Comparison of Force and Peak EMG during a Maximal Voluntary Isometric Contraction at Selected Angles in the Range of Motion for Knee Extension

1996 ◽  
Vol 83 (3) ◽  
pp. 976-978 ◽  
Author(s):  
Roger M. Zabik ◽  
Mary L. Dawson
Keyword(s):  
Isometric Contraction ◽  
Knee Flexion ◽  
Vastus Lateralis ◽  
Rectus Femoris ◽  
Knee Extension ◽  
Vastus Medialis ◽  
Joint Motion ◽  
Maximal Voluntary Isometric Contraction ◽  
Motor Recruitment ◽  
Larger Sample

For 5 adults maximal isometric strength at 110°, 90°, 70°, 50°, and 30° of knee flexion for the vastus medialis, rectus femoris, and vastus lateralis varied across angles but EMG responses were similar. That motor recruitment patterns were similar throughout the range of joint motion requires replication on a larger sample.

The Effects of Ankle Position on Torque and Muscle Activity of the Knee Extensor During Maximal Isometric Contraction

2020 ◽  
Vol 29 (1) ◽  
pp. 37-42
Author(s):  
Dae-Hyun Kim ◽  
Jin-Hee Lee ◽  
Seul-Min Yu ◽  
Chang-Man An
Keyword(s):  
Isometric Contraction ◽  
Vastus Lateralis ◽  
Plantar Flexion ◽  
Isometric Exercise ◽  
Rectus Femoris ◽  
Peak Torque ◽  
Emg Activity ◽  
Neutral Position ◽  
Vastus Medialis ◽  
Maximal Voluntary Isometric Contraction

Context: It is very important to empirically determine the optimal ankle position for the quadriceps femoris (QF) strengthening during isometric exercises. Objective: To examine the effect of different ankle positions on torque and electromyography (EMG) activity of QF during maximal isometric contraction. Study Design: Within-subject repeated measures. Setting: University laboratory. Participants: Thirty-six healthy volunteers (15 males and 21 females). Main Outcome Measures: The isometric strength of the QF was measured at 3 different ankle positions: active dorsiflexion (AD), active plantar flexion (AP), and neutral position (NP). Simultaneously, 3 different ankle positions were assessed for EMG activity of the vastus medialis, vastus lateralis, and rectus femoris muscles during maximal voluntary isometric contraction. Results: The peak torque per body weight and average peak torque were significantly higher in AD than in AP and NP (P < .01). The vastus medialis and rectus femoris maximal voluntary isometric contraction EMG activity were significantly higher in AD than in AP and NP (P < .01). The vastus lateralis maximal voluntary isometric contraction EMG activity was significantly higher in AD than in AP and NP (P < .01), and was significantly higher in AP than in NP (P < .05). Conclusions: These results indicate that the 3 different ankle positions affect the QF torque and EMG activity. In particular, AD position may be more efficient for improving QF strength than AP and NP position. Future studies should prove whether long-term duration QF isometric exercise effects muscle strength and functional performance in different ankle positions.

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.

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.

VMO:VL Ratios and Torque Comparisons at Four Angles of Knee Flexion

1995 ◽  
Vol 4 (4) ◽  
pp. 264-272 ◽  
Author(s):  
Teddy W. Worrell ◽  
Steven Connelly ◽  
John Hilvert
Keyword(s):  
Measurement Error ◽  
Future Study ◽  
Isometric Contraction ◽  
Knee Flexion ◽  
Vastus Medialis ◽  
Maximal Voluntary Isometric Contraction ◽  
Knee Position ◽  
Significant Difference ◽  
Intraclass Correlations ◽  
Asymptomatic Subjects

