scholarly journals A Semi-active Exoskeleton Based on EMGs Reduces Muscle Fatigue When Squatting

2021 ◽  
Vol 15 ◽  
Author(s):  
Zhuo Wang ◽  
Xinyu Wu ◽  
Yu Zhang ◽  
Chunjie Chen ◽  
Shoubin Liu ◽  
...  
Keyword(s):  
Muscle Fatigue ◽  
Vastus Lateralis ◽  
Gluteus Maximus ◽  
Metabolic Cost ◽  
Rectus Femoris ◽  
Elastic Support ◽  
Erector Spinae ◽  
Rigid Support ◽  
Working Environments ◽  
Vastus Intermedius

In dynamic manufacturing and warehousing environments, the work scene made it impossible for workers to sit, so workers suffer from muscle fatigue of the lower limb caused by standing or squatting for a long period of time. In this paper, a semi-active exoskeleton used to reduce the muscle fatigue of the lower limb was designed and evaluated. (i) Background: The advantages and disadvantages of assistive exoskeletons developed for industrial purposes were introduced. (ii) Simulation: The process of squatting was simulated in the AnyBody.7.1 software, the result showed that muscle activity of the gluteus maximus, rectus femoris, vastus medialis, vastus lateralis, vastus intermedius, and erector spinae increased with increasing of knee flexion angle. (iii) Design: The exoskeleton was designed with three working modes: rigid-support mode, elastic-support mode and follow mode. Rigid-support mode was suitable for scenes where the squatting posture is stable, while elastic-support mode was beneficial for working environments where the height of squatting varied frequently.The working environments were identified intelligently based on the EMGs of the gluteus maximus, and quadriceps, and the motor was controlled to switch the working mode between rigid-support mode and elastic-support mode. In follow mode, the exoskeleton moves freely with users without interfering with activities such as walking, ascending and descending stairs. (iv) Experiments: Three sets of experiments were conducted to evaluate the effect of exoskeleton. Experiment one was conducted to measure the surface electromyography signal (EMGs) in both condition of with and without exoskeleton, the root mean square of EMGs amplitude of soleus, vastus lateralis, vastus medialis, gastrocnemius, vastus intermedius, rectus femoris, gluteus maximus, and erector spinae were reduced by 98.5, 97.89, 80.09, 77.27, 96.73, 94.17, 70.71, and 36.32%, respectively, with the assistance of the exoskeleton. The purpose of experiment two was aimed to measure the plantar pressure with and without exoskeleton. With exoskeleton, the percentage of weight through subject's feet was reduced by 63.94, 64.52, and 65.61% respectively at 60°, 90°, and 120° of knee flexion angle, compared to the condition of without exoskeleton. Experiment three was purposed to measure the metabolic cost at a speed of 4 and 5 km/h with and without exoskeleton. Experiment results showed that the average additional metabolic cost introduced by exoskeleton was 2.525 and 2.85%. It indicated that the exoskeleton would not interfere with the movement of the wearer Seriously in follow mode. (v) Conclusion: The exoskeleton not only effectively reduced muscle fatigue, but also avoided interfering with the free movement of the wearer.

scholarly journals Differences in Simulated EMG Activities between a Non-Rotational Shot and an Ordinary Instep Kick Identified by Principal Component Analysis

Proceedings ◽  
2020 ◽  
Vol 49 (1) ◽  
pp. 154
Author(s):  
Tasuku Miyoshi ◽  
Yasuhisa Kamada ◽  
Yoshiyuki Kobayashi
Keyword(s):  
Principal Component Analysis ◽  
Vastus Lateralis ◽  
Gluteus Maximus ◽  
Principal Component ◽  
Rectus Femoris ◽  
Component Analysis ◽  
Vastus Intermedius ◽  
Longus Muscle ◽  
Instep Kick ◽  
Tensor Fasciae Latae

