Illusion caused by vibration of muscle spindles reveals an involvement of muscle spindle inputs in regulating isometric contraction of masseter muscles

2012 ◽  
Vol 108 (9) ◽  
pp. 2524-2533 ◽  
Author(s):  
Taisuke Tsukiboshi ◽  
Hajime Sato ◽  
Yuto Tanaka ◽  
Mitsuru Saito ◽  
Hiroki Toyoda ◽  
...  
Keyword(s):  
Isometric Contraction ◽  
Regression Line ◽  
Muscle Spindles ◽  
Linear Increase ◽  
Emg Activity ◽  
Reflex Pathways ◽  
Closed Position ◽  
Bite Pressure ◽  
Masseter Muscles ◽  
Ramp Load

Spindle Ia afferents may be differentially involved in voluntary isometric contraction, depending on the pattern of synaptic connections in spindle reflex pathways. We investigated how isometric contraction of masseter muscles is regulated through the activity of their muscle spindles that contain the largest number of intrafusal fibers among skeletal muscle spindles by examining the effects of vibration of muscle spindles on the voluntary isometric contraction. Subjects were instructed to hold the jaw at resting position by counteracting ramp loads applied on lower molar teeth. In response to the increasing-ramp load, the root mean square (RMS) of masseter EMG activity almost linearly increased under no vibration, while displaying a steep linear increase followed by a slower increase under vibration. The regression line of the relationship between the load and RMS was significantly steeper under vibration than under no vibration, suggesting that the subjects overestimated the ramp load and excessively counteracted it as reflected in the emergence of bite pressure. In response to the decreasing-ramp load applied following the increasing one, the RMS hardly decreased under vibration unlike under no vibration, leading to a generation of bite pressure even after the offset of the negative-ramp load until the vibration was ceased. Thus the subjects overestimated the increasing rate of the load while underestimating the decreasing rate of the load, due to the vibration-induced illusion of jaw opening. These observations suggest that spindle Ia/II inputs play crucial roles both in estimating the load and in controlling the isometric contraction of masseter muscles in the jaw-closed position.

Influence of submaximal isometric contractions of the hamstrings on electromyography activity and force while functioning as hip extensors

2020 ◽  
pp. 1-8
Author(s):  
Dasom Oh ◽  
Wootaek Lim
Keyword(s):  
Prone Position ◽  
Supine Position ◽  
Isometric Contraction ◽  
Muscle Length ◽  
Biceps Femoris ◽  
Emg Activity ◽  
Isometric Contractions ◽  
Significant Difference ◽  
Extension Force ◽  
Long Head

BACKGROUND: Although the medial and lateral hamstrings are clearly distinct anatomically and have different functions in the transverse plane, they are often considered as one muscle during rehabilitation. OBJECTIVE: The purpose of the study was to compare the electromyographic (EMG) activity between the prone position and the supine position during maximal isometric contraction and to additionally confirm the effect of submaximal isometric contractions on EMG activity of medial and lateral hamstrings, and force. METHODS: In the prone position, EMG activities of the long head of biceps femoris (BFLH) and semitendinosus (ST) were measured during the maximal isometric contraction. In the supine position, hip extension force with EMG activity were measured during the maximal and the submaximal isometric contractions. RESULTS: EMG activity in the prone position was significantly decreased in the supine position. In the supine position, there was a significant difference between the BFLH and ST during the maximal isometric contraction, but not during the submaximal isometric contractions. CONCLUSIONS: The dependence on the hamstrings could be relatively lower during hip extensions. When the medial and lateral hamstrings are considered separately, the lateral hamstrings may show a more active response, with increased muscle length, in clinical practice.

Speech-Motor Equivalence in Aging Subjects

1987 ◽  
Vol 64 (2) ◽  
pp. 635-638 ◽  
Author(s):  
Michael P. Rastatter ◽  
Richard A. Mc Guire ◽  
Laurel Bushong ◽  
Michele Loposky
Keyword(s):  
Muscle Function ◽  
The Elderly ◽  
The Other ◽  
Elderly Subjects ◽  
Emg Activity ◽  
Facial Muscle ◽  
Motor Equivalence ◽  
Children And Young Adults ◽  
Masseter Muscles ◽  
Speech Motor

The peak amplitude of EMG activity was measured from the orbicularis oris superior (OOS), orbicularis oris inferior (OOI), and masseter muscles for three normal, geriatric women (range 70 to 75 yr.) and compared with prior data for a group of normal, 4- and 8-yr.-old children and young adults (range 21 to 29 yr.) The elderly groups' variability across the three muscles paralleled that of the 4-yr.-olds, suggesting that speech-motor equivalence returns to an earlier level of operation in aging speakers. Also, the elderly subjects evidenced reduced levels of average peak EMG activity as compared to those of the other groups. This finding was interpreted as reflecting a loss of general muscle function, a possible concomitant of facial muscle atrophy that accompanies advanced age.

