Limbs ◽  
External Torque ◽  
Lever Arm ◽  
Emg Signal ◽  
Ca 50

SummaryStudy aim: the aim of our study was to evaluate electromyography (EMG) activity in exercises where the load to the muscles is determined by the external torque. In a part of the exercises, we changed the value of the external force, while in the other we modified the length of the lever arm at which the force was applied.Material and methods: the study was carried out on a group of 12 subjects (21 ± 2 years, 61 ± 4.8 mass, 172 ± 5 cm height). Electromyographic activity of the rectus abdominis (RA) muscle was evaluated by recording the EMG signal. The length of the lever arm of the external force was changed by using four different positions of the upper limbs, whereas the magnitude of the external force was changed through adding the weights of 0.5, 1.0, and 1.5 kg. The data recorded were normalized with respect to EMG activity measured under maximum voluntary contraction (MVC) conditions.Results: it was found that the change of the lever arm at which the force was applied (any change in the position of the upper limbs) causes a change in EMG activity in each part of the RA muscle from ca. 50% to ca. 100% MVC (p < 0.001). Further, the change in the external load changes statistically significantly the EMG activity only in the left upper part of the RA muscle (p < 0.05).Conclusions: activity in the RA muscle that increased for longer lever arms of the external force, offers opportunities for changing the load used during the exercise in a manner that is safe for the vertebral column.

scholarly journals El impacto inicial con antepié incrementa la actividad muscular del gastrocnemios durante la carrera. Un estudio cuantitativo de actividad electromiográfica (The initial impact with forefoot increases the muscular activity of gastrocnemius during running)

Retos ◽  
2020 ◽  
pp. 271-275
Author(s):  
Oscar Valencia ◽  
Iver Cristi ◽  
Dario Ahumada ◽  
Keiny Meza ◽  
Rodrigo Salas ◽  
...  
Keyword(s):  
Lower Limb ◽  
Stance Phase ◽  
Maximum Voluntary Contraction ◽  
Neuromuscular Control ◽  
Voluntary Contraction ◽  
Medial Gastrocnemius ◽  
Emg Activity ◽  
Myoelectric Activity ◽  
Initial Contact ◽  
Limb Injuries

Un importante porcentaje de las lesiones de miembros inferiores ha sido vinculado a la técnica de carrera, en particular, al contacto inicial con retropié (RP) o antepié (AP). Sin embargo, existe limitada evidencia de la actividad electromiográfica (EMG) para ambas condiciones. El objetivo de este estudio fue comparar la amplitud EMG en miembros inferiores al utilizar técnicas de RP vs AP durante la carrera. Trece corredores fueron evaluado a una velocidad de trote autoseleccionada en dos condiciones: contacto inicial con RP y AP. Se registró la actividad mioeléctrica del recto femoral (RF), bíceps femoral (BF), tibial anterior (TA), gastrocnemio medial (GM) y lateral (GL). Se consideró la amplitud promedio de la EMG en 10 ciclos de carrera, normalizados a la contracción voluntaria máxima. Los resultados destacan una mayor activación significativa de los músculos GM y GL en el contacto AP durante la fase de apoyo, balanceo y en todo el ciclo de carrera. Adicionalmente, el TA presentó una mayor activación durante la fase de vuelo y el 100% del ciclo de carrera para la condición RP. No se encontraron otras diferencias significativas. En conclusión, el uso de la técnica AP incrementa la actividad muscular de GM y GL, posiblemente asociado a una mayor absorción del impacto durante la fase de apoyo. Por otro lado, el TA incrementa su actividad con RP, lo que podría implicar un mayor control previo al contacto inicial. La técnica de carrera se presenta como una condición modificable según situaciones de rendimiento o patología.Abstract. Running technique has an impact on lower limb injuries, particularly the initial contact pattern such as rearfoot (RF) or forefoot (FF). However, there is limited evidence of the electromyographic (EMG) activity for both conditions. The aim of this study was to compare the lower limb muscles EMG amplitude between RF and FF techniques during running. Thirteen runners were evaluated at a self-selected running speed under two conditions: initial contact with RF and FF. The myoelectric activity of the rectus femoris (RE), biceps femoris (BF), tibialis anterior (TA), medial gastrocnemius (GM) and lateral (GL) were analysed. The EMG amplitudes of 10 running cycles were averaged and normalized to the maximum voluntary contraction. The results included a significantly higher activation of GM and GL muscles for the FF condition during the stance phase, balance and the entire running cycle. In addition, TA showed higher activation during the swing phase and the 100% running cycle for the RP condition. No other significant differences were found. In conclusion, FF technique increases GM and GL myoelectric activity, possibly associated with a higher impact absorption during the stance phase. On the other hand, TA increases its activity for RF condition which may imply a greater neuromuscular control prior to initial contact. Finally, the running technique is presented as a modifiable condition which can be changed to enhance performance or in pathologic circumstances.