The aim of this study was to clarify the major differences in the electromyographic (EMG) activities in the hip joint required to achieve a non-rotational (NR) shot as compared with an instep kick from the spatiotemporal data. For this purpose, simulated EMG activities obtained from NR shots and instep kicks were analyzed using principal component analysis (PCA). The PCA was conducted using an input matrix constructed from the time-normalized average and the standard deviation of the EMG activities (101 data x (15 muscles; iliacus, gluteus maximus, rectus femoris, biceos femoris, vastus lateralis, vastus medialis, vastus intermedius, semimembranosus, semitendinosus, sartorius, tensor fasciae latae muscle, adductor magnus muscle, adductor longus muscle, gasctrocnemius, and tibialis anterior)). The PCA revealed that the 3rd, 4th and 8th principal component vectors (PCVs) of the 10 generated PCVs were related to achieving the NR shot (p < 0.05).

scholarly journals THE EFFECT OF LOCAL VIBROSTIMULATION ON ELECTROMYOGRAPHY PARAMETERS IN ROWERS

2017 ◽  
Vol 3 ◽  
pp. 325
Author(s):  
Kalvis Ciekurs ◽  
Viesturs Krauksts ◽  
Daina Krauksta ◽  
Baiba Smila ◽  
Aivars Kaupuzs
Keyword(s):  
Biceps Brachii ◽  
Vastus Lateralis ◽  
Gluteus Maximus ◽  
Rectus Femoris ◽  
Biceps Femoris ◽  
Erector Spinae ◽  
Mathematical Statistics ◽  
Triceps Brachii ◽  
The Mean ◽  
Moving Speed

Local vibrostimulation (further in text - LV) is innovation as a part of training method that helps athletes to regain the power and get ready for next training faster. There are many discussions about how to increase moving speed in rowers. Many scientists research the possibilities of increasing moving speed in this sport. The following methods were used in the study: tests – Concept-2, LV manipulations, electromyography and mathematical statistics. The electromyography was made with Biometric LTD. LV manipulations were done to the muscles erector spinae, latisimus dorsi, teres major, teres minor, trapezius, infraspinatus, deltoideus, slenius capitis, triceps brachii, gluteus maximus, semitendinosus, biceps femoris, semimembranosus, castrocnemius, tendo calcaneus, rectus femoris, vastus lateralis, tensor fascia latae, vastus medialis, sarterius, ligamentum patellae, tibialis anterior, rectus abdominis, pectoralis major and biceps brachii. We using 100 Hz frequency, 2 – 4 mm amplitude and different pressure on the muscles. The total LV application time was 5 to 20  min. The obtained data were processed using mathematical statistics. The results: having stated the result difference before LV and after it. The results testify significant improvement of Concept-2 tests results and electromyography results, what is showed by the difference of the mean results. Comparing the results of the rowers of EG and CG they have differences in the left side muscle latissimus dorsi after the t-test where p>0.05, but stating the percentage of the mean result difference of this muscle it was found out that p>0.05 what also shows significant changes in the muscle biopotential (mV).

Muscle-specific atrophy of the quadriceps femoris with aging

2001 ◽  
Vol 90 (6) ◽  
pp. 2070-2074 ◽  
Author(s):  
T. A. Trappe ◽  
D. M. Lindquist ◽  
J. A. Carrithers
Keyword(s):  
Vastus Lateralis ◽  
Rectus Femoris ◽  
Quadriceps Femoris ◽  
Aging Research ◽  
Cross Sectional ◽  
Men And Women ◽  
Younger Women ◽  
Vastus Intermedius ◽  
Aging Men ◽  
Old Men

