scholarly journals Electromyographic Analysis of Exercises on a Gymnastic Horse and a Walking Horse: A Pilot Study

2021 ◽  
Vol 11 (23) ◽  
pp. 11352
Author(s):  
Barbora Pyšková ◽  
Tereza Nováková ◽  
Radka Bačáková ◽  
Miloslav Vilímek
Keyword(s):  
Experimental Study ◽  
Pilot Study ◽  
Analysis Of Variance ◽  
Human Body ◽  
Muscle Activity ◽  
Maximal Voluntary Contraction ◽  
Voluntary Contraction ◽  
Electromyographic Activity ◽  
Electromyographic Analysis

In studies testing the effect of hippotherapy on the human body, no one has yet compared the involvement of the same specific muscles in exercises on a gymnastic (pommel) horse vs. a walking horse. To improve the correct riding seat and to compare the differences in electromyographic activity, we conducted an experimental study to measure the activity of selected muscles on a set of probands of both sexes during three exercises on a gymnastic horse vs. a walking horse. We measured the activity of eight selected muscles, expressed as the percentage value of the maximal voluntary contraction. Maximal voluntary contraction of each muscle was electromyographically measured using Janda’s strength muscle test. These values were used as a standard for values obtained from exercising on a gymnastic horse and a walking horse. The effect of the studied factors was tested by analysis of variance. The muscle activity was statistically significantly affected by the studied factors. It was higher when riding a living horse than a gymnastic horse and in females compared to males. Although the exercises on a gymnastic horse generated lower muscle activity than those on a walking horse, there was a variation among individual muscles that justified further study.

Accessory muscle activity contributes to the variation in time to task failure for different arm postures and loads

2007 ◽  
Vol 102 (3) ◽  
pp. 1000-1006 ◽  
Author(s):  
Thorsten Rudroff ◽  
Benjamin K. Barry ◽  
Amy L. Stone ◽  
Carolyn J. Barry ◽  
Roger M. Enoka
Keyword(s):  
Mean Arterial Pressure ◽  
Arterial Pressure ◽  
Muscle Activity ◽  
Maximal Voluntary Contraction ◽  
Force Transducer ◽  
Voluntary Contraction ◽  
Time To Failure ◽  
Elbow Flexors ◽  
Accessory Muscle ◽  
Position Task

Time to failure and electromyogram activity were measured during two types of sustained submaximal contractions with the elbow flexors that required each subject to exert the same net muscle torque with the forearm in two different postures. Twenty men performed the tasks, either by maintaining a constant force while pushing against a force transducer (force task), or by supporting an equivalent load while maintaining a constant elbow angle (position task). The time to failure for the position task with the elbow flexed at 1.57 rad and the forearm horizontal was less than that for the force task (5.2 ± 2.6 and 8.8 ± 3.6 min, P = 0.003), whereas it was similar when the forearm was vertical (7.9 ± 4.1 and 7.8 ± 4.5 min, P = 0.995). The activity of the rotator cuff muscles was greater during the position tasks (25.1 ± 10.1% maximal voluntary contraction) compared with the force tasks (15.2 ± 5.4% maximal voluntary contraction, P < 0.001) in both forearm postures. However, the rates of increase in electromyogram of the accessory muscles and mean arterial pressure were greater for the position task only when the forearm was horizontal ( P < 0.05), whereas it was similar for the elbow flexors. These findings indicate that forearm posture influences the difference in the time to failure for the two fatiguing contractions. When there was a difference between the two tasks, the task with the briefer time to failure involved greater rates of increase in accessory muscle activity and mean arterial pressure.

scholarly journals Fatigue-induced adjustment in antagonist coactivation by old adults during a steadiness task

2016 ◽  
Vol 120 (9) ◽  
pp. 1039-1046 ◽  
Author(s):  
Christopher J. Arellano ◽  
David Caha ◽  
Joseph E. Hennessey ◽  
Ioannis G. Amiridis ◽  
Stéphane Baudry ◽  
...  
Keyword(s):  
Maximal Voluntary Contraction ◽  
Failure Time ◽  
Voluntary Contraction ◽  
Matching Task ◽  
Electromyographic Activity ◽  
Time To Failure ◽  
Old Adults ◽  
Before And After ◽  
Wrist Flexors ◽  
Maximal Voluntary Contraction Torque