Coordinated Interlimb Compensatory Responses to Electrical Stimulation of Cutaneous Nerves in the Hand and Foot During Walking

2003 ◽  
Vol 90 (5) ◽  
pp. 2850-2861 ◽  
Author(s):  
Carlos Haridas ◽  
E. Paul Zehr
Keyword(s):  
Electrical Stimulation ◽  
Motor Coordination ◽  
The Body ◽  
Emg Activity ◽  
Motor Tasks ◽  
Step Cycle ◽  
Reflex Responses ◽  
Cutaneous Reflex ◽  
Reflex Pathways ◽  
Stimulation Of

It has been shown that stimulation of cutaneous nerves innervating the hand (superficial radial, SR) and foot (superficial peroneal, SP) elicit widespread reflex responses in many muscles across the body. These interlimb reflex responses were suggested to be functionally relevant to assist in motor coordination between the arms and legs during motor tasks such as walking. The experiments described in this paper were conducted to test the hypothesis that interlimb reflexes were phase-dependently modulated and produced functional kinematic changes during locomotion. Subjects walked on a treadmill while electromyographic (EMG) activity was collected continuously from all four limbs, and kinematic recordings were made of angular changes across the ankle, knee, elbow, and shoulder joints. Cutaneous reflexes were evoked by delivering trains of electrical stimulation pseudorandomly to the SP nerve or SR nerves in separate trials. Reflexes were phase-averaged according to the time of occurrence in the step cycle, and phasic amplitudes and latencies were calculated. For both nerves, significant phase-dependent modulation (including reflex reversals) of interlimb cutaneous reflex responses was seen in most muscles studied. Both SR and SP nerve stimulation resulted in significant alteration in ankle joint kinematics. The results suggest coordinated and functionally relevant reflex pathways from the SP and SR nerves onto motoneurons innervating muscles in nonstimulated limbs during walking, thus extending observations from the cat to that of the bipedal human.

Corticoliberin activity of rat neurohypophysis is distinct from vasopressin

1981 ◽  
Vol 240 (6) ◽  
pp. E689-E693 ◽  
Author(s):  
M. Karteszi ◽  
E. Stark ◽  
G. Rappay ◽  
F. A. Laszlo ◽  
G. B. Makara
Keyword(s):  
Electrical Stimulation ◽  
Median Eminence ◽  
Brattleboro Rats ◽  
Neural Lobe ◽  
Experimental Conditions ◽  
Adrenal Axis ◽  
Corticosterone Secretion ◽  
Pituitary Adrenal Axis ◽  
Stimulation Of

Electrical stimulation of the neural lobe of the pituitary resulted in an increase of corticosterone secretion in both normal and Brattleboro rats. Bioassaying the corticoliberin (CRF) activity of stalk-median eminence and neural lobe extracts obtained from normal and Brattleboro rats revealed that the endogenous vasopressin was not a prerequisite of ACTH-releasing potency. Arginine-8-vasopressin failed to potentiate the CRF activity of the different extracts. These data suggest that a nonvasopressin substance(s) with CRF activity can be released from the neurohypophysis of the rat, and it may contribute to activating the pituitary-adrenal axis under certain experimental conditions.

scholarly journals Dependence of EMG Responses Evoked by Imposed Wrist Displacements on Pre-existing Activity in the Stretched Muscles

1984 ◽  
Vol 11 (2) ◽  
pp. 272-280 ◽  
Author(s):  
W. Bedingham ◽  
W.G. Tatton
Keyword(s):  
Background Activity ◽  
Human Subjects ◽  
Maximum Voluntary Contraction ◽  
Voluntary Contraction ◽  
Emg Activity ◽  
Onset Latency ◽  
Normal Human ◽  
Motoneuron Activity ◽  
Movement Parameters ◽  
The Relationship

ABSTRACT:The relationship between the segmented EMG activity in flexor carpi radialis evoked by imposed angular wrist displacement was studied with respect to the level of pre-existing background activity in 30 normal human subjects. Input-output response planes demonstrate that the magnitude of the Ml & M2-3 segments is dependent on both the displacement parameters and the level of pre-existing EMG activity in the stretched muscle. If the level of background activity exceeded 4-5% of the maximum voluntary contraction, the onset latency of the M1 segment and duration of the Ml and the M2-3 segments remained constant (within ± 2 msec) for different magnitudes of step load displacements, despite marked variation in the range of the displacement’s amplitude, duration, velocity, and acceleration. We propose that the dependency of the relationship between reflex magnitude and imposed movement parameters on tonic motoneuron activity, as represented by pre-existing EMG levels, may reflect an automatic adjustment mechanism that could be utilized in servo compensation of movements requiring markedly different force levels.

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