Elbow Flexor Inhibition as a Function of Muscle Length

2002 ◽  
Vol 18 (1) ◽  
pp. 46-56 ◽  
Author(s):  
Luciana Brondino ◽  
Esther Suter ◽  
Hae-Dong Lee ◽  
Walter Herzog
Keyword(s):  
Isometric Force ◽  
Knee Extensor ◽  
Elbow Flexor ◽  
Peak Force ◽  
Knee Extensors ◽  
Emg Activity ◽  
Elbow Flexors ◽  
Muscle Inhibition ◽  
Voluntary Contractions ◽  
Maximal Isometric Force

Muscle inhibition (MI) in human knee extensors increases with increasing maximal voluntary force as a function of knee angle. It was speculated that this angle-dependent MI was modulated by force-dependent feedback, likely Golgi tendon organ pathways. Such angle-dependent MI is of clinical and theoretical importance. The purpose of this study was to determine MI in human elbow flexors for maximal voluntary contractions. Muscle inhibition, elbow flexor force, and electromyographic (EMG) activity were measured in 31 volunteers at elbow angles between 30º and 120º. MI and elbow flexor EMG were the same at all elbow angles. Maximal isometric forces were greatest at the 70º angle, and never fell below 70% of the peak force at any of the tested angles. From these results it is concluded that force-dependent modulation of MI did not occur in the elbow flexors, possibly because maximal isometric force remained relatively close (within 30%) to the peak force. In contrast, force-dependent modulation of MI occurred in the knee extensors at the most extended angles, when the average knee extensor force had dropped to 50% or less of the maximal knee extensor force. It is likely that human maximal voluntary contractions are not associated with a given activation. Rather, activation appears to be modulated by force-dependent feedback at force levels below 70% of the absolute peak force, which manifests itself in a change of MI that parallels the level of maximal isometric force in voluntary contractions.

scholarly journals Spinal contribution to neuromuscular recovery differs between elbow-flexor and knee-extensor muscles after a maximal sustained fatiguing task

2020 ◽  
Vol 124 (3) ◽  
pp. 763-773 ◽  
Author(s):  
Gianluca Vernillo ◽  
John Temesi ◽  
Matthieu Martin ◽  
Renata L. Krüger ◽  
Guillaume Y. Millet
Keyword(s):  
Knee Extensor ◽  
Elbow Flexor ◽  
Knee Extensors ◽  
Elbow Flexors ◽  
Recovery Pattern ◽  
Motoneuron Excitability ◽  
Neural Processes ◽  
Extensor Muscles ◽  
Voluntary Contractions ◽  
Knee Extensor Muscles

By comparing the changes in motoneuron excitability in elbow-flexor and knee-extensor muscles after sustained fatiguing maximal voluntary contractions, this study shows that motoneuron recovery behavior depends on the muscle performing the exercise. A different recovery pattern in motoneuron excitability occurs in elbow flexors as it recovered by 60 s whereas knee extensors were unaffected by fatigue. This finding can help to increase understanding of the effect of a fatigue and subsequent recovery on neural processes.

scholarly journals Effects of submaximal cycling at different exercise intensities on maximal isometric force output of the non-exercised elbow flexor muscles

2018 ◽  
Vol 105 (2) ◽  
pp. 177-187
Author(s):  
R Matsuura ◽  
K Hirakoba ◽  
K Takahashi
Keyword(s):  
Isometric Force ◽  
Lactate Concentration ◽  
Elbow Flexor ◽  
Emg Activity ◽  
Force Output ◽  
Cardiorespiratory Responses ◽  
Flexor Muscles ◽  
Elbow Flexor Muscles ◽  
The Right ◽  
Maximal Isometric Force

The purpose of this study was to examine the effects of submaximal cycling at different exercise intensities on maximal isometric force output of the non-exercised elbow flexor muscles after the cycling. A total of 8 healthy young men performed multiple maximal voluntary contractions by the right elbow flexion before, immediately after, 5 min after, and 10 min after a 6-min submaximal cycling at ventilatory threshold (LI), 70% (MI), and 80% (HI) with both arms relaxed in the air. Force and surface electromyogram (EMG) of the right biceps brachii muscle during the multiple MVCs, blood lactate concentration ([La]), cardiorespiratory responses, and sensations of fatigue for legs (SEF-L) were measured before, immediately after, 5 min after, and 10 min after the submaximal cycling with the three different exercise intensities. Immediately after the submaximal cycling, [La], cardiorespiratory responses, and SEF-L were enhanced in proportion to an increase in exercise intensity of the cycling. Changes in force and EMG activity during the multiple MVCs were not significantly different across the three conditions. The findings imply that group III/IV muscle afferent feedback after the submaximal cycling does not determine the magnitude of MVC force loss of the non-exercised upper limb muscles.

