Hip Adduction Does not Affect VMO EMG Amplitude or VMO:VL Ratios during a Dynamic Squat Exercise

2006 ◽  
Vol 15 (3) ◽  
pp. 195-205 ◽  
Author(s):  
Michelle Boling ◽  
Darin Padua ◽  
J. Troy Blackburn ◽  
Meredith Petschauer ◽  
Christopher Hirth
Keyword(s):  
Outcome Measures ◽  
Knee Flexion ◽  
Healthy Subjects ◽  
Vastus Lateralis ◽  
Test Session ◽  
Surface Emg ◽  
Knee Extension ◽  
Emg Amplitude ◽  
Squat Exercise ◽  
History Of

Context:Clinicians commonly attempt to facilitate vastus medialis oblique (VMO) activity by instructing patients to squeeze a ball between their knees during squatting exercises.Objective:To determine whether VMO activation amplitude and the VMO to vastus lateralis (VL) activation ratio (VMO:VL) were altered when performing active hip adduction during a dynamic squat exercise.Design:Single test session.Participants:Fifteen healthy subjects, with no history of knee pain, volunteered for this study.Intervention:Surface EMG of the VMO, VL, and hip adductor (ADD) muscles were recorded while subjects performed 10 consecutive squats against their body weight through a range of 0° to 90° of knee flexion. Subjects performed the squat exercises during two different conditions: (1) active hip adduction and (2) no hip adduction.Main Outcome Measures:Average VMO EMG amplitude and VMO:VL ratio were determined during the knee flexion (0° to 90°) and knee extension (90° to 0°) phases of the squat exercise.Results:Active hip adduction did not significantly change VMO amplitude or VMO:VL ratio during the knee flexion or knee extension phases of the dynamic squat exercise.Conclusions:Based on these results, we conclude that VMO amplitude and the VMO: VL ratio are not influenced by performing active hip adduction during a dynamic squat exercise in healthy subjects.

Medial and Lateral Quadriceps Muscle Activity during Weight-Bearing Knee Extension Exercise

1998 ◽  
Vol 7 (4) ◽  
pp. 248-257 ◽  
Author(s):  
Gilbert M. Willett ◽  
Jason B. Paladino ◽  
Kory M. Barr ◽  
Jill N. Korta ◽  
Gregory M. Karst
Keyword(s):  
Vastus Lateralis ◽  
Weight Bearing ◽  
Quadriceps Muscle ◽  
Surface Emg ◽  
Knee Extension ◽  
Emg Activity ◽  
Exercise Condition ◽  
Elastic Resistance ◽  
Activity Performance ◽  
History Of

The purpose of this study was to determine the effect of weight-bearing terminal knee extension (WBKE) on normalized mean electromyographic (EMG) activity of the vastus medialis oblique (VMO) and vastus lateralis (VL) and the VMO/VL ratio. Sixteen subjects with no history of knee dysfunction participated. Surface EMG data were recorded from the VMO and VL of subjects' test legs as they performed the WBKE exercise under four conditions, three involving elastic resistance and one involving no elastic resistance. EMG data were normalized relative to a maximal isometric quadriceps contraction, and overall mean VMO and VL activity and the VMO/VL ratio were determined for all conditions. The three conditions utilizing elastic resistance showed higher mean VMO and VL activity than the no-resistance condition. The VMO/ VL ratio was not significantly altered during any exercise condition as compared to maximal, quadriceps setting exercise. WBKE against elastic resistance was superior to the same exercise without resistance for generating mean VMO and VL activity. Performance of the WBKE, regardless of the position of lower extremity rotation, does not selectively activate the VMO apart from, or to a greater degree than, the VL.

scholarly journals Fatigue and the Electromechanical Efficiency of the Vastus Medialis and Vastus Lateralis Muscles

