Activation of Antagonist Knee Muscles during Isokinetic Efforts in Prepubertal and Adult Males

2005 ◽  
Vol 17 (2) ◽  
pp. 171-181 ◽  
Author(s):  
Eleni Bassa ◽  
Dimitrios Patikas ◽  
Christos Kotzamanidis
Keyword(s):  
Muscle Activation ◽  
Vastus Lateralis ◽  
Force Production ◽  
Biceps Femoris ◽  
Antagonistic Activity ◽  
Adult Males ◽  
Significant Difference ◽  
Angular Velocities ◽  
Knee Muscle ◽  
Muscle Force Production

The deficit of muscle-force production observed in children can be partly attributed to neural factors, such as an increased level of coactivation. This hypothesis, however, has not been thoroughly investigated under concentric and eccentric isokinetic conditions at different angular velocities. Thus, the purpose of this study was to examine whether prepubescent children present higher levels of activation of the antagonist knee muscles during isokinetic, concentric, and eccentric knee efforts compared with adults. Eighteen prepubertal and 13 young adult males (age: 10.9 ± 0.5 and 18.1 ± 0.1 years, respectively) performed maximal concentric and eccentric knee extensions and flexions at 45, 90, and 180 degrees/s. The vastus lateralis and biceps femoris electromyogram was recorded and the antagonist activation (coactivation) was calculated. Concentric contractions for both groups revealed significantly higher coactivation values (p < .05) compared with the eccentric conditions. Furthermore, increasing the angular velocity increased the level of coactivation significantly only during the concentric efforts for both groups. No significant difference in the antagonistic activity of the vastus lateralis and biceps femoris, however, was found between groups. Therefore, increased antagonist knee-muscle activation, which enhances joint stabilization during isokinetic concentric and eccentric effort, is similar in both prepubescent and adult males.

Effects of Fatigue on Kinetic and Kinematic Variables During a 60-Second Repeated Jumps Test

2010 ◽  
Vol 5 (2) ◽  
pp. 218-229 ◽  
Author(s):  
Jeni R. McNeal ◽  
William A. Sands ◽  
Michael H. Stone
Keyword(s):  
Muscle Activation ◽  
Female Athletes ◽  
Vastus Lateralis ◽  
Force Production ◽  
Biceps Femoris ◽  
Peak Force ◽  
Ground Contact ◽  
And Gender ◽  
Anterior Tibialis ◽  
Initial Jump

Purpose:The aim of this study was to investigate the effects of a maximal repeated-jumps task on force production, muscle activation and kinematics, and to determine if changes in performance were dependent on gender.Methods:Eleven male and nine female athletes performed continuous countermovement jumps for 60 s on a force platform while muscle activation was assessed using surface electromyography. Performances were videotaped and digitized (60 Hz). Data were averaged across three jumps in 10-s intervals from the initial jump to the final 10 s of the test.Results:No interaction between time and gender was evident for any variable; therefore, all results represent data collapsed across gender. Preactivation magnitude decreased across time periods for anterior tibialis (AT, P < .001), gastrocnemius (GAS, P < .001) and biceps femoris (BF, P = .03), but not for vastus lateralis (VL, P = .16). Muscle activation during ground contact did not change across time for BF; however, VL, G, and AT showed significant reductions (all P < .001). Peak force was reduced at 40 s compared with the initial jumps, and continued to be reduced at 50 and 60 s (all P < .05). The time from peak force to takeoff was greater at 50 and 60 s compared with the initial jumps (P < .05). Both knee fexion and ankle dorsifexion were reduced across time (both P < .001), whereas no change in relative hip angle was evident (P = .10). Absolute angle of the trunk increased with time (P < .001), whereas the absolute angle of the shank decreased (P < .001).Conclusions:In response to the fatiguing task, subjects reduced muscle activation and force production and altered jumping technique; however, these changes were not dependent on gender.

scholarly journals Comparison of thigh muscle activations in single leg exercises: bench squat, step-up, airborne lunge

2021 ◽  
Vol 25 (6) ◽  
pp. 342-348
Author(s):  
Fahri S. Çinarli ◽  
Sena Çinarli ◽  
Emin Kafkas
Keyword(s):  
Muscle Activation ◽  
Vastus Lateralis ◽  
Biceps Femoris ◽  
Thigh Muscle ◽  
Knee Extensors ◽  
Energy Costs ◽  
Co Activation ◽  
Significant Difference ◽  
Muscle Activations ◽  
Sports Sciences