The purpose of this study was to determine the intrasession and intersessionreliabilityof EMG vastus medialis oblique:vastus lateralis (VMO:VL) ratios at four knee positions (0, 45, 60, and 90°) at 100 and 60% of maximal voluntary isometric contraction (MVIC). Once reliability was established, the second purpose was to determine VMO:VL ratios and torque at each knee position. Thirty-two subjects participated in two sessions; 19 subjects were tested at 100% MVIC and 13 were tested at .60% MVIC. Results revealed the following intraclass correlations: 100% MVIC intrasession .40-.80, intersession .40-.70; 60% MVIC intrasession .60-.90, intersession .50-.80. A significant difference in torque occurred at all knee positions except 60 versus 90°. No significant difference existed in VMO:VL ratios at the four positions of knee flexion. Pain and measurement error significantly increased during 100% MVIC testing. It was concluded that no selective VMO recruitment occurred as revealed by the VMO: VL ratios in asymptomatic subjects. Future study is needed that reports EMG reliability data during exercises that theorize selective VMO recruitment.

Ultrasound Imaging of the Vastus Intermedius and Vastus Medialis Oblique Thickness for Assessment of Early Torque Development During Knee Extension

2020 ◽  
Vol 10 (7) ◽  
pp. 1557-1561
Author(s):  
Jaeho Yang ◽  
Yong Woo An ◽  
Eunwook Chang
Keyword(s):  
Isometric Contraction ◽  
Muscle Thickness ◽  
Peak Torque ◽  
Quadriceps Muscle ◽  
Knee Extension ◽  
Vastus Medialis ◽  
Maximal Voluntary Isometric Contraction ◽  
Rate Of Torque Development ◽  
Vastus Intermedius ◽  
Torque Development

The purpose of this study was to investigate relationships between knee extension torque (rate of torque development and peak torque) and quadriceps muscle thickness in healthy males and females. Thirty-six recreationally active and healthy individuals participated in the study. Portable ultrasound was used to image the dominant side of each quadriceps muscle (rectus femoris, vastus intermedius, vastus lateralis, vastus medialis, vastus medialis oblique). After muscle thickness measurement, participants performed knee extension maximal voluntary isometric contraction. Rate of torque development was calculated from 0 to 50 (RTD50) and 0 to 200 (RTD200) milliseconds after onset of torque generation and peak torque was defined as maximum torque during maximal voluntary isometric contraction trials. A higher RTD50 value was found to be associated with greater vastus intermedius and vastus medialis oblique thicknesses, and a higher RTD200 with the thickness of all quadriceps muscles (p < 0.05). Finally, vastus medialis and vastus medialis oblique thicknesses were associated with a higher peak torque (p < 0.05). According to these results, the findings suggest to coaches that vastus intermedius and vastus medialis oblique thicknesses are critical to torque development during the early phase of knee extension contraction (RTD50), which is essential for executing athletic tasks and preventing injuries.

scholarly journals Electromyographic Comparison of Five Lower-Limb Muscles between Single- and Multi-Joint Exercises among Trained Men

2021 ◽  
pp. 56-61
Author(s):  
Nicolay Stien ◽  
Atle Hole Saeterbakken ◽  
Vidar Andersen
Keyword(s):  
Resistance Training ◽  
Vastus Lateralis ◽  
Gluteus Maximus ◽  
Rectus Femoris ◽  
Biceps Femoris ◽  
Knee Extension ◽  
Knee Extensors ◽  
Vastus Medialis ◽  
Leg Press ◽  
Emg Amplitude

Resistance-training exercises can be classified as either single- or multi-joint exercises and differences in surface electromyography (EMG) amplitude between the two training methods may identify which muscles can benefit from either training modality. This study aimed to compare the surface EMG amplitude of five hip- and knee extensors during one multi-joint (leg press) and two single-joint exercises (knee extension and kickback). Fifteen resistance-trained men completed one familiarization session to determine their unilateral six repetitions maximum (6RM) in the three exercises. During the following experimental session, EMG amplitudes of the vastus lateralis, vastus medialis, rectus femoris, gluteus maximus and biceps femoris of the left leg were measured while performing three repetitions on their respective 6RM loads. The multi-joint exercise leg press produced higher EMG amplitude of the vastus lateralis (ES = 0.92, p = 0.003) than the single-joint exercise knee extension, whereas the rectus femoris demonstrated higher EMG amplitude during the knee extension (ES = 0.93, p = 0.005). The biceps femoris EMG amplitude was higher during the single-joint exercise kickback compared to the leg press (ES = 2.27, p < 0.001), while no significant differences in gluteus maximus (ES = 0.08, p = 0.898) or vastus medialis (ES = 0.056, p = 0.025 were observed between exercises. The difference in EMG amplitude between single- and multi-joint exercises appears to vary depending on the specific exercises and the muscle groups tested. Leg press is a viable and time-efficient option for targeting several hip- and knee extensors during resistance training of the lower limbs, but the single-joint exercises may be preferable for targeting the rectus femoris and biceps femoris.

