scholarly journals Exploratory study of electromyographic behavior of the vastus medialis and vastus lateralis at neuromuscular fatigue onset

2014 ◽  
Vol 20 (2) ◽  
pp. 213-220 ◽  
Author(s):  
Cristiano Rocha da Silva ◽  
Danilo de Oliveira Silva ◽  
Deisi Ferrari ◽  
Rúben de Faria Negrão Filho ◽  
Neri Alves ◽  
...  
Keyword(s):  
Exploratory Study ◽  
Vastus Lateralis ◽  
Knee Extension ◽  
Neuromuscular Fatigue ◽  
Isometric Contractions ◽  
Median Frequency ◽  
Vastus Medialis ◽  
Mean Square ◽  
Electromyographic Signal ◽  
The Moment

This study aimed to determine and analyze the neuromuscular fatigue onset by median frequency (MDF) and the root mean square (RMS) behavior of an electromyographic signal (EMG). Eighteen healthy men with no prior knee problems initially performed three maximum voluntary isometric contractions (MVIC). After two days of MVIC test, participants performed a fatiguing protocol in which they performed submaximal knee-extension contractions at 20% and 70% MVIC held to exhaustion. The MDF and RMS values from the EMG signals were recorded from the vastus medialis (VM) and the vastus lateralis (VL). Analysis of the MDF and RMS behavior enabled identification of neuromuscular fatigue onset for VM and VL muscles in 20% and 70% loads. Alterations between the VM and VL in the neuromuscular fatigue onset, at 20% and 70% MVIC, were not significant. These findings suggest that the methodology proposal was capable of indicating minute differences sensible to alterations in the EMG signals, allowing identification of the moment when the MDF and the RMS showed significant changes in behavior. The methodology used was also a viable one for describing and identifying the neuromuscular fatigue onset by means of the analysis of EMG signals.

Reciprocal Coactivation Patterns of the Lateral and Medial Quadriceps and Hamstrings during Low- and Moderate-Speed Isokinetic Movement

1998 ◽  
Vol 7 (3) ◽  
pp. 182-196 ◽  
Author(s):  
Ronald V. Croce ◽  
John P. Miller ◽  
Robert Confessore ◽  
James C. Vailas
Keyword(s):  
Knee Joint ◽  
Female Athletes ◽  
Vastus Lateralis ◽  
Biceps Femoris ◽  
Median Frequency ◽  
Vastus Medialis ◽  
Mean Square ◽  
Joint Movement ◽  
Surface Electrodes ◽  
Emg Patterns

The purpose of this study was to examine coactivation patterns of the lateral and medial quadriceps and the lateral and medial hamstrings during low- and moderate-speed isokinetic movements. Twelve female athletes performed isokinetic knee assessments at 60 and 180°/s. Root mean square electromyographic (rmsEMG) activity and the median frequency of the EMG (mfEMG) were determined by placing bipolar surface electrodes on the vastus lateralis (VL), vastus medialis (VM), biceps femoris (BF), and medial hamstrings (MH). Results of rmsEMG indicated that the VM showed almost twice the coactivation of the VL (p< .05), and that the BF showed almost four times the coactivation of the MH (p <.05). Finally, differences were noted in the mfEMG (p< .05), with the VM displaying different recruitment patterns at 180°/s as an agonist compared to that as an antagonist. Results indicated that when acting as antagonists, the VM and BE display the greatest EMG patterns during isokinetic knee joint movement.

scholarly journals Test-retest reliability of electromyographic signal parameters used to evaluate neuromuscular fatigue in quadriceps femoris muscle

Kinesiology ◽  
2016 ◽  
Vol 48 (2) ◽  
pp. 174-181 ◽  
Author(s):  
Cristiano Rocha da Silva ◽  
Danilo de Oliveira Silva ◽  
Ronaldo Valdir Briani ◽  
Marcella Ferraz Pazzinatto ◽  
Deisi Ferrari ◽  
...  
Keyword(s):  
Vastus Lateralis ◽  
Rectus Femoris ◽  
Neuromuscular Fatigue ◽  
Median Frequency ◽  
Endurance Time ◽  
Retest Reliability ◽  
Emg Signal ◽  
Electromyographic Signal ◽  
Test Retest Reliability ◽  
Voluntary Contractions

