scholarly journals Co-contraction training: myoelectric activity and recruitment strategies in an unorthodox resistance training technique.

2021 ◽  
Author(s):  
Nilson Ribeiro dos Santos Silva ◽  
Matheus Pacheco ◽  
Rafael Akira Fujita ◽  
Marina Mello Villalba ◽  
MATHEUS MACHADO GOMES
Keyword(s):  
Vastus Lateralis ◽  
Rectus Femoris ◽  
Biceps Femoris ◽  
Voluntary Contraction ◽  
Lower Limbs ◽  
Emg Activity ◽  
Myoelectric Activity ◽  
Muscle Recruitment ◽  
Recruitment Pattern ◽  
Recruitment Patterns

Objective To elucidate the muscle recruitment patterns and interindividual variability during co-contraction training sessions for lower limbs. Methods Ten active male young adults underwent two days of tests, in which they performed, for each leg, a maximal isometric voluntary contraction protocol followed by a co-contraction training set. We acquired myoelectric (EMG) activity from the sartorius, biceps femoris long and short heads, semitendinosus, semimembranosus, rectus femoris, vastus lateralis and vastus medialis and tensor facia latae during both protocols. We used iterative HLM analyses and bootstrap ANOVAs to explain within and between participant variances. Results On average, participants started recruiting 36% of their maximum EMG amplitude, showing decays of 0.41% per repetition and increasing 7.45% from day 1 to day 2. Participants who started with higher recruitment showed greater decays over repetitions and vice-versa. The training stimulated similarly the ratio of participants’ flexors and extensors. However, participants demonstrated different average muscle recruitment patterns with some individuals modifying, largely, their recruitment over repetitions/days. Between and within-variability in recruitment pattern was maintained throughout repetitions and days. We found no consistent similarity in terms of pairs of participants as to find common types of recruitment. Conclusion Co-contraction training seems to be effective to recruit thigh muscles of both legs along an entire set of repetitions and days. Despite the accounted variations in intramuscular recruitment, co-contraction training evokes similar muscular in flexor’s and extensor’s recruitment among participants.

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.

scholarly journals Functional assessment of muscle response in lower limbs of tumbling gymnasts through tensiomyography

2016 ◽  
Vol 64 (3) ◽  
pp. 505
Author(s):  
Nicolás Rojas-Barrionuevo ◽  
Mercedes Vernetta-Santana ◽  
Jesús López-Bedoya
Keyword(s):  
Delay Time ◽  
High Performance ◽  
Vastus Lateralis ◽  
Rectus Femoris ◽  
Response Speed ◽  
Biceps Femoris ◽  
Lower Limbs ◽  
Muscle Response ◽  
Antagonist Muscles ◽  
Before And After

Introduction: Jumping capacity, a distinctive technical skill of tumbling gymnasts, is associated to a successful performance in training and competition; hence the need for an individualized, precise and localized assessment of the most demanded muscle structures.Objective: To assess muscle response of the flexo-extension structure in the knee joint and the extension of the ankle joint in a sample of 12 high-performance male gymnasts.Materials and methods: An acrobatic training protocol including sets of forward somersault in tumbling track was conducted. The contraction time, delay time and deformation of muscle belly were evaluated, and the muscular response speed was calculated using tensiomyography before and after the training intervention in different periods of time.Results: Significant differences were found (p<0.05) according to the muscle group involved, where rectus femoris and biceps femoris presented greater enhancement and shortening of the contraction and delay time. Major differences appeared between agonist-antagonist muscles (vastus lateralis-biceps femoris) (p<0.05) due to a decrease in the contraction and delay speed in vastus medialis (p<0.001).Conclusions: Tensiomyography allows estimating the states of activation-enhancing of the musculature responsible of jumping in tumblers, as well as planning the training based on the state of muscle fatigue.

scholarly journals Electromyographic evaluation of the lower limbs of patients with Down syndrome in hippotherapy