Background and Study Aim. Single leg exercises have some advantages in terms of time, practice and energy costs. However, the activation values that occur in different single leg exercises can be used for training planning. The aim of this research was to examine the thigh muscle activation values during three different single leg exercises. Materials and Methods. Ten healthy male volunteers who were students of the faculty of sports sciences participated in the study. In the study, the EMG ampilitude values of the vastus medialis (VM), vastus lateralis (VL), semitendinosus (SEM) and biceps femoris (BF) muscles were examined during Step-up, Bench Squat and Airborne Lunge exercises. At the same time, Quadriceps (VM+VL): Hamstring (SEM+BF) ratios were determined. Results. Significant differences were detected in all thigh muscles in the ascent and descent phases (p<0.05). While the greatest activation for the quadriceps group was seen in the airborne lunge, the greatest activation for the hamstring group was detected in the bench squat. A statistically significant difference was found in terms of exercise practices in the quadriceps: hamstring (Q:H) ratio (F(2,18)=12.282, p=.003). It was seen that the most balanced exercise was bench squat (Q:H=2.55), and the most unbalanced exercise (agonist dominant) was airborne lunge (Q:H=5.51). Conclusions. The findings show that the exercises examined can be selected depending on the purpose of the training. While bench squats can be preferred for more balanced co-activation the airborne lunge can be preferred for dominant knee extensors.

scholarly journals New insights on contraction efficiency in patients with Duchenne muscular dystrophy

2014 ◽  
Vol 117 (6) ◽  
pp. 658-662 ◽  
Author(s):  
Lilian Lacourpaille ◽  
François Hug ◽  
Arnaud Guével ◽  
Yann Péréon ◽  
Armelle Magot ◽  
...  
Keyword(s):  
Duchenne Muscular Dystrophy ◽  
Muscular Dystrophy ◽  
Muscle Activation ◽  
Time Lag ◽  
Force Production ◽  
Frame Rate ◽  
Force Transmission ◽  
Electromechanical Delay ◽  
Muscle Fascicle ◽  
Significant Difference

The decrease in muscle strength in patients with Duchenne muscular dystrophy (DMD) is mainly explained by a decrease in the number of active contractile elements. Nevertheless, it is possible that other electrochemical and force transmission processes may contribute. The present study aimed to quantify the effect of DMD on the relative contribution of electrochemical and force transmission components of the electromechanical delay (i.e., time lag between the onset of muscle activation and force production) in humans using very high frame rate ultrasound. Fourteen patients with DMD and thirteen control subjects underwent two electrically evoked contractions of the biceps brachii with the ultrasound probe over the muscle belly. The electromechanical delay was significantly longer in DMD patients compared with controls (18.5 ± 3.9 vs. 12.5 ± 1.4 ms, P < 0.0001). More precisely, DMD patients exhibited a longer delay between the onset of muscle fascicles motion and force production (13.6 ± 3.1 vs. 7.9 ± 2.0 ms, P < 0.0001). This delay was correlated to the chronological age of the DMD patients ( r = 0.66; P = 0.01), but not of the controls ( r = −0.45; P = 0.10). No significant difference was found for the delay between the onset of muscle stimulation and the onset of muscle fascicle motion. These results highlight the role of the alteration of muscle force transmission (delay between the onset of fascicle motion and force production) in the impairments of the contraction efficiency in patients with DMD.

scholarly journals Effects of Short-Term Training With Uncoupled Cranks in Trained Cyclists

2012 ◽  
Vol 7 (2) ◽  
pp. 113-120 ◽  
Author(s):  
Jack M. Burns ◽  
Jeremiah J. Peiffer ◽  
Chris R. Abbiss ◽  
Greig Watson ◽  
Angus Burnett ◽  
...  
Keyword(s):  
Muscle Activation ◽  
Vastus Lateralis ◽  
Biceps Femoris ◽  
Training Group ◽  
Recovery Phase ◽  
Muscle Recruitment ◽  
Short Term ◽  
Activation Patterns ◽  
Gross Efficiency ◽  
Muscle Activation Patterns