Visual Input Effect on EMG Activity of Sternocleidomastoid and Masseter Muscles in Healthy Subjects and in Patients with Myogenic Cranio-Cervical-Mandibular Dysfunction

CRANIO® ◽  
1998 ◽  
Vol 16 (3) ◽  
pp. 168-184 ◽  
Author(s):  
Rodolfo Miralles ◽  
Saúl Valenzuela ◽  
Pamela Ramirez ◽  
Hugo Santander ◽  
Carmen Palazzi ◽  
...  
Keyword(s):  
Healthy Subjects ◽  
Visual Input ◽  
Emg Activity ◽  
Masseter Muscles

scholarly journals Relationship between Biomechanical Characteristics of Spinal Manipulation and Neural Responses in an Animal Model: Effect of Linear Control of Thrust Displacement versus Force, Thrust Amplitude, Thrust Duration, and Thrust Rate

2013 ◽  
Vol 2013 ◽  
pp. 1-12 ◽  
Author(s):  
William R. Reed ◽  
Dong-Yuan Cao ◽  
Cynthia R. Long ◽  
Gregory N. Kawchuk ◽  
Joel G. Pickar
Keyword(s):  
Force Control ◽  
Spinal Manipulation ◽  
Muscle Spindles ◽  
Threshold Value ◽  
Linear Increase ◽  
Neural Responses ◽  
Lumbar Muscle ◽  
Low Amplitude ◽  
Animal Preparation ◽  
Muscle Spindle Activity

High velocity low amplitude spinal manipulation (HVLA-SM) is used frequently to treat musculoskeletal complaints. Little is known about the intervention’s biomechanical characteristics that determine its clinical benefit. Using an animal preparation, we determined how neural activity from lumbar muscle spindles during a lumbar HVLA-SM is affected by the type of thrust control and by the thrust's amplitude, duration, and rate. A mechanical device was used to apply a linear increase in thrust displacement or force and to control thrust duration. Under displacement control, neural responses during the HVLA-SM increased in a fashion graded with thrust amplitude. Under force control neural responses were similar regardless of the thrust amplitude. Decreasing thrust durations at all thrust amplitudes except the smallest thrust displacement had an overall significant effect on increasing muscle spindle activity during the HVLA-SMs. Under force control, spindle responses specifically and significantly increased between thrust durations of 75 and 150 ms suggesting the presence of a threshold value. Thrust velocities greater than 20–30 mm/s and thrust rates greater than 300 N/s tended to maximize the spindle responses. This study provides a basis for considering biomechanical characteristics of an HVLA-SM that should be measured and reported in clinical efficacy studies to help define effective clinical dosages.

scholarly journals Muscle endurance is greater for old men compared with strength-matched young men

2005 ◽  
Vol 99 (3) ◽  
pp. 890-897 ◽  
Author(s):  
Sandra K. Hunter ◽  
Ashley Critchlow ◽  
Roger M. Enoka
Keyword(s):  
Isometric Contraction ◽  
Perceived Exertion ◽  
Young Men ◽  
Similar Rate ◽  
Voluntary Contraction ◽  
Rating Of Perceived Exertion ◽  
Emg Activity ◽  
Task Failure ◽  
Submaximal Contraction ◽  
Old Men

The purpose was to compare the time to task failure for a sustained isometric contraction performed at a submaximal intensity with the elbow flexor muscles by young and old men who were matched for strength. Eight young men (18–31 yr) and eight old men (67–76 yr) sustained an isometric contraction at 20% of maximal voluntary contraction (MVC) torque until the target torque could no longer be achieved for at least 5 s. The maximal torque exerted at the wrist was similar for the young and old men before the fatiguing task (65.9 ± 8.0 vs. 65.4 ± 8.7 N·m; P > 0.05), and they experienced similar reductions in MVC torque after the fatiguing contraction (31.4 ± 10.6%; P < 0.05). The time to task failure was longer for the old men (22.6 ± 7.4 min) compared with the strength-matched young men (13.0 ± 5.2 min; P < 0.05), despite each group sustaining a similar torque during the fatiguing contraction ( P > 0.05). The increases in torque fluctuations, electromyographic (EMG) bursting activity, and heart rate were greater for young men compared with the old men, and they were less at task failure for the old men ( P < 0.05). Mean arterial pressure increased at a similar rate for both groups of men ( P > 0.05), whereas the averaged EMG activity and rating of perceived exertion reached similar values at task failure for the young and old men ( P > 0.05). These findings indicate that the longer time to task failure for the old men when performing the submaximal contraction was not due the absolute target torque exerted during the contraction.