2017 ◽  
Vol 39 (1) ◽  
pp. 17 ◽  
Author(s):  
Mariane Fernandes Ribeiro ◽  
Ana Paula Espindula ◽  
Alex Abadio Ferreira ◽  
Luciane Aparecida Pascucci Sande de Souza ◽  
Vicente De Paula Antunes Teixeira
Keyword(s):  
Down Syndrome ◽  
Muscle Activation ◽  
Motor Behavior ◽  
Vastus Lateralis ◽  
Rectus Femoris ◽  
Gluteus Medius ◽  
Biceps Femoris ◽  
Functional Results ◽  
Lower Limbs ◽  
Tensor Fasciae Latae

Hippotherapy is a therapeutic method that uses the horse’s movement to achieve functional results in practitioners with Down syndrome (DS), who present motor and neurophysiological changes that affect the musculoskeletal system. Evaluating the motor behavior related to the control and the improvement of muscle activation in practitioners with Down syndrome subjected to hippotherapy. 10 practitioners were divided into two groups: Down Group (DG) – practitioners with DS, and Healthy Group (HG) – practitioners with no physical impairment. The muscles gluteus medius, tensor fasciae latae, rectus femoris, vastus medialis, vastus lateralis, biceps femoris, tibialis anterior and gastrocnemius were evaluated by electromyography using gross RMS values, which correspond to muscle activation; the evaluations were performed on the 1st and 10th hippotherapy sessions (frequency: once a week), and after 2 months interval without treatment, they were performed on the 1st and 10th hippotherapy sessions (frequency: twice a week). It was noted that activation of the studied muscles increased with the passing of sessions, regardless the weekly frequency of attendance; however, the period without treatment resulted in reduction of this effect. Practitioners with DS presented satisfactory changes in muscle activation pattern, in learning and in motor behavior during hippotherapy sessions. 

Behavior of coactive muscles during fatigue

1993 ◽  
Vol 74 (1) ◽  
pp. 170-175 ◽  
Author(s):  
J. A. Psek ◽  
E. Cafarelli
Keyword(s):  
Time Course ◽  
Vastus Lateralis ◽  
Biceps Femoris ◽  
Close Correlation ◽  
Voluntary Contraction ◽  
Knee Extensors ◽  
Emg Activity ◽  
Short Period ◽  
Force Time ◽  
Knee Flexors

Coactivation is antagonist muscle activity that occurs during voluntary contraction. Recently, we showed that the extent of coactivity in the knee flexors decreases after a short period of resistance training of the knee extensors (8). The purpose of the present experiment was to study the time course of coactivation in the knee flexors during fatigue of the knee extensors. Ten male subjects performed repeated submaximal static leg extensions in a low-intensity long-duration and a high-intensity short-duration fatigue protocol until they could no longer produce the required force [time limit of endurance (Tlim)]. Maximal voluntary contraction (MVC), submaximal force, and surface electromyographic (EMG) activity were measured periodically. Vastus lateralis EMG increased progressively during fatigue of the extensor muscles (P < 0.05), resulting in a 38% change from control at Tlim. Biceps femoris EMG, which was our measure of coactivation, also increased by approximately 60% at Tlim in each protocol (P < 0.05). These observations lead us to conclude that a small but significant force loss during repeated static contractions to Tlim is due to an increase in antagonist activity. Moreover, the close correlation between the antagonist and agonist EMG supports the notion of a "common drive" to both motoneuron pools (10).

scholarly journals Kinesiological Analysis of Stationary Running Performed in Aquatic and Dry Land Environments

2015 ◽  
Vol 49 (1) ◽  
pp. 5-14 ◽  
Author(s):  
Cristine Lima Alberton ◽  
Stephanie Santana Pinto ◽  
Natália Amélia da Silva Azenha ◽  
Eduardo Lusa Cadore ◽  
Marcus Peikriszwili Tartaruga ◽  
...  
Keyword(s):  
Aquatic Environment ◽  
Vastus Lateralis ◽  
Rectus Femoris ◽  
Biceps Femoris ◽  
Distinct Pattern ◽  
Lower Limbs ◽  
Maximal Velocity ◽  
Dry Land ◽  
Emg Signal ◽  
Neuromuscular Responses