2008 ◽  
Vol 43 (2) ◽  
pp. 152-156 ◽  
Author(s):  
Kyle T. Ebersole ◽  
David M. Malek
Keyword(s):  
Repeated Measures ◽  
Vastus Lateralis ◽  
Knee Injuries ◽  
Surface Emg ◽  
Vastus Lateralis Muscle ◽  
Vastus Medialis ◽  
Mechanical Responses ◽  
Repeated Measures Design ◽  
Emg Amplitude ◽  
History Of

Abstract Context: The relationship between the amplitudes of the mechanomyographic (MMG) and electromyographic (EMG) signals has been used to examine the “electromechanical efficiency” (EME) of normal and diseased muscle. The EME may help us to better understand the neuromuscular relationship between the vastus medialis and vastus lateralis muscles. Objective: To examine the EME of the vastus medialis and vastus lateralis muscles during a fatiguing task. Design: Repeated-measures design. Setting: Research laboratory. Patients or Other Participants: Ten healthy males (age  =  23.2 ± 1.2 years) with no history of knee injury. Intervention(s): Seventy-five consecutive, maximal concentric isokinetic leg extensions at a velocity of 180°/s. Main Outcomes Measure(s): Bipolar surface EMG electrodes were placed over the vastus medialis and vastus lateralis muscles, with an MMG contact sensor placed adjacent to the superior EMG electrode on each muscle. The MMG and EMG amplitude values (root mean squares) were calculated for each of the 75 repetitions and normalized to the highest value from the 75 repetitions. The EME was expressed as the ratio of the log-transformed normalized MMG amplitude to the normalized EMG amplitude. For each muscle, the linear relationship for the normalized-group mean EME was determined across the 75 repetitions. Results: Linear regression indicated decreases in torque (R2  =  .96), vastus medialis EME (R2  =  .73), and vastus lateralis EME (R2  = .73). The slopes for the vastus medialis and vastus lateralis EME were not different (P > .10). Conclusions: The similarities in the fatigue-induced decreases in EME for the vastus medialis and vastus lateralis muscles suggested that symmetry was present between the muscles in the electric and mechanical responses to repeated, maximal muscle actions. The EME measurements may provide a unique insight into the influence of fatigue on the contractile properties of skeletal muscle, including alterations that occur to the intrinsic electric and mechanical components. The EME may be useful in assessing and quantifying clinically relevant asymmetries in vastus medialis and vastus lateralis muscle function in those with knee injuries.

The frequency of alternate muscle activity is associated with the attenuation in muscle fatigue

2006 ◽  
Vol 101 (3) ◽  
pp. 715-720 ◽  
Author(s):  
Motoki Kouzaki ◽  
Minoru Shinohara
Keyword(s):  
Muscle Fatigue ◽  
Muscle Activity ◽  
Healthy Subjects ◽  
Vastus Lateralis ◽  
Rectus Femoris ◽  
Knee Extension ◽  
Voluntary Contraction ◽  
Sustained Contraction ◽  
Low Level ◽  
Before And After

Alternate muscle activity between synergist muscles has been demonstrated during low-level sustained contractions [≤5% of maximal voluntary contraction (MVC) force]. To determine the functional significance of the alternate muscle activity, the association between the frequency of alternate muscle activity during a low-level sustained knee extension and the reduction in knee extension MVC force was studied. Forty-one healthy subjects performed a sustained knee extension at 2.5% MVC force for 1 h. Before and after the sustained knee extension, MVC force was measured. The surface electromyogram was recorded from the rectus femoris (RF), vastus lateralis (VL), and vastus medialis (VM) muscles. The frequency of alternate muscle activity for RF-VL, RF-VM, and VL-VM pairs was determined during the sustained contraction. The frequency of alternate muscle activity ranged from 4 to 11 times/h for RF-VL (7.0 ± 2.0 times/h) and RF-VM (7.0 ± 1.9 times/h) pairs, but it was only 0 to 2 times/h for the VL-VM pair (0.5 ± 0.7 times/h). MVC force after the sustained contraction decreased by 14% ( P < 0.01) from 573.6 ± 145.2 N to 483.3 ± 130.5 N. The amount of reduction in MVC force was negatively correlated with the frequency of alternate muscle activity for the RF-VL and RF-VM pairs ( P < 0.001 and r = 0.65 for both) but not for the VL-VM pair. The results demonstrate that subjects with more frequent alternate muscle activity experience less muscle fatigue. We conclude that the alternate muscle activity between synergist muscles attenuates muscle fatigue.