We examined the size of the four muscles of the quadriceps femoris in young and old men and women to assess whether the vastus lateralis is an appropriate surrogate for the quadriceps femoris in human studies of aging skeletal muscle. Ten young (24 ± 2 yr) and ten old (79 ± 7 yr) sedentary individuals underwent magnetic resonance imaging of the quadriceps femoris after 60 min of supine rest. Volume (cm3) and average cross-sectional area (CSA, cm2) of the rectus femoris (RF), vastus lateralis (VL), vastus intermedius (VI), vastus medialis (VM), and the total quadriceps femoris were decreased ( P < 0.05) in older compared with younger women and men. However, percentage of the total quadriceps femoris taken up by each muscle was similar ( P > 0.05) between young and old (RF: 10 ± 0.3 vs. 11 ± 0.4; VL: 33 ± 1 vs. 33 ± 1; VI: 31 ± 1 vs. 31 ± 0.4; VM: 26 ± 1 vs. 25 ± 1%). These results suggest that each of the four muscles of the quadriceps femoris atrophy similarly in aging men and women. Our data support the use of vastus lateralis tissue to represent the quadriceps femoris muscle in aging research.

scholarly journals Implementation of a Portable Electromyographic Prototype for the Detection of Muscle Fatigue

Electronics ◽  
2019 ◽  
Vol 8 (6) ◽  
pp. 619 ◽  
Author(s):  
Sandra De la Peña ◽  
Aura Polo ◽  
Carlos Robles-Algarín
Keyword(s):  
Muscle Fatigue ◽  
Muscular Strength ◽  
Vastus Lateralis ◽  
Rectus Femoris ◽  
Skin Surface ◽  
Mean Frequency ◽  
Signal Characteristics ◽  
Dynamic Contractions ◽  
Experienced Fatigue ◽  
Two Parameters

Surface electromyography (sEMG) applied to the sports training area makes possible the observation of fatigue as well as the generation of muscular strength, through the study of changes in signal characteristics, such as peak-to-peak amplitude, mean frequency and median, among others. In this sense, this work presents the design of a portable prototype for the acquisition and processing of electromyographic (EMG) signals aimed at the detection of muscle fatigue in athletes. Using two Bluetooth Bee modules, a wireless communication was performed in order to send the muscular electrical activity of the skin surface to a user interface developed in LabVIEW. A group of players from the Volleyball team of the Universidad del Magdalena, performed a series of exercise routines with dynamic contractions and as they experienced fatigue, samples were taken of the contractions made. The tests were performed on the vastus lateralis and rectus femoris muscles. The analysis of fatigue under dynamic conditions of the two parameters studied, in frequency and time, showed that it is more pertinent to estimate fatigue indices in the frequency domain.

Muscle coordination in cycling: effect of surface incline and posture

1998 ◽  
Vol 85 (3) ◽  
pp. 927-934 ◽  
Author(s):  
Li Li ◽  
Graham E. Caldwell
Keyword(s):  
Lower Extremity ◽  
High Speed ◽  
Vastus Lateralis ◽  
Activity Patterns ◽  
Gluteus Maximus ◽  
Rectus Femoris ◽  
Biceps Femoris ◽  
Knee Extensors ◽  
Emg Activity ◽  
Muscle Coordination

The purpose of the present study was to examine the neuromuscular modifications of cyclists to changes in grade and posture. Eight subjects were tested on a computerized ergometer under three conditions with the same work rate (250 W): pedaling on the level while seated, 8% uphill while seated, and 8% uphill while standing (ST). High-speed video was taken in conjunction with surface electromyography (EMG) of six lower extremity muscles. Results showed that rectus femoris, gluteus maximus (GM), and tibialis anterior had greater EMG magnitude in the ST condition. GM, rectus femoris, and the vastus lateralis demonstrated activity over a greater portion of the crank cycle in the ST condition. The muscle activities of gastrocnemius and biceps femoris did not exhibit profound differences among conditions. Overall, the change of cycling grade alone from 0 to 8% did not induce a significant change in neuromuscular coordination. However, the postural change from seated to ST pedaling at 8% uphill grade was accompanied by increased and/or prolonged muscle activity of hip and knee extensors. The observed EMG activity patterns were discussed with respect to lower extremity joint moments. Monoarticular extensor muscles (GM, vastus lateralis) demonstrated greater modifications in activity patterns with the change in posture compared with their biarticular counterparts. Furthermore, muscle coordination among antagonist pairs of mono- and biarticular muscles was altered in the ST condition; this finding provides support for the notion that muscles within these antagonist pairs have different functions.