Abstract The purpose of the present study was to analyze the electromyographic (EMG) signals of the rectus femoris (RF), vastus lateralis (VL), semitendinosus (ST) and short head of the biceps femoris (BF) during the performance of stationary running at different intensities in aquatic and dry land environments. The sample consisted of 12 female volunteers who performed the stationary running exercise in aquatic and dry land environments at a submaximal cadence (80 beats·min-1 controlled by a metronome) and at maximal velocity, with EMG signal measurements from the RF, VL, ST and BF muscles. The results showed a distinct pattern between environments for each muscle examined. For the submaximal cadence of 80 beats·min-1, there was a reduced magnitude of the EMG signal in the aquatic environment, except for the ST muscle, the pattern of which was similar in both environments. In contrast to the submaximal cadence, the pattern of the EMG signal from all of the muscles showed similar magnitudes for both environments and phases of movement at maximal velocity, except for the VL muscle. Therefore, the EMG signals from the RF, VL, ST and BF muscles of women during stationary running had different patterns of activation over the range of motion between aquatic and dry land environments for different intensities. Moreover, the neuromuscular responses of the lower limbs were optimized by an increase in intensity from submaximal cadence to maximal velocity.

scholarly journals The Effect of Static Stretching on Maximal Voluntary Contraction and Force-Time Curve Characteristics

2006 ◽  
Vol 15 (3) ◽  
pp. 185-194 ◽  
Author(s):  
Christos Papadopoulos ◽  
Vasilios I. Kalapotharakos ◽  
Georgios Noussios ◽  
Konstantinos Meliggas ◽  
Evangelia Gantiraga
Keyword(s):  
Maximal Voluntary Contraction ◽  
Isometric Force ◽  
Rectus Femoris ◽  
Biceps Femoris ◽  
Voluntary Contraction ◽  
Emg Activity ◽  
Static Stretching ◽  
Time Curve ◽  
Significant Difference ◽  
Force Time

Objective:To examine the effect of static stretching on maximal voluntary contraction (MVC) and isometric force-time curve characteristics of leg extensor muscles and EMG activity of rectus femoris (RF), biceps femoris (BF), and gastrocnemius (GA).Design:A within subjects experimental design.Participants:Ten healthy students were tested after a jogging and a jogging/stretch protocol.Intervention:The stretching protocol involved a 10 min jog and seven static stretching exercises.Main Outcomes:Measurements included MVC, time achieved to MVC (TMVC), force at 100ms (F100), index of relative force (IRF), index of rate of force development (IRFD), and average integrated EMG activity (AEMG).Results:There were slight but no significant changes in MVC (1%), TMVC(4.8%), F100(7.8%), IRF (1%), and IRFD(3.5%) between measurement. A significant difference (21%;P< 0.05) in AEMG of RF was found.Conclusions:The present study indicated that a moderate volume of static stretching did not alter significantly the MVC and the isometric force-time curve characteristics. Neural inhibition, as it is reflected from AEMG of RF, did not alter MVC and isometric force-time curve characteristics.

Lunges activate the gluteus maximus muscles more than back squats when both exercises are standardized

2021 ◽  
pp. 1-7
Author(s):  
Rodrigo Ramalho Aniceto ◽  
André Luiz Torres Pirauá ◽  
Leonardo da Silva Leandro ◽  
Hélen Cristina Ferreira da Silva ◽  
Diego Mesquita Silva ◽  
...  
Keyword(s):  
Resistance Training ◽  
Vastus Lateralis ◽  
Knee Extensor ◽  
Gluteus Maximus ◽  
Biceps Femoris ◽  
Lower Limbs ◽  
Emg Activity ◽  
Flexor Muscle ◽  
Back Squat ◽  
Trunk Inclination