scholarly journals Force and Electromyographic Responses of the Biceps Brachii after Eccentric Exercise in Athletes and non-Athletes

2019 ◽  
Vol 68 (1) ◽  
pp. 203-210 ◽  
Author(s):  
Adam Kawczyński
Keyword(s):  
Eccentric Exercise ◽  
Elbow Joint ◽  
Joint Angle ◽  
Biceps Brachii ◽  
Isometric Force ◽  
Emg Activity ◽  
Elbow Flexors ◽  
Force Response ◽  
Baseline Values ◽  
Maximal Isometric Force

Abstract The aim of this study was to compare skeletal muscle response to elbow flexors eccentric exercise in athletes and non-athletes. A set of eccentric (ECC) exercises was performed in a group of 12 athletes and 12 non-athlete controls. Maximal isometric force, electromyographic (EMG) activity of the biceps brachii and the resting elbow angle were assessed before, immediately, 48 hours, 5 and 10 days after high-intensity ECC exercises. During the set of the ECC exercises each participant performed 25 eccentric contractions of elbow flexors. Each contraction consisted of lowering a dumbbell from the flexed (elbow joint angle: $\left. 5{{0}^{\underline{{}^\circ }}} \right)$ to the extended elbow (elbow joint angle: $\left. 18{{0}^{\underline{{}^\circ }}} \right)$ position. The weight of the dumbbell was set at 80% of one-repetition maximum (1RM). The ECC contractions caused a decrease in maximal isometric force in both groups. The variable dropped by 8% in non-athletes and by 24% in athletes. Furthermore, the EMG RMS increased significantly only for non-athletes 10 days after the ECC exercise compared to baseline values. The present study showed different effects of ECC exercise on force and EMG in athletes and non-athletes, indicating a more pronounced force response in athletes and electromyographic response in non-athletes.

Unilateral isometric muscle fatigue decreases force production and activation of contralateral knee extensors but not elbow flexors

2014 ◽  
Vol 39 (12) ◽  
pp. 1338-1344 ◽  
Author(s):  
Israel Halperin ◽  
David Copithorne ◽  
David G. Behm
Keyword(s):  
Muscle Fatigue ◽  
Force Production ◽  
Voluntary Activation ◽  
Knee Extensors ◽  
Elbow Flexors ◽  
Post Intervention ◽  
Nonlocal Effects ◽  
And Performance ◽  
Voluntary Contractions ◽  
Isometric Muscle

Nonlocal muscle fatigue occurs when fatiguing 1 muscle alters performance of another rested muscle. The purpose of the study was to investigate if fatiguing 2 separate muscles would affect the same rested muscle, and if fatiguing the same muscle would affect 2 separate muscles. Twenty-one trained males participated in 2 studies (n = 11; n = 10). Subjects performed 2 pre-test maximum voluntary contractions (MVCs) with the nondominant knee extensors. Thereafter they performed two 100-s MVCs with their dominant knee extensors, elbow flexors, or rested. Between and after the sets, a single MVC with the nondominant rested knee extensors was performed. Subsequently, 12 nondominant knee extensors repeated MVCs were completed. Force, quadriceps voluntary activation (VA), and electromyography (EMG) were measured. The same protocol was employed in study 2 except the nondominant elbow-flexors were tested. Study 1: Compared with control conditions, a significant decrease in nondominant knee extensors force, EMG, and VA was found under both fatiguing conditions (P ≤ 0.05; effect size (ES) = 0.91–1.15; 2%–8%). Additionally, decrements in all variables were found from the first post-intervention MVC to the last (P ≤ 0.05; ES = 0.82–2.40; 9%–20%). Study 2: No differences were found between conditions for all variables (P ≥ 0.33; ES ≤ 0.2; ≤3.0%). However, all variables decreased from the first post-intervention MVC to the last (P ≤ 0.05; ES = 0.4–3.0; 7.2%–19.7%). Whereas the rested knee extensors demonstrated nonlocal effects regardless of the muscle being fatigued, the elbow-flexors remained unaffected. This suggests that nonlocal effects are muscle specific, which may hold functional implications for training and performance.