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.

ELECTROMYOGRAPHIC ANALYSIS OF LEG EXTENSION EXERCISE DURING DIFFERENT ANKLE AND KNEE POSITIONS

2015 ◽  
Vol 15 (02) ◽  
pp. 1540037 ◽  
Author(s):  
GUIDO BELLI ◽  
LUCA VITALI ◽  
MATTEO BOTTEGHI ◽  
LEYDI NATALIA VITTORI ◽  
ELISABETTA PETRACCI ◽  
...  
Keyword(s):  
Knee Flexion ◽  
Vastus Lateralis ◽  
Pain Syndrome ◽  
Knee Extension ◽  
Maximal Voluntary Isometric Contraction ◽  
Leg Extension ◽  
Isometric Knee Extension ◽  
Medial Rotation ◽  
Electromyographic Analysis ◽  
Main Factor

The imbalance between vastus medialis oblique (VMO) and vastus lateralis (VL) strength is one of the main factor for patellofemoral pain syndrome (PFPS) onset, related to improper alignment of the patella. The aim of this paper is to investigate the effects of knee flexion, knee rotation and ankle flexion attitudes on the activity of the VMO and VL muscles during unilateral maximal voluntary isometric contraction (MIVC) of the quadriceps femoris. Eighteen healthy subjects volunteered for the study. Five conditions for two different knee flexion angles (90°; 30°) were tested using leg extension machine: Neutral (N) condition, maximal knee medial rotation (MR), maximal knee lateral rotation (LR), maximal ankle plantarflexion (PF) and maximal ankle dorsiflexion (DF). Data were normalized in order to calculate the normalized VMO/VL ratio. The normalized VMO/VL ratio for all the conditions occurred at 90° of knee flexion was higher than the same conditions at 30° of knee flexion (p = 0.02). No statistical differences between conditions at the same knee angle and for angle x condition interaction were observed (p > 0.05). These findings suggest that knee flexion should be the first variable to be managed during isometric knee extension movement performed by leg extension machine, in order to increase VMO/VL ratio.

Between-muscle differences in the adaptation to experimental pain

2014 ◽  
Vol 117 (10) ◽  
pp. 1132-1140 ◽  
Author(s):  
François Hug ◽  
Paul W. Hodges ◽  
Wolbert van den Hoorn ◽  
Kylie Tucker
Keyword(s):  
Elastic Modulus ◽  
Vastus Lateralis ◽  
Experimental Pain ◽  
Rectus Femoris ◽  
Quadriceps Muscle ◽  
Knee Extension ◽  
Shear Elastic Modulus ◽  
Emg Amplitude ◽  
Extension Force ◽  
Muscle Stress

This study aimed to determine whether muscle stress (force per unit area) can be redistributed between individual heads of the quadriceps muscle when pain is induced into one of these heads. Elastography was used to measure muscle shear elastic modulus (an index of muscle stress). Electromyography (EMG) was recorded from vastus lateralis (VL), vastus medialis (VM), and rectus femoris (RF). In experiment I ( n = 20), participants matched a knee extension force, and thus any reduction of stress within the painful muscle would require compensation by other muscles. In experiment II ( n = 13), participants matched VL EMG amplitude and were free to vary external force such that intermuscle compensation would be unnecessary to maintain the experimental task. In experiments I and II, pain was induced by injection of hypertonic saline into VM or RF. Experiment III aimed to establish whether voluntary drive to the individual muscles could be controlled independently. Participants ( n = 13) were asked to voluntarily reduce activation of VM or RF while maintaining knee extension force. During VM pain, there was no change in shear elastic modulus ( experiments I and II) or EMG amplitude of VM ( experiment II). In contrast, RF pain was associated with a reduction in RF elastic modulus ( experiments I and II: −8 to −17%) and EMG amplitude ( experiment II). Participants could voluntarily reduce EMG amplitude of RF ( −26%; P = 0.003 ) but not VM ( experiment III). These results highlight between-muscle differences in adaptation to pain that might be explained by their function (monoarticular vs. biarticular) and/or the neurophysiological constraints associated to their activation.