BACKGROUND: Squats are considered one of the main exercises for the lower limbs and are used in resistance training under different contexts, including rehabilitation and sports performance. OBJECTIVE: To compare the EMG activity of different muscles in back squat and lunge exercises in trained women. METHODS: Ten healthy women experienced in resistance training performed back squat and lunge exercises on a Smith machine (total work: 70% of 1RM, 1 set, 10 repetitions and 2-s/2-s of execution speed) with an interval of 20-min between exercises. Both exercises were standardized in relation to the trunk inclination and were performed with an erect trunk parallel to the cursor of the guided bar. RESULTS: The EMG activity of the vastus medialis (VM), vastus lateralis (VL), biceps femoris (BF), and gluteus maximus (GM) were analyzed. There were no significant differences in the EMG activity of the VM, VL, and BF muscles between the back squat and lunge exercises (P> 0.05); however, GM activation was greater during the lunge exercise (effect size = 1.15; P= 0.001). CONCLUSIONS: Lunges were more effective in recruiting the GM when compared to back squats. However, both exercises can be recommended when the goal is knee extensor and flexor muscle activity.

scholarly journals Modificación de patrones cinemáticos y electromiográficos en extremidad inferior por el uso de celular (Modification of kinematic and electromyographic patterns in the lower limb by the use of cell phones)

Retos ◽  
2020 ◽  
pp. 354-358
Author(s):  
Oscar David Valencia Cayupán ◽  
María José Hudson ◽  
Felipe Carpes ◽  
Marcos Kunzler ◽  
Fernanda Gándara ◽  
...  
Keyword(s):  
Lower Limb ◽  
Cell Phone ◽  
Sagittal Plane ◽  
Biomechanical Model ◽  
Rectus Femoris ◽  
Biceps Femoris ◽  
Lower Limbs ◽  
Emg Activity ◽  
Protective Strategy ◽  
Hip Flexion

Las lesiones de transeúntes relacionadas al uso de teléfono celular han aumentado en relación con el total de accidentes peatonales. El objetivo de este estudio fue comparar variables cinemáticas y electromiográficas de ambas extremidades inferiores al enfrentar un obstáculo, con (CC) y sin (SC) el uso de celular. Diez mujeres jóvenes fueron evaluadas, las cuales caminaron y enfrentaron un obstáculo CC y SC. Con un modelo biomecánico 3D se evaluó la cinemática de extremidad inferior (plano sagital de cadera, rodilla, tobillo, junto al “toe clearance”). Al mismo tiempo se registró la actividad electromiográfica (EMG) de los siguientes músculos: tibial anterior (TA), gastrocnemio medial (GM), recto anterior (RA) y bíceps femoral (BF). Se calculó la amplitud EMG promedio de cada músculo, y el porcentaje de coactivación muscular entre: TA-GM y RA-BF. Se analizó la estrategia de ambas piernas, considerando un primer (P1) y segundo paso (P2) al cruzar el obstáculo, comparando entre una marcha CC vs CS. Según los resultados, la marcha CC incrementa el toe clearance, flexión de cadera, y la amplitud del GM, observado tanto en P1 como P2 al cruzar el obstáculo. Adicionalmente, el P2 reveló un incremento en la flexión de rodilla y tobillo. Por otro lado, la amplitud del TA y coactivación muscular entre TA-GM también aumentó CC en el P2. En conclusión, las variables cinemáticas y electromiográficas en las extremidades inferiores se modifican al cruzar un obstáculo CC. Estos hallazgos podrían indicar una estrategia protectora durante la tarea dual evaluada, minimizar el riesgo de caída. Abstract. Pedestrian injuries related to the use of cell phone have increased in relation to the total number of pedestrian accidents. The aim of this study was to compare kinematic and electromyographic variables in both lower limbs at facing an obstacle, with (WC) and without (WoC) the use of a cell phone. Ten young women were evaluated, while walking and facing an obstacle WC and WoC. A 3D biomechanical model was used to evaluate the lower limb kinematics (hip, knee, ankle in the sagittal plane, together with “toe clearance”). At the same time, the electromyographic (EMG) activity was registered in the following muscles: tibialis anterior (TA), gastrocnemius medialis (GM), rectus femoris (RF) and biceps femoris (BF). The mean EMG amplitude of each muscle and the muscular coactivation percentage between: TA-GM and RA-BF were calculated. The strategy for both lower limbs considering the first (P1) and the second step (P2) were analyzed when crossing the obstacle, comparing between gait WC vs WoC. According to results, the gait WC increase the toe clearance, hip flexion, and the GM amplitude, observed both in P1 as P2 when the person crossed the obstacle. Furthermore, the P2 revealed an increase in the knee and ankle flexion. On the other hand, the TA amplitude and the muscular coactivation between TA-GM also increased WC in the P2. In conclusion, the kinematic and electromyographic variables in the lower limbs are modified when crossing an obstacle WC. These findings could indicate a protective strategy during the dual-task evaluated, minimizing the risk of falling.