Purpose:Manufacturers of uncoupled cycling cranks claim that their use will increase economy of motion and gross efficiency. Purportedly, this occurs by altering the muscle-recruitment patterns contributing to the resistive forces occurring during the recovery phase of the pedal stroke. Uncoupled cranks use an independent-clutch design by which each leg cycles independently of the other (ie, the cranks are not fixed together). However, research examining the efficacy of training with uncoupled cranks is equivocal. The purpose of this study was to determine the effect of short-term training with uncoupled cranks on the performance-related variables economy of motion, gross efficiency, maximal oxygen uptake (VO2max), and muscle-activation patterns.Methods:Sixteen trained cyclists were matched-paired into either an uncoupled-crank or a normal-crank training group. Both groups performed 5 wk of training on their assigned cranks. Before and after training, participants completed a graded exercise test using normal cranks. Expired gases were collected to determine economy of motion, gross efficiency, and VO2max, while integrated electromyography (iEMG) was used to examine muscle-activation patterns of the vastus lateralis, biceps femoris, and gastrocnemius.Results:No significant changes between groups were observed for economy of motion, gross efficiency, VO2max, or iEMG in the uncoupled- or normal-crank group.Conclusions:Five weeks of training with uncoupled cycling cranks had no effect on economy of motion, gross efficiency, muscle recruitment, or VO2max compared with training on normal cranks.

scholarly journals Quadriceps and hamstrings coactivation in exercises used in prevention and rehabilitation of hamstring strain injury in young soccer players

2019 ◽  
Author(s):  
Gonzalo Torres ◽  
David Chorro ◽  
Archit Navandar ◽  
Javier Rueda ◽  
Luís Fernández ◽  
...  
Keyword(s):  
Muscle Activation ◽  
Vastus Lateralis ◽  
Rectus Femoris ◽  
Biceps Femoris ◽  
Activation Pattern ◽  
Male Youth ◽  
Maximum Voluntary Isometric Contraction ◽  
Hamstring Strain ◽  
Exercise Muscle ◽  
Injury Recovery

AbstractThis study aimed to study the co-activation of hamstring-quadriceps muscles during submaximal strength exercises without the use of maximum voluntary isometric contraction testing and compare (i) the inter-limb differences in muscle activation, (ii) the intra-muscular group activation pattern, and (iii) the activation during different phases of the exercise. Muscle activation was recorded by surface electromyography of 19 elite male youth players. Participants performed five repetitions of the Bulgarian squat, lunge and the squat with an external load of 10 kg. Electrical activity was recorded for the rectus femoris, vastus medialis, vastus lateralis, biceps femoris and semitendinosus. No significant inter-limb differences were found (F1, 13=619; p=0.82; partial η2=0.045). Significant differences were found in the muscle activation between different muscles within the muscle group (quadriceps and hamstrings) for each of the exercises: Bulgarian squat (F1,18=331: p<0.001; partial η2=0.80), lunge (F4,72=114.5; p<0.001; partial η2=0.86) and squat (F1,16=247.31; p<0.001; partial η2=0.93).Differences were found between the concentric, isometric and eccentric phases of each of the exercises (F2, 26=52.27; p=0.02; partial η2=0.80). The existence of an activation pattern of each of the muscles in the three proposed exercises could be used for muscle assessment and as a tool for injury recovery.

scholarly journals Electromyographic responses to Nordic curl and prone leg curl exercises in football players

2021 ◽  
Vol 25 (5) ◽  
pp. 288-298
Author(s):  
Murat Çilli ◽  
Merve N. Yasar ◽  
Onur Çakir
Keyword(s):  
Muscle Activity ◽  
Muscle Activation ◽  
Total Duration ◽  
Rectus Femoris ◽  
Random Order ◽  
Biceps Femoris ◽  
Activation Rate ◽  
Significant Difference ◽  
Activation Rates ◽  
Short Time

Background and Study Aim. The aim of this study is to examine the electromyographic responses to Nordic curl and prone leg curl exercises, having two different mechanics. Material and Methods. The athletes performed the prone leg curl and Nordic curl exercises in random order, 6 repetitions each. Electromyographic data of semimemranosus, semitendinosus, biceps femoris and rectus femoris muscles were recorded by 8-channel electromyography in order to examine the muscle responses to exercises. Total duration of exercise, cumulative integrated electromyographic values and muscle activation rates in 5 different intensity zones determined according to MVC% values have been compared. Results. Prone leg curl exercise occurred in less time than Nordic curl exercise. According to the cumulative integrated electromyography data results, all muscles showed similar muscle activation in both exercises. Comparing the muscle activation rates in the five intensity zones, more muscle activity was observed for Nordic curl exercise in the first intensity zone, while prone leg curl exercise was more active in the third and fourth zones. During the prone leg curl exercise, the muscle activation rate of the dominant leg is higher in the first intensity zone, whereas the non-dominant leg in the fourth intensity zone has a higher muscle activation. During the Nordic curl exercise, the muscle activation rates of the dominant leg in the first and fifth intensity zones are higher, whereas the nondominant leg in the fourth intensity zone is higher. Conclusions. Prone leg curl exercises can be preferred in order to stimulate high muscle activation in a short time. Comparing the two exercises there was no significant difference in muscle activity in dominant and nondominant legs.