The purpose of this study was to analyze the test-retest reliability of the median frequency (MDF) and root mean square (RMS) used to determine the onset of neuromuscular fatigue (NF) during sustained fatiguing contractions of the quadriceps. Eighteen healthy men were tested on two days, and electromyographic (EMG) signals were recorded from the vastus medialis (VM), rectus femoris (RF) and vastus lateralis (VL) during sustained isometric contractions at 20 and 70% of maximum voluntary contractions (MVC) held until exhaustion. The reliability of endurance time was excellent at 20% MVC and poor at 70% MVC. EMG variables were evaluated: (1) at the beginning of the test; (2) at NF; and (3) at the end of the test. The NF time values presented poor reliability. The MDF has shown, in general, poor reliability at 20 and 70% MVC, whereas the RMS reliability presented better results for both loads, especially for RF, followed by the VM and VL muscles. The MDF and RMS values extracted from NF showed poor reliability at 20 and 70% MVC, which suggests caution in using these variables extracted from the EMG signal to determine the onset of NF.

Neuromuscular fatigue development during maximal concentric and isometric knee extensions

2006 ◽  
Vol 100 (3) ◽  
pp. 780-785 ◽  
Author(s):  
Nicolas Babault ◽  
Kevin Desbrosses ◽  
Marie-Sophie Fabre ◽  
Anne Michaut ◽  
Michel Pousson
Keyword(s):  
Root Mean Square ◽  
Vastus Lateralis ◽  
Neuromuscular Fatigue ◽  
Peripheral Fatigue ◽  
Vastus Lateralis Muscle ◽  
Electromyographic Activity ◽  
Median Frequency ◽  
Mean Square ◽  
Fatigue Development ◽  
Frequency Changes

This study aimed to investigate mechanisms of neuromuscular fatigue during maximal concentric and isometric leg extensions inducing similar torque decrements. Nine physically active men performed two separate fatiguing sessions maintained until similar torque decreases were obtained. The first session, only conducted under isokinetic concentric conditions (CON), consisted of three series of 30 maximal voluntary concentric knee extensions (60°/s). The second session, exclusively isometric (ISO), mimicked the torque decreases registered during the CON session while performing three long-lasting ISO contractions. Maximal voluntary torque, activation level (twitch interpolation technique), electromyographic activity (root mean square and median frequency) of the vastus lateralis muscle, and electrically evoked doublet-twitch mechanical properties were measured before and at the end of each of the three series. After the three series, similar torque decrements were obtained for both fatiguing procedures. The total fatiguing contraction durations were not different among procedures. With equivalent voluntary torque decrements, the doublet-twitch amplitude reduction was significantly greater ( P < 0.01) during the two first series of the CON procedure compared with ISO. No difference was observed for the third series. Although no difference was recorded with fatigue for median frequency changes between CON and ISO, activation levels and root mean square values demonstrated greater reductions ( P < 0.05) for all three series during the ISO procedure compared with CON. Performing CON or ISO fatiguing exercises demonstrated different fatigue origins. With CON exercises, peripheral fatigue developed first, followed by central fatigue, whereas with ISO exercises the fatigue pattern was inverted.

scholarly journals Effects of different vibration frequencies, amplitudes and contraction levels on lower limb muscles during graded isometric contractions superimposed on whole body vibration stimulation

2019 ◽  
Vol 6 ◽  
pp. 205566831982746 ◽  
Author(s):  
Amit N Pujari ◽  
Richard D Neilson ◽  
Marco Cardinale
Keyword(s):  
Isometric Contraction ◽  
Vastus Lateralis ◽  
Whole Body Vibration ◽  
Biceps Femoris ◽  
Whole Body ◽  
Isometric Contractions ◽  
Electromyographic Activity ◽  
Mean Square ◽  
Body Vibration ◽  
Neuromuscular Activity