The purpose of this study was to determine the adjustments in the level of coactivation during a steadiness task performed by young and old adults after the torque-generating capacity of the antagonist muscles was reduced by a fatiguing contraction. Torque steadiness (coefficient of variation) and electromyographic activity of the extensor and flexor carpi radialis muscles were measured as participants matched a wrist extensor target torque (10% maximum) before and after sustaining an isometric contraction (30% maximum) with wrist flexors to task failure. Time to failure was similar ( P = 0.631) for young (417 ± 121 s) and old (452 ± 174 s) adults. The reduction in maximal voluntary contraction torque (%initial) for the wrist flexors after the fatiguing contraction was greater ( P = 0.006) for young (32.5 ± 13.7%) than old (21.8 ± 6.6%) adults. Moreover, maximal voluntary contraction torque for the wrist extensors declined for old (−13.7 ± 12.7%; P = 0.030), but not young (−5.4 ± 13.8%; P = 0.167), adults. Torque steadiness during the matching task with the wrist extensors was similar before and after the fatiguing contraction for both groups, but the level of coactivation increased after the fatiguing contraction for old ( P = 0.049) but not young ( P = 0.137) adults and was twice the amplitude for old adults ( P = 0.002). These data reveal that old adults are able to adjust the amount of antagonist muscle activity independent of the agonist muscle during steady submaximal contractions.

Altered reflex sensitivity after repeated and prolonged passive muscle stretching

1999 ◽  
Vol 86 (4) ◽  
pp. 1283-1291 ◽  
Author(s):  
Janne Avela ◽  
Heikki Kyröläinen ◽  
Paavo V. Komi
Keyword(s):  
Maximal Voluntary Contraction ◽  
Large Diameter ◽  
Compound Action Potential ◽  
Muscle Spindles ◽  
Voluntary Contraction ◽  
Creatine Kinase Activity ◽  
Triceps Surae ◽  
Electromyographic Activity ◽  
Zero Crossing ◽  
Maximal Mass

Experiments were carried out to test the effect of prolonged and repeated passive stretching (RPS) of the triceps surae muscle on reflex sensitivity. The results demonstrated a clear deterioration of muscle function immediately after RPS. Maximal voluntary contraction, average electromyographic activity of the gastrocnemius and soleus muscles, and zero crossing rate of the soleus muscle (recorded from 50% maximal voluntary contraction) decreased on average by 23.2, 19.9, 16.5, and 12.2%, respectively. These changes were associated with a clear immediate reduction in the reflex sensitivity; stretch reflex peak-to-peak amplitude decreased by 84.8%, and the ratio of the electrically induced maximal Hoffmann reflex to the maximal mass compound action potential decreased by 43.8%. Interestingly, a significant ( P < 0.01) reduction in the stretch-resisting force of the measured muscles was observed. Serum creatine kinase activity stayed unaltered. This study presents evidence that the mechanism that decreases the sensitivity of short-latency reflexes can be activated because of RPS. The origin of this system seems to be a reduction in the activity of the large-diameter afferents, resulting from the reduced sensitivity of the muscle spindles to repeated stretch.

scholarly journals Osteoarthrosis: Analyze of the Molar Bite Force, Thickness and Masticatory Efficiency

2020 ◽  
Vol 121 (2) ◽  
pp. 87-95
Author(s):  
Mariah Acioli Righetti ◽  
Oswaldo Luiz Stamato Taube ◽  
Marcelo Palinkas ◽  
Lígia Maria Napolitano Gonçalves ◽  
Danilo Stefani Esposto ◽  
...  
Keyword(s):  
Muscle Activity ◽  
Muscle Thickness ◽  
Voluntary Contraction ◽  
Bite Force ◽  
Electromyographic Activity ◽  
Temporal Muscle ◽  
Significance Level ◽  
Masticatory Efficiency ◽  
Linear Envelope ◽  
The Right