Lower Limb EMG Activity during Selected Stepping Exercises

1998 ◽  
Vol 7 (2) ◽  
pp. 102-111 ◽  
Author(s):  
Gilbert M. Willett ◽  
Gregory M. Karst ◽  
Ellen M. Canney ◽  
Derrick Gallant ◽  
Jodene M. Wees
Keyword(s):  
Lower Limb ◽  
Vastus Lateralis ◽  
Biceps Femoris ◽  
Lower Limbs ◽  
Emg Activity ◽  
Muscle Strengthening ◽  
Lower Limb Muscles ◽  
Amplitude Data ◽  
Knee Muscle ◽  
The Right

The purpose of this study was to investigate the electromyographic (EMG) activity of selected lower limb muscles during forward- and backward-facing stair-stepping exercises using a hydraulic step ergometer and during step aerobics using a standard 8 in. high step. Surface electrodes recorded EMG data from the vastus lateralis (VL), vastus medialis obliquus (VMO), and biceps femoris (BF) muscles on the right lower limbs of 13 healthy subjects under each of the four exercise conditions. Normalized mean EMG amplitude data were used to test for activity-dependent differences. Results indicated that (a) the VL and VMO were significantly (p < .05) more active during step ergometry than during step aerobics, (b) the BF was significantly (p < .05) more active during step aerobics than during step ergometry, and (c) when forward- versus backward-facing positions were compared, there were no statistically significant differences in mean EMG activity for either of the activities. These findings provide information relevant to the use and progression of stepping exercises commonly used for knee muscle strengthening and knee injury rehabilitation programs.

scholarly journals Electrical Stimulation Frequency and Skeletal Muscle Characteristics: Effects on Force and Fatigue

2017 ◽  
Vol 27 (4) ◽  
Author(s):  
Maria Vromans ◽  
Pouran Faghri
Keyword(s):  
Electrical Stimulation ◽  
Vastus Lateralis ◽  
Voluntary Contraction ◽  
Current Intensity ◽  
Muscle Size ◽  
Emg Activity ◽  
Abductor Pollicis Brevis ◽  
Fiber Composition ◽  
Initial Drop ◽  
Initial Force

This investigation aimed to determine the force and muscle surface electromyography (EMG) responses to different frequencies of electrical stimulation (ES) in two groups of muscles with different size and fiber composition (fast- and slow-twitch fiber proportions) during a fatigue-inducing protocol. Progression towards fatigue was evaluated in the abductor pollicis brevis (APB) and vastus lateralis (VL) when activated by ES at three frequencies (10, 35, and 50Hz). Ten healthy adults (mean age: 23.2 ± 3.0 years) were recruited; participants signed an IRB approved consent form prior to participation. Protocols were developed to 1) identify initial ES current intensity required to generate the 25% maximal voluntary contraction (MVC) at each ES frequency and 2) evaluate changes in force and EMG activity during ES-induced contraction at each frequency while progressing towards fatigue. For both muscles, stimulation at 10Hz required higher current intensity of ES to generate the initial force. There was a significant decline in force in response to ES-induced fatigue for all frequencies and for both muscles (p<0.05). However, the EMG response was not consistent between muscles. During the progression towards fatigue, the APB displayed an initial drop in force followed by an increase in EMG activity and the VL displayed a decrease in EMG activity for all frequencies. Overall, it appeared that there were some significant interactions between muscle size and fiber composition during progression towards fatigue for different ES frequencies. It could be postulated that muscle characteristics (size and fiber composition) should be considered when evaluating progression towards fatigue as EMG and force responses are not consistent between muscles.

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