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.

scholarly journals The Relationship Between Additional Heads of the Quadriceps Femoris, the Vasti Muscles and the Patellar Ligament

2021 ◽  
Author(s):  
Łukasz Olewnik ◽  
Kacper Ruzik ◽  
Bartłomiej Szewczyk ◽  
Michał Podgórski ◽  
Paloma Aragonés ◽  
...  
Keyword(s):  
Vastus Lateralis ◽  
Rectus Femoris ◽  
Quadriceps Femoris ◽  
The Other ◽  
Lower Limbs ◽  
Patellar Ligament ◽  
Vastus Medialis ◽  
Vastus Intermedius ◽  
Deep Layers ◽  
The Relationship

Abstract Introduction: The quadriceps femoris consists of four muscles: the rectus femoris, vastus medialis, vastus intermedius and vastus lateralis. However, the effect of additional quadriceps femoris heads on the vasti muscles and patellar ligaments is unknown.Materials and Methods: One hundred and six lower limbs (34 male and 19 female cadavers) fixed in 10% formalin were examined.Results: On all lower extremities, the vastus lateralis consisted of superficial, intermediate and deep layers. The vastus medialis, on the other hand, consisted of only the longus and obliquus layers. Additional quadriceps femoris heads affected both the vasti muscles and the patellar ligaments.Conclusion: There is a strong correlation between the presence of accessory quadriceps femoris heads and effects on vasti muscles and patellar ligament.

scholarly journals Acute effect of partial body weight suspension on the level of cocontraction and gait biomechanics in women with knee osteoarthritis

2020 ◽  
Vol 33 ◽  
Author(s):  
Deborah Hebling Spinoso ◽  
Marcus Vinicius de Sobral Carvalho ◽  
Ana Carolina de Souza Trentin ◽  
Marcelo Tavella Navega
Keyword(s):  
Body Weight ◽  
Knee Osteoarthritis ◽  
Vastus Lateralis ◽  
Functional Limitation ◽  
Gluteus Maximus ◽  
Rectus Femoris ◽  
Treadmill Running ◽  
Significance Level ◽  
Significant Difference ◽  
Partial Body

Abstract Introduction: Knee osteoarthritis (OAK) is one of the most prevalent rheumatic diseases in the population, characterized by functional limitation and gait difficulties with profound clinical relevance, as walking is the most frequently performed daily activity. These functional limitations may be more pronounced when the disease is associated with obesity. Objective: To investigate the effect of different body weight suspension percentages on gait biomechanical variables and co-contraction percentages in women with OAK. Method: Fourteen women aged 50-75 years, with a body mass index between 26 and 35 and radiological diagnosis of OAK participated in the study. On the first day, anamnesis and familiarization with gait on the treadmill was performed. On the second day, treadmill gait assessment was performed using partial body weight support (SPPC) in three conditions-15%, 30%, and 45% suspension. During the evaluation, electromyographic and kinematic data were collected. The variables analyzed were percentage of hip (gluteus maximus/rectus femoris), knee (femoral biceps/vastus lateralis), and ankle (anterior tibial/lateral gastrocnemius), and length and step widths. A one-way analysis of variance was conducted, with a significance level of p < 0.05. Results: There was no significant difference in the length and step width and the level of co-contraction between the running conditions analyzed. Conclusion: Body weight suspension using SPPC during treadmill running did not alter the biomechanical variables of the gait of women with OAK.