Osteoarthrosis is a disorder of synovial joints, resulting from destruction of the cartilage and subchondral bone. The present study is aimed to investigate the molar bite force, thickness and efficiency of the masseter and temporalis muscles of subjects with osteoarthrosis. A total of forty-eight subjects participated in the study. They were distributed into two groups: with osteoarthrosis (n=24) and asymptomatic controls (n=24). Subjects were analyzed on the basis of maximal molar bite force (right and left side), thickness (mandibular rest and dental clenching in maximal voluntary contraction) and electromyographic activity of masticatory cycles through the linear envelope integral in habitual (raisins and peanuts) and non-habitual (Parafilm M) chewing of the masseter and temporalis muscles. All the data were analyzed statistically using t-test with a significance level of p≤0.05. There was no difference between groups in maximal molar bite force, muscle thickness and non-habitual chewing. Differences were found on the raisins (p=0.02) and peanuts (p=0.05) chewing for right temporal muscle, with reduced masticatory muscle efficiency in osteoarthrosis subjects. This study showed that osteoarthrosis induces negative changes in habitual chewing, highlighting the efficiency of the right temporalis muscles. The greater temporal muscle activity in subjects with osteoarthrosis may compromise chewing and consequently the nutritional status of adult subjects.

scholarly journals Examination of the bioelectrical activity of the masticatory muscles during Angle’s Class II division 2 therapy with an activator

2014 ◽  
Vol 71 (12) ◽  
pp. 1116-1122
Author(s):  
Djordje Petrovic ◽  
Sanja Vujkov ◽  
Branislava Petronijevic ◽  
Ivan Sarcev ◽  
Igor Stojanac
Keyword(s):  
Maximal Voluntary Contraction ◽  
Orthodontic Treatment ◽  
Class Ii ◽  
Masticatory Muscles ◽  
Voluntary Contraction ◽  
First Year ◽  
Bioelectrical Activity ◽  
Study Group ◽  
Electromyographic Activity ◽  
Angle Class

Background/Aim. The muscles of the orofacial region have great influence on the development of dentition and occlusion formation. It is known that improper function of these muscles is one of the major etiological factors in malocclusion. A correlation between function disorders of orofacial muscle and occlusion disorders has been confirmed, as well as a correlation between the bioelectric activity of the masticatory muscles, recorded by electromyography, and bite force upon maximal voluntary contraction of these muscles. The aim of the study was to analyze the bioelectriacal activity of temporal and masseter muscles. Methods. The sample consisted of 100 subjects of both sexes, divided into the control group (n = 30) with neutral and complete dental arches, and the study group (n = 70) of patients with distal occlusion. Electromyographic measurement of bioelectric potentials in all the subjects was conducted for the examined muscles in the physiologic rest position, central mandible occlusion, and during maximal voluntary contraction of muscles and saliva swallowing, in Angle Class I and II/2 occlusal relation-ships, prior to treatment, after one year of the orthodontic treatment and after the treatment with an activator. Results. Comparing the values of thebioelectrical activity in the control and the study group before the treatment, a decreased muscle activity was established in all the three positions in the study group. After the first year of orthodontic treatment the results showed an elevation in the bioelectrical activity in both muscles. After treatment with an activator, the bioelectrical activity in both muscles in the study group was higher than before the treatment, as it is confirmed by a positive highly significant coefficient of correlation. Conclusion. In all the three measured positions of the mandible with Angle Class II/2 malocclusion, bioelectrical activity was lowest at baseline and increased during the first year of treatment, and at the end of the treatment it partially reduced close to the approximate values in normal occlusion. Research on electromyographic activity of masticatory muscles is useful in everyday clinical practice, especially in present distinctive skeletal discrepancy before, during and after orthodontic treatment, if on the bases of the results we can evaluate the treatment, but also determine the start and duration of the retention period and retention device type.