Background Indirect vibration stimulation, i.e., whole body vibration or upper limb vibration, has been investigated increasingly as an exercise intervention for rehabilitation applications. However, there is a lack of evidence regarding the effects of graded isometric contractions superimposed on whole body vibration stimulation. Hence, the objective of this study was to quantify and analyse the effects of variations in the vibration parameters and contraction levels on the neuromuscular responses to isometric exercise superimposed on whole body vibration stimulation. Methods In this study, we assessed the ‘neuromuscular effects’ of graded isometric contractions, of 20%, 40%, 60%, 80% and 100% of maximum voluntary contraction, superimposed on whole body vibration stimulation (V) and control (C), i.e., no-vibration in 12 healthy volunteers. Vibration stimuli tested were 30 Hz and 50 Hz frequencies and 0.5 mm and 1.5 mm amplitude. Surface electromyographic activity of the vastus lateralis, vastus medialis and biceps femoris were measured during V and C conditions with electromyographic root mean square and electromyographic mean frequency values used to quantify muscle activity and their fatigue levels, respectively. Results Both the prime mover (vastus lateralis) and the antagonist (biceps femoris) displayed significantly higher (P < 0.05) electromyographic activity with the V than the C condition with varying percentage increases in EMG root-mean-square (EMGrms) values ranging from 20% to 200%. For both the vastus lateralis and biceps femoris, the increase in mean EMGrms values depended on the frequency, amplitude and muscle contraction level with 50 Hz–0.5 mm stimulation inducing the largest neuromuscular activity. Conclusions These results show that the isometric contraction superimposed on vibration stimulation leads to higher neuromuscular activity compared to isometric contraction alone in the lower limbs. The combination of the vibration frequency with the amplitude and the muscle tension together grades the final neuromuscular output.

Motor units in vastus lateralis and in different vastus medialis regions show different firing properties during low-level, isometric knee extension contraction

2018 ◽  
Vol 58 ◽  
pp. 307-314 ◽  
Author(s):  
Leonardo Mendes Leal de Souza ◽  
Hélio Veiga Cabral ◽  
Liliam Fernandes de Oliveira ◽  
Taian Martins Vieira
Keyword(s):  
Vastus Lateralis ◽  
Motor Units ◽  
Knee Extension ◽  
Vastus Medialis ◽  
Low Level ◽  
Isometric Knee Extension ◽  
Firing Properties

Examining Neuromuscular Control of the Vastus Medialis Oblique and Vastus Lateralis Muscles During Fundamental Dance Movements

2020 ◽  
Vol 24 (4) ◽  
pp. 153-160
Author(s):  
Hannah Weighart ◽  
Noelle Morrow ◽  
Sarah DiPasquale ◽  
Stephen J. Ives
Keyword(s):  
External Rotation ◽  
Vastus Lateralis ◽  
Neuromuscular Control ◽  
Surface Emg ◽  
Knee Extension ◽  
Vastus Medialis ◽  
Important Indicator ◽  
Significant Relationships ◽  
Dance Movements ◽  
Patellofemoral Alignment

Elite dancers have a higher rate of injury than college athletes. This may be due, in part, to improper alignment during dance movements. Electromyography (EMG) can be an important indicator of such activity. This study aimed to examine how turnout (maximal hip external rotation) impacts activation of the vastus medialis oblique (VMO) and vastus lateralis (VL) muscles during fundamental dance movements. Thirty female collegiate dancers were recruited from intermediate and advanced ballet and modern technique classes. Surface EMG was used to examine activation of the VMO and VL during maximal isokinetic knee extension in demi-pliés and sautés in parallel and turned-out positions. The mean VMO:VL ratio was determined as a percentage of the highest repetition of maximal extension. The ratio was significantly lower during parallel sautés (0.921 ± 0.258) in comparison to turned-out sautés (1.008 ± 0.384; p = 0.033) and parallel pliés (1.185 ± 0.509; p = 0.002). No significant relationships were found between the VMO:VL ratio and injury history or predominant style of dance. Further investigation is warranted to examine the relationships between VMO:VL activation, patellofemoral alignment, and risk of pathology during simple and complex dance movements.

Decrease in maximal voluntary contraction by tonic vibration applied to a single synergist muscle in humans

2000 ◽  
Vol 89 (4) ◽  
pp. 1420-1424 ◽  
Author(s):  
Motoki Kouzaki ◽  
Minoru Shinohara ◽  
Tetsuo Fukunaga
Keyword(s):  
Maximal Voluntary Contraction ◽  
Vastus Lateralis ◽  
Rectus Femoris ◽  
Knee Extension ◽  
Voluntary Contraction ◽  
Vastus Medialis ◽  
Force Development ◽  
Ia Afferent ◽  
Before And After ◽  
Integrated Emg