scholarly journals Static Loading of the Knee Joint Results in Modified Single Leg Landing Biomechanics

2019 ◽  
Author(s):  
Michael W. Olson
Keyword(s):  
Knee Joint ◽  
Static Loading ◽  
Vastus Lateralis ◽  
Rectus Femoris ◽  
Biceps Femoris ◽  
Rate Of Force Development ◽  
External Loading ◽  
Force Development ◽  
Before And After ◽  
Angular Velocities

ABSTRACTBackgroundExternal loading of the ligamentous tissues induces mechanical creep, which modifies neuromuscular response to perturbations. It is not well understood how ligamentous creep affects athletic performance and contributes to modifications of knee biomechanics during functional tasks.Hypothesis/PurposeThe purpose of this study was to examine the mechanical and neuromuscular responses to single leg drop landing perturbations before and after passive loading of the knee joint.Study DesignDescriptive laboratory studyMethodsMale (n=7) and female (n=14) participants’ (21.3 ± 2.1 yrs, 1.69 ± 0.09 m, 69.3 ± 13.0 kg) right hip, knee, and ankle kinematics were assessed during drop landings performed from a 30 cm height onto a force platform before and after a 10 min creep protocol. Electromyography (EMG) signals were recorded from rectus femoris (RF), vastus lateralis (VL), vastus medialis (VM), semimembranosus (SM), and biceps femoris (BF) muscles. The creep protocol involved fixing the knee joint at 35° during static loading with perpendicular loads of either 200 N (males) or 150 N (females). Maximum, minimum, range of motion (ROM), and angular velocities were assessed for the hip, knee, and ankle joints, while normalized average EMG (NAEMG), average vertical ground reaction forces (aVGRF), and rate of force development (RFD) were assessed at landing. Rate of force development (RFD) was calculated during the landings using ANOVAs. Alpha was set at 0.05.ResultsMaximum hip flexion velocity decreased (p < 0.01). Minimum knee flexion velocity increased (p < 0.02). Minimum knee ad/abduction velocity decreased (p < 0.001). Ankle ROM decreased (p < 0.001). aVGRF decreased (p < 0.02). RFD had a non-significant trend (p = 0.076). NAEMG was significant between muscle groups (p < 0.02).ConclusionDistinct changes in velocity parameters are attributed to the altered mechanical behavior of the knee joint tissues and may contribute to changes in the loading of the leg during landing.

scholarly journals TRAINING LOAD DEMANDS MEASURED BY SURFACE ELECTROMYOGRAPHY WEARABLE TECHNOLOGY WHEN PERFORMING LAW ENFORCEMENT-SPECIFIC BODY DRAGS

2020 ◽  
pp. 001
Author(s):  
Robert George Lockie ◽  
Ashley Bloodgood ◽  
Matthew Moreno ◽  
Megan McGuire ◽  
Katherine Balfany ◽  
...  
Keyword(s):  
Law Enforcement ◽  
Surface Electromyography ◽  
Muscle Activation ◽  
Vastus Lateralis ◽  
Gluteus Maximus ◽  
Biceps Femoris ◽  
Wearable Technology ◽  
Training Load ◽  
Semg Signal ◽  
Body Drag

The use of surface electromyography (sEMG) wearable technology to measure training load (TL) during law enforcement-specific tasks (e.g. a body drag) requires investigation. This study determined muscle activation differences represented as TL during a 9.75-m drag with 74.84 kg and 90.72 kg dummies. Eight men and three women were fitted with a compression short or legging embedded with sEMG wearable technology to measure the quadriceps (QUAD; vastus medialis+vastus lateralis), biceps femoris (BF), and gluteus maximus (GM). After fitting on day one, participants completed maximal voluntary isometric contractions for each muscle to normalize the sEMG signal and calculate TL units. On days two and three, participants performed a 9.75 m body drag using either the 74.84 kg or the 90.72 kg dummy while wearing the technology. Participants lifted the dummy off the floor to a standing position and dragged it as quickly as possible over 9.75 m. Paired samples t-tests calculated between-drag differences for: time; QUAD, BF, GM, and total TL; and QUAD-BF, GM-BF, anterior-posterior (QUAD-GM+BF) ratios. QUAD TL was 9% greater (p=0.035), and GM TL was 8% lower (p=0.043), in the 90.72 kg body drag compared to the 74.84 kg drag. There were no between-mass differences in time, BF TL, total TL, or the ratios. QUAD TL increased while GM TL decreased when participants dragged a 90.72 kg dummy. As drag time was not different between the masses, drag mechanics may have changed leading to increased QUAD TL. sEMG wearable technology could be a useful method to measure TL in law enforcement-specific dragging tasks.