A Gender Comparison of Central and Peripheral Neuromuscular Function After Exercise

2012 ◽  
Vol 21 (3) ◽  
pp. 209-217 ◽  
Author(s):  
Ashley Stern ◽  
Chris Kuenze ◽  
Daniel Herman ◽  
Lindsay D. Sauer ◽  
Joseph M. Hart
Keyword(s):  
Outcome Measures ◽  
Motor Evoked Potentials ◽  
Cruciate Ligament ◽  
Peak Torque ◽  
Surface Emg ◽  
Knee Extension ◽  
Ligament Injury ◽  
Exercise Protocol ◽  
Peripheral Muscle ◽  
Increase Risk

Context:Central and peripheral muscle fatigue during exercise may exacerbate neuromuscular factors that increase risk for noncontact anterior cruciate ligament injury.Objective:To compare lower extremity motor-evoked potentials (MEPs), muscle strength, and electromyography (EMG) activation after an exercise protocol.Design:Pretest, posttest group comparison.Setting:University laboratory.Participants:34 healthy volunteers (17 female, age = 21.9 ± 2.3 years, weight = 77.8 ± 3.0 kg, height = 171.1 ± 6.6 cm, and 17 male, age = 23.4 ± 6.5 years, weight = 81.6 ± 3.3 kg, height = 179.6 ± 7.3 cm).Intervention:A standardized 30-min exercise protocol that involved 5 repeated cycles of uphill walking, body-weight squatting, and step-ups.Main Outcome Measures:Quadriceps and hamstring MEP amplitude (mV) and transmission velocity normalized to subject height (m/s) were elicited via transcranial magnetic stimulation and measured via surface EMG. Quadriceps and hamstring peak EMG activation (% MVIC) and peak torque (Nm/kg) were measured during MVICs. Separate ANCOVAs were used to compare groups after exercise while controlling for baseline measurement.Results:At baseline, males exhibited significantly greater knee-extension torques (males = 2.47 ± 0.68 Nm/kg, females = 1.95 ± 0.53 Nm/kg; P = .036) and significantly higher hamstring MEP amplitudes (males = 223.5 ± 134.0 mV, females = 89.3 ± 77.6 mV; P = .007). Males exhibited greater quadriceps MEP amplitude after exercise than females (males = 127.2 ± 112.7 mV, females = 32.3 ± 34.9 mV; P = .016).Conclusions:Males experienced greater peripheral neuromuscular changes manifested as more pronounced reductions in quadriceps torque after exercise. Females experienced greater central neuromuscular changes manifested as more pronounced reduction in quadriceps MEP amplitude. Reduced central neural drive of the quadriceps coupled with knee-extension torque preservation after exercise may increase risk of knee injury in females.

Task dependency of motor adaptations to an acute noxious stimulation

2014 ◽  
Vol 111 (11) ◽  
pp. 2298-2306 ◽  
Author(s):  
François Hug ◽  
Paul W. Hodges ◽  
Kylie Tucker
Keyword(s):  
Elastic Modulus ◽  
Degrees Of Freedom ◽  
Isometric Force ◽  
Vastus Lateralis ◽  
Knee Extension ◽  
Noxious Stimulation ◽  
Shear Elastic Modulus ◽  
Emg Amplitude ◽  
Single Leg Squat ◽  
Control Pain