An Experiment to Test Generalization of Feedback from Frontalis EMG

1980 ◽  
Vol 50 (1) ◽  
pp. 27-31 ◽  
Author(s):  
Alan Le Boeuf
Keyword(s):  
Training Session ◽  
Relaxation Technique ◽  
Emg Activity ◽  
Baseline Session ◽  
Feedback Group ◽  
Emg Feedback ◽  
Leg Extensors ◽  
Masseter Muscles

60 subjects participated in a test of the effectiveness of frontalis EMG feedback as a generalized relaxation technique. The experiment was performed in two parts. In the first part, 30 subjects were randomly allocated to a group receiving frontalis EMG feedback ( n = 10), a group receiving non-contingent feedback ( n = 10) and a group instructed to relax themselves ( n = 10). Each group received one baseline session and five training sessions. EMG measurements from the frontalis, trapezius and masseter muscles taken prior to and immediately after the final training session indicated that the frontalis feedback group was more effective in lowering frontalis and masseter EMG activity (though not trapezius activity) than the controls. The second part of the experiment Was identical to the first with the exception that the subsidiary muscle sites were the forearm and leg extensors. The results showed that frontalis feedback was no more effective than controls in lowering the EMG levels of these muscles.

EMG Activity of Orbicularis Oris Superior, Orbicularis Oris Inferior, and Masseter Muscles of Mild and Moderate Articulatory Disordered Children

1987 ◽  
Vol 64 (3) ◽  
pp. 725-726 ◽  
Author(s):  
Michael Rastatter ◽  
Richard Mc Guire ◽  
Bruce Blair
Keyword(s):  
Peak Amplitude ◽  
Emg Activity ◽  
Normal Children ◽  
Masseter Muscles

The peak amplitude of EMG activity was measured from the orbicularis oris superior, orbicularis oris inferior, and masseter muscles for 3 mild and 3 moderately articulatory disordered and 3 normal children. The three groups showed similar levels of average peak EMG activity and variance across the three muscles, suggesting that the disordered children were free to vary their patterns of activity for these muscles when repeating a series of syllable tokens.

scholarly journals The Effects of Different Vibration Frequencies, Amplitudes and Contraction Levels on Lower Limb Muscles during Graded Isometric Contractions Superimposed on Whole Body Vibration Stimulation

2018 ◽  
Author(s):  
Amit N. Pujari ◽  
Richard D. Neilson ◽  
Marco Cardinale
Keyword(s):  
Muscle Contraction ◽  
Isometric Contraction ◽  
Whole Body Vibration ◽  
Lower Limbs ◽  
Whole Body ◽  
Emg Activity ◽  
Isometric Contractions ◽  
Body Vibration ◽  
Neuromuscular Activity ◽  
Co Activation

AbstractBackgroundIndirect vibration stimulation i.e. whole body vibration or upper limb vibration, has been suggested increasingly as an effective exercise intervention for sports and rehabilitation applications. However, there is a lack of evidence regarding the effects of whole body vibration (WBV) stimulation superimposed to graded isometric contractions superimposed on. For this scope, we investigated the effects of WBV superimposed to graded isometric contractions in the lower limbs on muscle activation. We also assessed the agonist-antagonist co-activation during this type of exercise.Twelve healthy volunteers were exposed to WBV superimposed to graded isometric contractions, at 20, 40, 60, 80 and 100% of the maximum voluntary contractions (V) or just isometric contractions performed on a custom designed horizontal leg press Control (C). Tested stimulation consisted of 30Hzand 50Hz frequencies and 0.5mm and 1.5mm amplitudes. Surface electromyographic activity of Vastus Lateralis (VL), Vastus Medialis (VM) and Biceps Femoris (BF) were measured during V and C conditions. Co-contraction activity of agonist-antagonist muscles was also quantified. The trials were performed in random order.ResultsBoth the prime mover, (VL) and the antagonist, (BF) displayed significantly higher (P < 0.05) EMG activity with the V than the C condition. For both the VL and BF, the increase in mean EMGrms values depended on the frequency, amplitude and muscle contraction level with 50Hz-0.5mm stimulation inducing the largest neuromuscular activity. 50Hz-0.5mm V condition also led to co-activation ratios significantly (P< 0.05) higher at 40, 80 and 100% of MVC than the C condition.ConclusionsOur results show that the isometric contraction superimposed on vibration stimulation leads to higher neuromuscular activity compared to isometric contraction alone in the lower limbs. Compared to the control condition, the vibratory stimulation leads to higher agonist-antagonist co-activation of the muscles around the knee joint in all vibration conditions and effort levels. The combination of vibration magnitude (frequency and amplitude) and the level of muscle contraction affect neuromuscular activity rather than vibration frequency alone. Results of this study suggest that more parameters need to be taken into consideration when designing vibration exercise programs for sports and rehabilitation purposes.