EMG Activity of Six Muscles and VMO:VL Ratio Determination during a Maximal Squat Exercise

1995 ◽  
Vol 4 (3) ◽  
pp. 195-202 ◽  
Author(s):  
Peter A. Schaub ◽  
Teddy W. Worrell
Keyword(s):  
Lower Extremity ◽  
Vastus Lateralis ◽  
Gluteus Maximus ◽  
Rectus Femoris ◽  
Emg Activity ◽  
Kinetic Chain ◽  
Maximal Voluntary Isometric Contraction ◽  
Knee Rehabilitation ◽  
Intraclass Correlations ◽  
Ratio Determination

During knee rehabilitation, squats are a commonly used closed kinetic chain exercise. We have been unable to locate data reporting electromyographic (EMG) activity of lower extremity musculature during maximal effort squats and the contribution of gastrocnemius and gluteus maximus muscles. Therefore, the purposes of this study were (a) to quantify EMG activity of selected lower extremity muscles during a maximal isometric squat and during a maximal voluntary isometric contraction (MVIC), and (b) to determine ratios between the vastus medialis oblique (VMO) and vastus lateralis (VL) during maximal isometric squat and MVIC testing. Twenty-three subjects participated in a single testing session. Results are as follows: intraclass correlations for MVIC testing and squat testing ranged from .60 to .80 and .70 to .90, respectively. Percentage MVIC during the squat was as follows: rectus femoris 40 ± 30%, VMO 90 ± 70%, VL 70 ±40%, hamstrings 10 ± 10%, gluteus maximus 20 ± 10%, and gastrocnemius 30 ± 20%. No statistical difference existed in VMO:VL ratios during MVIC or squat testing. We conclude that large variations in muscle recruitment patterns occur between individuals during isometric squats.

Mono- and Biarticular Muscle Activity during Jumping in Different Directions

2003 ◽  
Vol 19 (3) ◽  
pp. 205-222 ◽  
Author(s):  
Stephanie L. Jones ◽  
Graham E. Caldwell
Keyword(s):  
Muscle Activity ◽  
Vastus Lateralis ◽  
Activity Patterns ◽  
Center Of Mass ◽  
Reaction Force ◽  
Gluteus Maximus ◽  
Rectus Femoris ◽  
Jump Condition ◽  
Activity Level ◽  
Biarticular Muscle

This study examined the role of mono- and biarticular muscles in control of countermovement jumps (CMJ) in different directions. It was hypothesized that monoarticular muscles would demonstrate the same activity regardless of jump direction, based on previous studies which suggest their role is to generate energy to maximize center-of-mass (CM) velocity. In contrast, biarticular activity patterns were expected to change to control the direction of the ground reaction force (GRF) and CM velocity vectors. Twelve participants performed maximal CMJs in four directions: vertical, forward, intermediate forward, and backward. Electromyographical data from 4 monoarticular and 3 biarticular lower extremity muscles were analyzed with respect to segmental kinematics and kinetics during the jumps. The biarticular rectus femoris (RF), hamstrings (HA), and gastrocnemius all exhibited changes in activity magnitude and pattern as a function of jump angle. In particular, HA and RF demonstrated reciprocal trends, with HA activity increasing as jump angle changed from backward to forward, while RF activity was reduced in the forward jump condition. The vastus lateralis and gluteus maximus both demonstrated changes in activity patterns, although the former was the only monoarticular muscle to change activity level with jump direction. Mono- and biarticular muscle activities therefore did not fit with their hypothesized roles. CM and segmental kinematics suggest that jump direction was initiated early in the countermovement, and that in each jump direction the propulsion phase began from a different position with unique angular and linear momentum. Issues that dictated the muscle activity patterns in each jump direction were the early initiation of appropriate forward momentum, the transition from countermovement to propulsion, the control of individual segment rotations, the control of GRF location and direction, and the influence of the subsequent landing.

Sign in / Sign up

Export Citation Format

Share Document