Repeated Kicking Actions in Karate: Effect on Technical Execution in Elite Practitioners

2016 ◽  
Vol 11 (3) ◽  
pp. 363-369 ◽  
Author(s):  
Federico Quinzi ◽  
Valentina Camomilla ◽  
Alberto Di Mario ◽  
Francesco Felici ◽  
Paola Sbriccoli
Keyword(s):  
Knee Flexion ◽  
Muscle Activation ◽  
Vastus Lateralis ◽  
Linear Regression Analysis ◽  
Knee Kinematics ◽  
Rectus Femoris ◽  
Knee Extension ◽  
Median Frequency ◽  
Flexion Extension ◽  
Hip Abduction

Purpose:Training in martial arts is commonly performed by repeating a technical action continuously for a given number of times. This study aimed to investigate if the repetition of the task alters the proper technical execution, limiting the training efficacy for the technical evaluation during competition. This aim was pursued analyzing lower-limb kinematics and muscle activation during repeated roundhouse kicks.Methods:Six junior karate practitioners performed continuously 20 repetitions of the kick. Hip and knee kinematics and sEMG of vastus lateralis, biceps (BF), and rectus femoris were recorded. For each repetition, hip abduction–adduction and flexion–extension and knee flexion–extension peak angular displacements and velocities, agonist and antagonist muscle activation were computed. Moreover, to monitor for the presence of myoelectric fatigue, if any, the median frequency of the sEMG was computed. All variables were normalized with respect to their individual maximum observed during the sequence of kicks. Linear regressions were fitted to each normalized parameter to test its relationship with the repetition number.Results:Linear-regression analysis showed that, during the sequence, the athletes modified their technique: Knee flexion, BF median frequency, hip abduction, knee-extension angular velocity, and BF antagonist activation significantly decreased. Conversely, hip flexion increased significantly.Conclusions:Since karate combat competitions require proper technical execution, training protocols combining severe fatigue and technical actions should be carefully proposed because of technique adaptations. Moreover, trainers and karate masters should consider including specific strength exercises for the BF and more generally for knee flexors.

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.

scholarly journals Regional and muscle-specific adaptations in knee extensor hypertrophy using flywheel versus conventional weight-stack resistance exercise

2019 ◽  
Vol 44 (8) ◽  
pp. 827-833 ◽  
Author(s):  
Tommy R. Lundberg ◽  
Maria T. García-Gutiérrez ◽  
Mirko Mandić ◽  
Mats Lilja ◽  
Rodrigo Fernandez-Gonzalo
Keyword(s):  
Resistance Exercise ◽  
Muscle Hypertrophy ◽  
Vastus Lateralis ◽  
Knee Extensor ◽  
Rectus Femoris ◽  
Knee Extension ◽  
Knee Extensors ◽  
Cross Sectional ◽  
Proximal Site ◽  
Before And After