Contractile speed and EMG changes during fatigue of sustained maximal voluntary contractions

1983 ◽  
Vol 50 (1) ◽  
pp. 313-324 ◽  
Author(s):  
B. Bigland-Ritchie ◽  
R. Johansson ◽  
O. C. Lippold ◽  
J. J. Woods
Keyword(s):  
Nerve Stimulation ◽  
Maximal Voluntary Contraction ◽  
Time Course ◽  
Muscle Activation ◽  
Neuromuscular Block ◽  
Voluntary Contraction ◽  
Percentage Change ◽  
Electromyographic Activity ◽  
Excitation Rate ◽  
Voluntary Contractions

Measurements were made from the human adductor pollicis muscle of force, contractile speed, and electromyographic activity (EMG) before, during, and after maximal isometric voluntary contractions sustained for 60 s. The use of brief test periods of maximal nerve stimulation with single shocks or trains of shocks enabled various muscle mechanical properties to be studied throughout each contraction. Electrical activity was measured after rectification and smoothing of the surface potentials and also by counting the total number of potentials per unit time from a population of motor units using fine wire intramuscular electrodes. During a 60-s maximal voluntary contraction, the force fell by 30-50%. Throughout the experiment the voluntary force matched that produced by supramaximal tetanic nerve stimulation. This indicated that, with sufficient practice, full muscle activation could be maintained by voluntary effort. However, the amplitude of the smoothed, rectifed EMG and the rate of spike counts declined. Since no evidence for neuromuscular block was found, the decline in EMG and spike counts was attributed to a progressive reduction of the neural drive from the central nervous system, despite maintained maximum effort. After the prolonged voluntary contractions twitch duration was prolonged, mainly as a result of slowing in relaxation rate. Twitch summation in unfused tetani increased. Both the maximum rate of relaxation and the time course of force decay declined by 50-70%. Similar changes were seen in both voluntary contractions and in test periods of stimulation. The percentage change in muscle contractile speed measured by these parameters approximately equaled the percentage change in the surface EMG measured simultaneously. It is concluded that 1) during a 60-s sustained maximal voluntary contraction there is a progressive slowing of contraction speed such that the excitation rate required to give maximal force generation is reduced, 2) the simultaneous decline in EMG may be due to a continuous reduction in motoneuron discharge rate, and 3) the EMG decline may not necessarily contribute to force loss.

scholarly journals Analysis of electromyographic changes in gastrocnemius muscle on exposure to 24 h of dry supine immersion

2021 ◽  
Vol 65 ◽  
pp. 33-37
Author(s):  
N Manu ◽  
A Agarwal ◽  
VK Malhotra
Keyword(s):  
Maximal Voluntary Contraction ◽  
Gastrocnemius Muscle ◽  
Simulated Microgravity ◽  
Voluntary Contraction ◽  
Total Power ◽  
Electromyographic Activity ◽  
Median Frequency ◽  
Strong Positive Correlation ◽  
Short Term Exposure ◽  
Submaximal Contraction

Introduction: Under microgravity, changes are observed in both structure and content of the gravity-dependent muscles. This may result in disuse atrophy and muscle weakening. However, changes have not been described in the short term exposure of 24 h. Examination of changes in electromyographic activity of the gastrocnemius muscle, on exposure to 24 h of simulated microgravity using dry supine immersion (DSI), was the desired objective of the study. Material and Methods: Ten healthy volunteers were exposed to 24 h of simulated microgravity using DSI. The force generated by maximal voluntary contraction of isometric plantar flexion of ankle was recorded. Electromyography (EMG) of the gastrocnemius corresponding to more than 80% of maximal voluntary isometric contraction (labeled as submaximal contraction) was recorded pre- and post-exposure to 24 h of DSI. Results: Time domain analysis of the surface EMG of gastrocnemius during submaximal contraction revealed a significant increase in mean integrated EMG (iEMG) amplitude (effect size = 0.73, P = 0.031) following 24 h DSI. Power spectral analysis showed a significant decrease in mean frequency (MNF) (P = 0.043) and median frequency (MDF) (P = 0.024) after 24 h DSI. No significant changes were observed in total power, mean power (MNP), and maximal voluntary contraction. A very strong negative correlation was noted between iEMG, MNF, and MDF for the duration of submaximal voluntary contraction (R = −0.827 and −0.810, P = 0.003 and 0.004, respectively); whereas, a very strong positive correlation was noted between iEMG and MNP (R = 0.911, P = 0.002). Conclusion: The findings of the study point toward muscle weakening seen by an early onset of muscle fatigue in anti-gravity muscles as early as 24 h of exposure to microgravity. The same may be borne in mind even during very short duration human space missions.

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