scholarly journals Quadriceps Femoris and Hamstring Muscle Function in a Person With an Unstable Knee

1999 ◽  
Vol 79 (1) ◽  
pp. 66-75 ◽  
Author(s):  
Murray E Maitland ◽  
Stanley V Ajemian ◽  
Esther Suter
Keyword(s):  
Gait Analysis ◽  
Cruciate Ligament ◽  
Specific Treatment ◽  
Knee Extensor ◽  
Left Knee ◽  
Thigh Muscle ◽  
Knee Extensors ◽  
Term Outcome ◽  
Electromyographic Biofeedback ◽  
Muscle Inhibition

Abstract Background and Purpose. The purpose of this case report is to describe the evaluation, treatment, and short-term outcome for an individual with chronic, progressively worsening instability of the knee during gait associated with anterior cruciate ligament (ACL) insufficiency.Case Description. The patient was a 34-year-old man who sustained bilateral ACL injuries. Subsequently, an autograft reconstruction of the left knee ACL was performed. Eight months post-reconstruction, the left knee was unstable despite bracing. Gait analysis and tests to determine the presence of muscle inhibition were performed prior to and after 12 weeks of training. Isometric torque of the knee extensors and flexors was measured with the knee in 90 degrees of flexion. A training program primarily consisted of electromyographic biofeedback during thigh muscle exercises, balance exercises, and gait.Outcomes. Muscle inhibition decreased and maximal isometric knee flexion and extension torques increased during the 12-week training period. Gait analysis demonstrated a 50% decrease in the maximum knee extensor moment and an increase in walking speed.Discussion. Selected gait variables, torque production, and muscle inhibition may change in a person with an unstable knee. The measurement of variables that have previously been documented as mechanisms of knee instability during walking allows for the selection of a specific treatment approach.

Reliability and Validity of a Novel Trunk-Strength Assessment for High-Performance Sprint Flat-Water Kayakers

2019 ◽  
Vol 14 (4) ◽  
pp. 486-492
Author(s):  
Darren Steeves ◽  
Leo J. Thornley ◽  
Joshua A. Goreham ◽  
Matthew J. Jordan ◽  
Scott C. Landry ◽  
...  
Keyword(s):  
High Performance ◽  
Isometric Force ◽  
Reliability And Validity ◽  
Small Degree ◽  
Strong Correlations ◽  
Strength Assessment ◽  
Performance Times ◽  
Voluntary Contractions ◽  
Pearson Correlations ◽  
Maximal Isometric Force

Purpose: To determine the reliability and validity of a novel trunk maximal isometric force assessment involving 7 different tasks with 200-m times for elite sprint flat-water kayakers. Methods: Ten elite sprint flat-water kayakers performed a series of maximal isometric voluntary contractions (MVCs) on 2 separate days to assess reliability. MVC force was assessed as the participants sat on a modified kayak ergometer and applied their maximal isometric force to a uniaxial load cell during 7 different tasks. The 7 tasks of interest were a seated trunk-forward flexion, bilateral (left and right) rotational pulls, bilateral rotational pushes, and a sport-specific bilateral kayak-stroke simulation. Twenty elite flat-water kayak athletes (10 male and 10 female) participated in the validity portion by completing the series of tasks in conjunction with a 200-m race. Results: MVC force values ranged from 84 to 800 N across all participants and all tasks. The average coefficient of variation of the 7 tasks ranged from 2.4% to 7.7%. Regression analysis showed Pearson correlations ranging from −.84 to −.22 for both absolute and relative values with 200-m performance times. Conclusions: MVC force measured in each task was considered reliable as a small degree of variance between trials was found. The summation of the 7 trunk scores showed very strong correlations with on-water performance, indicating that this assessment is valid for elite sprint kayakers.