Activation of Peripheral GABAA Receptors Inhibits Temporomandibular Joint–Evoked Jaw Muscle Activity

1999 ◽  
Vol 81 (4) ◽  
pp. 1966-1969 ◽  
Author(s):  
Brian E. Cairns ◽  
Barry J. Sessle ◽  
James W. Hu
Keyword(s):  
Receptor Antagonist ◽  
Temporomandibular Joint ◽  
Gabaa Receptors ◽  
Muscle Activity ◽  
Mustard Oil ◽  
Emg Activity ◽  
Dose Response Relationship ◽  
Jaw Muscle ◽  
Nociceptive Information ◽  
Masseter Muscles

Activation of peripheral GABAA receptors inhibits temporomandibular joint–evoked jaw muscle activity. We have previously shown that injection of mustard oil or glutamate into rat temporomandibular joint (TMJ) tissues, an experimental model of acute TMJ injury, can reflexly induce a prolonged increase in the activity of both digastric (jaw-opener) and masseter (jaw-closer) muscles. In this study, GABA was applied to the TMJ region by itself or in combination with glutamate, and the magnitude of evoked jaw muscle electromyographic (EMG) activity was measured. Application of GABA alone to the TMJ region did not evoke significant jaw muscle EMG activity when compared with normal saline controls. In contrast, co-application of GABA and glutamate into the TMJ region decreased the magnitude of glutamate-evoked EMG activity. This GABA-mediated inhibition of glutamate-evoked EMG activity followed an inverse dose-response relationship with an estimated median inhibitory dose (ID50) of 0.17 ± 0.05 (SE) μmol and 0.031 ± 0.006 μmol for the digastric and masseter muscles, respectively. Co-administration of the GABAA receptor antagonist bicuculline (0.05 μmol) but not the GABABreceptor antagonist phaclofen (0.05 or 0.15 μmol) reversed the suppressive actions of GABA, indicating that this action of GABA may be mediated by peripheral GABAA receptors located within the TMJ region. Our results suggest that activation of peripheral GABAA receptors located within the TMJ region could act to decrease the transmission of nociceptive information.

scholarly journals Assessment of Masticatory Muscle Function in Patients with Bilateral Complete Cleft Lip and Palate and Posterior Crossbite by means of Electromyography

2020 ◽  
Vol 2020 ◽  
pp. 1-7
Author(s):  
Liliana Szyszka-Sommerfeld ◽  
Agata Budzyńska ◽  
Mariusz Lipski ◽  
Sławomir Kulesza ◽  
Krzysztof Woźniak
Keyword(s):  
Muscle Activity ◽  
Muscle Function ◽  
Cleft Lip ◽  
Cleft Lip And Palate ◽  
Emg Activity ◽  
Masticatory Muscle ◽  
Temporalis Muscle ◽  
Posterior Crossbite ◽  
Electrical Potentials ◽  
Masseter Muscles

Aim. The aim of this study was to evaluate the electrical activity of the masticatory muscles in children with a bilateral complete cleft lip and palate (BCCLP) and posterior crossbite as well as in noncleft subjects with no malocclusion. Another purpose of the study was to examine the possible factors associated with this muscle activity. Methods. The study included 52 children with mixed dentition and Class I occlusions (20 patients with nonsyndromic BCCLP and 32 subjects with no clefts). All the cleft patients had posterior crossbite. The surface electromyography (sEMG) was used to identify the electrical potentials of the temporalis and masseter muscles. The electromyographical (EMG) recordings were taken with a DAB-Bluetooth Instrument (zebris Medical GmbH, Germany) at rest and during maximum voluntary clenching (MVC). The relationships between muscle EMG activity and independent variables were identified through multivariate logistic regression analysis. Results. The EMG activity of the temporalis muscles at rest was significantly higher in BCCLP patients with malocclusion in comparison with the noncleft subjects with normal occlusion. During MVC, significantly lower electrical potentials of the temporalis and masseter muscles were observed in cleft patients compared to the noncleft group. The presence of BCCLP, unilateral posterior crossbites, increased vertical overlap, and increased overjet are factors strongly associated with higher temporalis muscle EMG activity at rest. Conclusion. The use of surface electromyography in imaging muscle function showed that children with BCCLP and posterior crossbite exhibited altered masticatory muscle potentials at rest and during clenching. The presence of unilateral posterior crossbites, increased vertical overlap, and increased overjet had a significant impact on temporalis muscle activity in cleft patients. This knowledge is important in the aspect of early and proper diagnosis and orthodontic treatment of malocclusions, thereby achieving correct occlusion and improvement in muscle function.

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