This study compared the effects of the most frequently employed protocols of flywheel (FW) versus weight-stack (WS) resistance exercise (RE) on regional and muscle-specific adaptations of the knee extensors. Sixteen men (n = 8) and women (n = 8) performed 8 weeks (2–3 days/week) of knee extension RE employing FW technology on 1 leg (4 × 7 repetitions), while the contralateral leg performed regular WS training (4 × 8–12 repetitions). Maximal strength (1-repetition maximum (1RM) in WS) and peak FW power were determined before and after training for both legs. Partial muscle volume of vastus lateralis (VL), vastus medialis (VM), vastus intermedius (VI), and rectus femoris (RF) were measured using magnetic resonance imaging. Additionally, quadriceps cross-sectional area was assessed at a proximal and a distal site. There were no differences (P > 0.05) between FW versus WS in muscle hypertrophy of the quadriceps femoris (8% vs. 9%), VL (10% vs. 11%), VM (6% vs. 8%), VI (5% vs. 5%), or RF (17% vs. 17%). Muscle hypertrophy tended (P = 0.09) to be greater at the distal compared with the proximal site, but there was no interaction with exercise method. Increases in 1RM and FW peak power were similar across legs, yet the increase in 1RM was greater in men (31%) than in women (20%). These findings suggest that FW and WS training induces comparable muscle-specific hypertrophy of the knee extensors. Given that these robust muscular adaptations were brought about with markedly fewer repetitions in the FW compared with WS, it seems FW training can be recommended as a particularly time-efficient exercise paradigm.

scholarly journals Midterm outcome and strength assessment after proximal rectus femoris refixation in athletes

2021 ◽  
Author(s):  
Maximilian Hinz ◽  
Stephanie Geyer ◽  
Felix Winden ◽  
Alexander Braunsperger ◽  
Florian Kreuzpointner ◽  
...  
Keyword(s):  
Knee Flexion ◽  
Rectus Femoris ◽  
Knee Extension ◽  
Harris Hip Score ◽  
Postoperative Results ◽  
Postoperative Result ◽  
Strength Assessment ◽  
Competitive Athletes ◽  
Hip Flexion

Abstract Purpose Proximal rectus femoris avulsions (PRFA) are relatively rare injuries that occur predominantly among young soccer players. The aim of this study was to evaluate midterm postoperative results including strength potential via standardized strength measurements after proximal rectus femoris tendon refixation. It was hypothesized that the majority of competitive athletes return to competition (RTC) after refixation of the rectus femoris tendon without significant strength or functional deficits compared to the contralateral side. Methods Patients with an acute (< 6 weeks) PRFA who underwent surgical refixation between 2012 and 2019 with a minimum follow-up of 12 months were evaluated. The outcome measures compiled were the median Tegner Activity Scale (TAS) and mean RTC time frames, Harris Hip Score (HHS), Hip and Groin Outcome Score (HAGOS) subscales, International Hip Outcome Tool-33 (iHOT-33), and Visual Analog Scale (VAS) for pain. In addition, a standardized isometric strength assessment of knee flexion, knee extension, and hip flexion was performed to evaluate the functional result of the injured limb in comparison to the uninjured side. Results Out of 20 patients, 16 (80%) patients were available for final assessment at a mean follow-up of 44.8 ± SD 28.9 months. All patients were male with 87.5% sustaining injuries while playing soccer. The average time interval between trauma and surgery was 18.4 ± 8.5 days. RTC was possible for 14 out of 15 previously competitive athletes (93.3%) at a mean 10.5 ± 3.4 months after trauma. Patients achieved a high level of activity postoperatively with a median (interquartile range) TAS of 9 (7–9) and reported good to excellent outcome scores (HHS: 100 (96–100); HAGOS: symptoms 94.6 (89.3–100), pain 97.5 (92.5–100), function in daily living 100 (95–100), function in sport and recreation 98.4 (87.5–100), participation in physical activities 100 (87.5–100), quality of life 83.1 ± 15.6; iHot-33: 95.1 (81.6–99.8)). No postoperative complications were reported. Range of motion, isometric knee flexion and extension, as well as hip flexion strength levels were not statistically different between the affected and contralateral legs. The majority of patients were “very satisfied” (56.3%) or “satisfied” (37.5%) with the postoperative result and reported little pain (VAS 0 (0–0.5)). Conclusion Surgical treatment of acute PRFA yields excellent postoperative results in a young and highly active cohort. Hip flexion and knee extension strength was restored fully without major surgical complications. Level of evidence Retrospective cohort study; III.

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