The Association of Obesity With Quadriceps Activation During Sit-to-Stand

2020 ◽  
Vol 100 (12) ◽  
pp. 2134-2143
Author(s):  
Lance M Bollinger ◽  
Amanda L Ransom
Keyword(s):  
Vastus Lateralis ◽  
Knee Extensor ◽  
Quadriceps Muscle ◽  
Knee Extensors ◽  
Emg Activity ◽  
Vastus Medialis ◽  
Trunk Flexion ◽  
Maximal Voluntary Isometric Contraction ◽  
Sit To Stand ◽  
The Mean

Abstract Objective Obesity reduces voluntary recruitment of quadriceps during single-joint exercises, but the effects of obesity on quadriceps femoris muscle activation during dynamic daily living tasks, such as sit-to-stand (STS), are largely unknown. The purpose of this study was to determine how obesity affects quadriceps muscle recruitment during STS. Methods In this cross-sectional study, 10 women who were lean and 17 women who were obese completed STS from a chair with arms crossed over the chest. Three-dimensional motion analysis was used to define 3 distinct phases (I–III) of the STS cycle. The electromyographic (EMG) activity of the vastus medialis, vastus lateralis, and semitendinosus was measured. Results STS duration was greater (3.02 [SD = 0.75] seconds vs 1.67 [SD = 0.28] seconds) and peak trunk flexion angle was lower (28.9 degrees [SD = 10.4 degrees] vs 35.8 degrees [SD = 10.1 degrees]) in the women who were obese than in the women who were lean. The mean EMG activity of the knee extensors increased from phase I to phase II in both groups; however, the mean EMG activities of both the vastus medialis (32.1% [SD = 16.6%] vs 47.3% [SD = 19.6%] maximal voluntary isometric contraction) and the vastus lateralis (31.8% [SD = 19.4%] vs 47.5% [SD = 19.6%] maximal voluntary isometric contraction) were significantly lower during phase II in the women who were obese. The mean EMG activity of the semitendinosus increased throughout STS but was not significantly different between the 2 groups. Coactivation of the semitendinosus and knee extensors tended to be greater in the women who were obese but failed to reach statistical significance. Conclusions Knee extensor EMG amplitude was reduced in women who were obese during STS, despite reduced trunk flexion. Impact Reduced knee extensor recruitment during STS in obesity may redistribute forces needed to complete this task to other joints. Functional movement training may help improve knee extensor recruitment during STS in people who are obese. Lay Summary People with obesity often have low quadriceps muscle strength and impaired mobility during daily activities. This study shows that women who are obese have lower voluntary recruitment of quadriceps when rising from a chair than women who are lean do, which could increase workload on hip or ankle muscles during this important daily task. Quadriceps strengthening exercises might improve the ability to rise from sitting to standing.

scholarly journals Comparison of Recovery Strategies on Maximal Force-Generating Capacity and Electromyographic Activity Level of the Knee Extensor Muscles

2011 ◽  
Vol 46 (4) ◽  
pp. 386-394 ◽  
Author(s):  
Nidhal Zarrouk ◽  
Haithem Rebai ◽  
Abdelmoneem Yahia ◽  
Nizar Souissi ◽  
François Hug ◽  
...  
Keyword(s):  
Knee Extensor ◽  
Neuromuscular Fatigue ◽  
Activity Level ◽  
Knee Extensors ◽  
Emg Activity ◽  
Electromyographic Activity ◽  
Active Recovery ◽  
Concentric Exercise ◽  
Extensor Muscles ◽  
Knee Extensor Muscles

Context: With regard to intermittent training exercise, the effects of the mode of recovery on subsequent performance are equivocal. Objective: To compare the effects of 3 types of recovery intervention on peak torque (PT) and electromyographic (EMG) activity of the knee extensor muscles after fatiguing isokinetic intermittent concentric exercise. Design: Crossover study. Setting: Research laboratory. Patients or Other Participants: Eight elite judo players (age = 18.4 ± 1.4 years, height = 180 ± 3 cm, mass = 77.0 ± 4.2 kg). Intervention(s): Participants completed 3 randomized sessions within 7 days. Each session consisted of 5 sets of 10 concentric knee extensions at 80% PT at 120°/s, with 3 minutes of recovery between sets. Recovery interventions were passive, active, and electromyostimulation. The PT and maximal EMG activity were recorded simultaneously while participants performed isokinetic dynamometer trials before and 3 minutes after the resistance exercise. Main Outcome Measure(s): The PT and maximal EMG activity from the knee extensors were quantified at isokinetic velocities of 60°/s, 120°/s, and 180°/s, with 5 repetitions at each velocity. Results: The reduction in PT observed after electromyo-stimulation was less than that seen after passive (P < .001) or active recovery (P < .001). The reduction in PT was less after passive recovery than after active recovery (P < .001). The maximal EMG activity level observed after electromyostimulation was higher than that seen after active recovery (P < .05). Conclusions: Electromyostimulation was an effective recovery tool in decreasing neuromuscular fatigue after high-intensity, intermittent isokinetic concentric exercise for the knee extensor muscles. Also, active recovery induced the greatest amount of neuromuscular fatigue.