scholarly journals Evaluation of the Lower Limb Muscles’ Electromyographic Activity during the Leg Press Exercise and Its Variants: A Systematic Review

2020 ◽  
Vol 17 (13) ◽  
pp. 4626
Author(s):  
Isabel Martín-Fuentes ◽  
José M. Oliva-Lozano ◽  
José M. Muyor
Keyword(s):  
Muscle Activation ◽  
Vastus Lateralis ◽  
Muscular Activity ◽  
Rectus Femoris ◽  
Biceps Femoris ◽  
Quadriceps Muscle ◽  
Electromyographic Activity ◽  
Full Extension ◽  
Cross Sectional ◽  
Leg Press

The aim of this study was to analyze the literature on muscle activation measured by surface electromyography (sEMG) of the muscles recruited when performing the leg press exercise and its variants. The Preferred Reporting Items of Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed to report this review. The search was carried out using the PubMed, Scopus, and Web of Science electronic databases. The articles selected met the following inclusion criteria: (a) a cross-sectional or longitudinal study design; (b) neuromuscular activation assessed during the leg press exercise, or its variants; (c) muscle activation data collected using sEMG; and (d) study samples comprising healthy and trained participants. The main findings indicate that the leg press exercise elicited the greatest sEMG activity from the quadriceps muscle complex, which was shown to be greater as the knee flexion angle increased. In conclusion, (1) the vastus lateralis and vastus medialis elicited the greatest muscle activation during the leg press exercise, followed closely by the rectus femoris; (2) the biceps femoris and the gastrocnemius medialis showed greater muscular activity as the knee reached full extension, whereas the vastus lateralis and medialis, the rectus femoris, and the tibialis anterior showed a decreasing muscular activity pattern as the knee reached full extension; (3) evidence on the influence of kinematics modifications over sEMG during leg press variants is still not compelling as very few studies match their findings.

Altering muscle activity in the lower extremities by bipedal landing with different drop tasks and shoes

2021 ◽  
pp. 1-11
Author(s):  
Yang Yang ◽  
Changxiao Yu ◽  
Chenhao Yang ◽  
Liqin Deng ◽  
Weijie Fu
Keyword(s):  
Lower Extremity ◽  
Muscle Activation ◽  
Vastus Lateralis ◽  
Movement Control ◽  
Rectus Femoris ◽  
Biceps Femoris ◽  
The Body ◽  
Basketball Players ◽  
Lower Extremity Muscle ◽  
Body Tissues

BACKGROUND: The ability of the lower-extremity muscle activation directly affects the performance and in turn interacts with the loading conditions of the muscle itself. However, systematic information concerning the characteristics of lower-extremity muscle during landings is lacking. In particular, the landing height and shoes are also important factors based on the actual situation, which could further contribute to understanding the neuromuscular activity and how biochemical response of the body tissues to double-leg drop landings. OBJECTIVE: The study was to investigate the effects of landing tasks on the activation of lower-extremity muscles and explore the relationship among movement control, landing heights, shoe cushioning, and muscle activities. METHODS: Twelve male basketball players were recruited to perform drop jump (DJ) and passive landing (PL) from three heights (30, 45, and 60 cm) while wearing highly-cushioned basketball shoes (HC) and less-cushioned control shoes (LC). EMG electrodes were used to record the activities of the target muscles (rectus femoris, vastus lateralis, biceps femoris, tibialis anterior, and lateral gastrocnemius) during the landing tasks. RESULTS: Pre- and post-activation activity of the lower-extremity muscles significantly decreased during PL compared with those during DJ (p< 0.05). No significant shoe effects on the characteristics of muscle activation and coactivation during DJ movements were observed. However, the participants wearing LC showed significantly higher muscle post-activation (p< 0.05) at the three drop heights during PL compared with those wearing HC. Coactivation of the ankle muscles was higher in LC than in HC during 30-cm PL (p< 0.05). CONCLUSIONS: The activation patterns of lower-extremity muscles can be significantly influenced by landing types. Highly-cushioned basketball shoes would help reduce the risk of injuries by appropriately tuning the muscles during the PL.

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