This study explored motor adaptations in response to an acute noxious stimulation during three tasks that differed in the number of available degrees of freedom. Fifteen participants performed three isometric force-matched tasks (single leg knee extension, single leg squat, and bilateral leg squat) in three conditions (Control, Pain, and Washout). Pain was induced by injection of hypertonic saline into the vastus medialis muscle (VM; left leg). Supersonic shear imaging was used to measure muscle shear elastic modulus as this is considered to be an index of muscle stress. Surface electromyography (EMG) was recorded bilaterally from six muscles to assess changes in neural strategies. During tasks with fewer degrees of freedom (knee extension and single leg squat task), there was no change in VM EMG amplitude or VM shear elastic modulus. In contrast, during the bilateral leg squat, VM (−32.9 ± 15.8%; P < 0.001) and vastus lateralis (−28.7 ± 14.8%; P < 0.001) EMG amplitude decreased during Pain. This decrease in activation was associated with reduced VM shear elastic modulus (−17.6 ± 23.3%; P = 0.029) and reduced force produced by the painful leg (−10.0 ± 10.2%; P = 0.046). This work provides evidence that when an obvious solution is available to decrease stress on painful tissue, this option is selected. It confirms the fundamental assumption that motor adaptations to pain aim to alter load on painful tissue to protect for further pain and/or injury. The lack of adaptation observed during force-matched tasks with fewer degrees of freedom might be explained by the limited potential to redistribute stress or a high cost induced by such a compensation.

scholarly journals The Surface EMG Characteristics between Erector Spinae and Vastus Lateralis during Bending Forward and Squatting Down Tasks

2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
Jinzhuang Xiao ◽  
Junmin Gao ◽  
Hongrui Wang ◽  
Kun Liu ◽  
Xincai Yang
Keyword(s):  
Theoretical Basis ◽  
Healthy Subjects ◽  
Vastus Lateralis ◽  
Surface Emg ◽  
Physical Activities ◽  
Erector Spinae ◽  
Median Frequency ◽  
Low Back ◽  
The Right ◽  
Daily Physical Activities

Bending forward and squatting down are two common physical tasks in everyday life and at work. This study determined the sEMG characteristics between erector spinae and vastus lateralis during bending forward and squatting down tasks by analyzing the regularity of variation in sEMG frequency domain index-median frequency (MNF) in healthy subjects. The results indicate that sEMG activities in erector spinae are significantly higher than those in the right vastus lateralis during bending forward task. Instead, in squatting down task, sEMG activities in the right vastus lateralis are significantly greater than those in erector spinae. It also shows that the fatigue degree of low back caused by trunk bending is much deeper than that by squatting down. The ratio scope of one-order fitting values of MNF between erector spinae and vastus lateralis ranges from 0.87 to 1.72 among 80% of subjects during bending forward task and ranges from 0.31 to 1.11 during squatting down task. This study provides certain theoretical basis for using the strength of low back in a proper way to avoid getting it hurt in daily physical activities.

Influence of Hip Position on Electromyographic and Torque Productions in the Knee

1993 ◽  
Vol 2 (1) ◽  
pp. 26-34 ◽  
Author(s):  
Scott J. Black ◽  
Michael L. Woodhouse ◽  
Stephen Suttmiller ◽  
Larry Shall
Keyword(s):  
Supine Position ◽  
Knee Flexion ◽  
Knee Extension ◽  
Emg Activity ◽  
Sitting Position ◽  
Surface Electrodes ◽  
Recreational Athletes ◽  
Emg Amplitude ◽  
Torque Values ◽  
Flexion And Extension

The effects of hip position on thigh electromyographic (EMG) activity and knee torque were evaluated. Twenty-four recreational athletes (12 males and 12 females) volunteered to participate. Subjects were tested isokinetically at 30°/s in sitting and supine positions both concentrically and eccentrically during knee flexion and extension. Gravity-corrected torques (N·m) were obtained for all tests. EMG amplitude (mV) was collected via surface electrodes. Torque values were significantly greater (p<.05) for knee flexion in the sitting position when compared to the supine. EMG activity did not change relative to hip position but typically increased (p<.05) during concentric trials. Knee extension torque and EMG activity did not change during sitting or supine positions. Results indicated that the sitting position had statistically significant advantages over the supine position for producing greater hamstring torque and maintaining similar levels of EMG output during isokinetic knee flexion.

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