Elbow flexor fatigue modulates central excitability of the knee extensors

2015 ◽  
Vol 40 (9) ◽  
pp. 924-930 ◽  
Author(s):  
Saied Jalal Aboodarda ◽  
David B. Copithorne ◽  
Kevin E. Power ◽  
Eric Drinkwater ◽  
David G. Behm
Keyword(s):  
Action Potential ◽  
Compound Muscle Action Potential ◽  
Knee Extensor ◽  
Elbow Flexion ◽  
Elbow Flexor ◽  
Emg Activity ◽  
Muscle Action ◽  
Muscle Action Potential ◽  
Extensor Muscles ◽  
Knee Extensor Muscles

The present study investigated the effects of exercise-induced elbow flexor fatigue on voluntary force output, electromyographic (EMG) activity and motoneurone excitability of the nonexercised knee extensor muscles. Eleven participants attended 3 testing sessions: (i) control, (ii) unilateral fatiguing elbow flexion and (iii) bilateral fatiguing elbow flexion (BiFlex). The nonfatigued knee extensor muscles were assessed with thoracic motor evoked potentials (TMEPs), maximal compound muscle action potential (Mmax), knee extensor maximal voluntary contractions (MVCs), and normalized EMG activity before and at 30 s, 3 min, and 5 min postexercise. BiFlex showed significantly lower (Δ = −18%, p = 0.03) vastus lateralis (VL) normalized EMG activity compared with the control session whereas knee extension MVC force did not show any statistical difference between the 3 conditions (p = 0.12). The TMEP·Mmax−1 ratio measured at the VL showed a significantly higher value (Δ = +46%, p = 0.003) following BiFlex compared with the control condition at 30 s postexercise. The results suggest that the lower VL normalized EMG following BiFlex might have been due to a reduction in supraspinal motor output because spinal motoneuronal responses demonstrated substantially higher value (30 s postexercise) and peripheral excitability (compound muscle action potential) showed no change following BiFelex than control condition.

scholarly journals A Biomechanical Investigation of A Single-Limb Squat: Implications for Lower Extremity Rehabilitation Exercise

2008 ◽  
Vol 43 (5) ◽  
pp. 477-482 ◽  
Author(s):  
Jim Richards ◽  
Dominic Thewlis ◽  
James Selfe ◽  
Andrew Cunningham ◽  
Colin Hayes
Keyword(s):  
Repeated Measures ◽  
Knee Flexion ◽  
Knee Extensor ◽  
Rectus Femoris ◽  
Knee Extensors ◽  
Emg Activity ◽  
Repeated Measures Design ◽  
Biomechanical Investigation ◽  
Rehabilitative Intervention ◽  
Integrated Emg

Abstract Context: Single-limb squats on a decline angle have been suggested as a rehabilitative intervention to target the knee extensors. Investigators, however, have presented very little empirical research in which they have documented the biomechanics of these exercises or have determined the optimum angle of decline used. Objective: To determine the involvement of the gastrocnemius and rectus femoris muscles and the external ankle and knee joint moments at 60° of knee flexion while performing a single-limb squat at different decline angles. Design: Participants acted as their own controls in a repeated-measures design. Patients or Other Participants: We recruited 10 participants who had no pain, injury, or neurologic disorder. Intervention(s): Participants performed single-limb squats at different decline angles. Main Outcome Measure(s): Angle-specific knee and ankle moments were calculated at 60° of knee flexion. Angle-specific electromyography (EMG) activity was calculated at 60° of knee flexion. Integrated EMG also was calculated to determine the level of muscle activity over the entire squat. Results: An increase was seen in the knee moments (P < .05) and integrated EMG in the rectus femoris (P < .001) as the decline angle increased. A decrease was seen in the ankle moments as the decline angle increased (P  =  .001), but EMG activity in the gastrocnemius increased between 16° and 24° (P  =  .018). Conclusions: As the decline angle increased, the knee extensor moment and EMG activity increased. As the decline angle increased, the ankle plantar-flexor moments decreased; however, an increase in the EMG activity was seen with the 24° decline angle compared with the 16° decline angle. This indicates that decline squats at an angle greater than 16° may not reduce passive calf tension, as was suggested previously, and may provide no mechanical advantage for the knee.

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