The purpose of the study was to examine the effect of prolonged tonic vibration applied to a single synergist muscle on maximal voluntary contraction (MVC) and maximal rate of force development (dF/d t max). The knee extension MVC force and surface electromyogram (EMG) from the rectus femoris (RF), vastus lateralis (VL), and vastus medialis (VM) during MVC were recorded before and after vibration of RF muscle at 30 Hz for 30 min. MVC, dF/d t max, and the integrated EMG (iEMG) of RF decreased significantly after prolonged tonic vibration in spite of no changes in iEMG of VL and VM. The present results indicate that MVC and dF/d t max may be influenced by the attenuated Ia afferent functions of a single synergist muscle.

scholarly journals Neural and morphological adaptations of vastus lateralis and vastus medialis muscles to isokinetic eccentric training

2014 ◽  
Vol 20 (3) ◽  
pp. 317-324 ◽  
Author(s):  
Rodrigo de Azevedo Franke ◽  
Bruno Manfredini Baroni ◽  
Rodrigo Rodrigues ◽  
Jeam Marcel Geremia ◽  
Fábio Juner Lanferdini ◽  
...  
Keyword(s):  
Training Program ◽  
Vastus Lateralis ◽  
Control Period ◽  
Muscle Thickness ◽  
Knee Extension ◽  
Vastus Medialis ◽  
Eccentric Training ◽  
Rehabilitation Programs ◽  
Morphological Adaptations ◽  
Synergistic Muscles

Vastus lateralis (VL) and vastus medialis (VM) are frequently targeted in conditioning/rehabilitation programs due to their role in patellar stabilization during knee extension. This study assessed neural and muscular adaptations in these two muscles after an isokinetic eccentric training program. Twenty healthy men underwent a four-week control period followed by a 12-week period of isokinetic eccentric training. Ultrasound evaluations of VL and VM muscle thickness at rest and electromyographic evaluations during maximal isometric tests were used to assess the morphological and neural properties, respectively. No morphological and neural changes were found throughout the control period, whereas both muscles showed significant increases in thickness (VL = 6.9%; p < .001 and VM = 15.8%; p < .001) post-training. Significant increases in muscle activity were observed in VM (47.8%; p = .003), but not in VL (19.8%; p > .05) post-training. Isokinetic eccentric training produces neural and greater morphological adaptations in VM compared to VL, which shows that synergistic muscles respond differently to an eccentric isokinetic strength training program

scholarly journals The Residual Effect of Prior Drop Jumps on EMG Parameters of Thigh Muscles during Moderate and Heavy Cycling

2018 ◽  
Vol 2 (85) ◽  
Author(s):  
Neringa Baranauskienė ◽  
Loreta Stasiulė ◽  
Sandra Raubaitė ◽  
Arvydas Stasiulis
Keyword(s):  
Muscle Soreness ◽  
Vastus Lateralis ◽  
Residual Effect ◽  
Vastus Medialis ◽  
Mean Square ◽  
Cycling Exercise ◽  
Delayed Onset ◽  
Concentric Exercise ◽  
Thigh Muscles ◽  
Drop Jumps

Research  background  and  hypothesis.  Prior  eccentric  or  eccentric-concentric  exercise  induces  long  lasting muscle fatigue and delayed onset muscle soreness (DOMS). Moreover, the surface electromyograme sEMG amplitude increases under fatigue conditions. We suppose that prior eccentric – concentric exercise, inducing DOMS, increases EMG amplitude of thigh muscles during constant cycling exercises.Research aim of the study was to assess the residual effect of 100 prior drop jumps (PDJ) on the sEMG of m. vastus lateralis and m. vastus medialis during moderate and heavy intensity cycling exercises. Research methods. On four different days 10 female students performed one increasing and three (control, 45  min and 24 h after 100 drop jumps) moderate and heavy cycling (Ergoline-800, Germany) exercises. The cadence of cycling was 70 rpm. The sEMG of right thigh m. vastus lateralis and m. vastus medialis were continuously recorded during moderate and heavy cycling exercise. Creatine kinasis activity was measured and DOMS was rated 24 h after PDJ. Research results. After 24 h the subjects felt moderate DOMS (5.0 (2.79)) according to 10 point scale. The sEMG root mean square amplitude of m. vastus lateralis significantly increased 24 h after PDJ during moderate, but unaltered during heavy cycling exercise under fatigue conditions (45 min and 24 h after PDJ).Discussion and conclusion. Prior drop jumps seem to have significant residual (within 24 h of recovery) effect on EMG of thigh muscles during moderate cycling exercise in female students.Keywords: delayed onset muscle soreness, constant load, EMG root mean square.

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