Influence of Arm Positions on Emg-Reaction Time of the Biceps Brachii for Elbow Flexion and Forearm Supination

1984 ◽  
Vol 59 (1) ◽  
pp. 191-194 ◽  
Author(s):  
Reiji Taniguchi ◽  
Ryuichi Nakamura ◽  
Tatsuya Kasai
Keyword(s):  
Reaction Time ◽  
Elbow Joint ◽  
Biceps Brachii ◽  
Muscle Length ◽  
Elbow Flexion ◽  
Normal Subjects ◽  
Biceps Brachii Muscle ◽  
Prime Mover

The influence of starting positions of the arm on EMG-RTs of the biceps brachii muscle for elbow flexion and forearm supination was examined using 16 normal subjects. Two angles of the elbow joint, 45° and 110° flexion, and two positions of the forearm, 45° supination and 90° pronation, were used as the factorial combinations of all four. The EMG-RT for elbow flexion decreased in the order of 110° Pronation > 45° Pronation = 110° Supination > 45° Supination, and that for forearm supination decreased in the order of 45° Supination > 45° Pronation = 110° Supination > 110° Pronation. These results were kinesiologically interpreted that variations of EMG-RTs were based on the change in the number of synergic muscles participating in an intended movement and the muscle length of the prime mover at the start of the movement.

scholarly journals Muscle length and joint angle influence spinal but not corticospinal excitability to the biceps brachii across forearm postures

2019 ◽  
Vol 122 (1) ◽  
pp. 413-423 ◽  
Author(s):  
Davis A. Forman ◽  
Daniel Abdel-Malek ◽  
Christopher M. F. Bunce ◽  
Michael W. R. Holmes
Keyword(s):  
Isometric Contraction ◽  
Elbow Joint ◽  
Joint Angle ◽  
Biceps Brachii ◽  
Motor Evoked Potentials ◽  
Muscle Length ◽  
Elbow Flexion ◽  
Corticospinal Excitability ◽  
Biceps Brachii Muscle ◽  
Spinal Excitability

Forearm rotation (supination/pronation) alters corticospinal excitability to the biceps brachii, but it is unclear whether corticospinal excitability is influenced by joint angle, muscle length, or both. Thus the purpose of this study was to separately examine elbow joint angle and muscle length on corticospinal excitability. Corticospinal excitability to the biceps and triceps brachii was measured using motor evoked potentials (MEPs) elicited via transcranial magnetic stimulation. Spinal excitability was measured using cervicomedullary motor evoked potentials (CMEPs) elicited via transmastoid electrical stimulation. Elbow angles were manipulated with a fixed biceps brachii muscle length (and vice versa) across five unique postures: 1) forearm neutral, elbow flexion 90°; 2) forearm supinated, elbow flexion 90°; 3) forearm pronated, elbow flexion 90°; 4) forearm supinated, elbow flexion 78°; and 5) forearm pronated, elbow flexion 113°. A musculoskeletal model determined biceps brachii muscle length for postures 1–3, and elbow joint angles ( postures 4–5) were selected to maintain biceps length across forearm orientations. MEPs and CMEPs were elicited at rest and during an isometric contraction of 10% of maximal biceps muscle activity. At rest, MEP amplitudes to the biceps were largest during supination, which was independent of elbow joint angle. CMEP amplitudes were not different when the elbow was fixed at 90° but were largest in pronation when muscle length was controlled. During an isometric contraction, there were no significant differences across forearm postures for either MEP or CMEP amplitudes. These results highlight that elbow joint angle and biceps brachii muscle length can each independently influence spinal excitability. NEW & NOTEWORTHY Changes in upper limb posture can influence the responsiveness of the central nervous system to artificial stimulations. We established a novel approach integrating neurophysiology techniques with biomechanical modeling. Through this approach, the effects of elbow joint angle and biceps brachii muscle length on corticospinal and spinal excitability were assessed. We demonstrate that spinal excitability is uniquely influenced by joint angle and muscle length, and this highlights the importance of accounting for muscle length in neurophysiological studies.

Movement Precuing Altered Reaction Time of Elbow Flexion and Forearm Supination

1987 ◽  
Vol 65 (3) ◽  
pp. 799-802 ◽  
Author(s):  
Toru Hosokawa ◽  
Ryuichi Nakamura ◽  
Yoshiaki Yamada
Keyword(s):  
Reaction Time ◽  
Healthy Subjects ◽  
Biceps Brachii ◽  
Movement Pattern ◽  
Elbow Flexion ◽  
Biceps Brachii Muscle

Electromyographic reaction time (EMG-RT) of the biceps brachii muscle for elbow flexion and forearm supination was investigated in 10 healthy subjects under two conditions of movement precuing and nonprecuing with a constant foreperiod. Analysis showed that the precuing significantly reduced EMG-RT of both movements, especially the supination, and confirmed previous finding that the supination had an advantage in initiation over the flexion when the movement pattern was prepared in advance. When not prepared, on the contrary, EMG-RT of supination significantly prolonged as compared with flexion.

Is the Reduction of Reaction Time an Adequate Estimate of the Effect of Practice?

1988 ◽  
Vol 66 (1) ◽  
pp. 51-56 ◽  
Author(s):  
Tatsuya Kasai
Keyword(s):  
Reaction Time ◽  
Biceps Brachii ◽  
Movement Patterns ◽  
Elbow Flexion ◽  
Practice Effect ◽  
Biceps Brachii Muscle ◽  
Critical Importance ◽  
Before And After ◽  
Initial Sessions

The purpose of this study was to determine whether the reduction of reaction time is an adequate estimate of the effect of practice. Since the biceps brachii muscle performs in two different movement patterns, elbow flexion and forearm supination, EMG-RTs of these movement patterns were examined after forehand-stroke practice by the preferred hand. Moreover, for the purpose of analysis of the return of practice effect, the EMG-RTs of the same subjects were measured 3 or 4 mo. after the initial sessions. No significant differences in EMG-RTs of elbow flexion and forearm supination of both hands were recognized before and after practice. The EMG-RT differences for the nonpracticed hand were nonsignificant, but those for the practiced hand were significant. These results suggest that the reduction in reaction time alone is an inadequate parameter for estimating the effect of practice. Further, it is of critical importance to find a potentially more reliable and valuable parameter such as the EMG-RT difference between the two different movement patterns.

Mechanical Evaluation of the Pronator Teres Rerouting Tendon Transfer

2004 ◽  
Vol 29 (3) ◽  
pp. 257-262 ◽  
Author(s):  
H. E. J. VEEGER ◽  
M. KREULEN ◽  
M. J. C. SMEULDERS
Keyword(s):  
Biceps Brachii ◽  
External Rotation ◽  
Three Dimensional ◽  
Muscle Length ◽  
Biomechanical Model ◽  
Elbow Flexion ◽  
Axial Rotation ◽  
Original Position ◽  
Pronator Quadratus ◽  
Pronator Teres

We simulated pronator teres rerouting using a three-dimensional biomechanical model of the arm. Simulations comprised the evaluation of changes in muscle length and the moment arm of pronator teres with changes in forearm axial rotation and elbow flexion. The rerouting of Pronator Teres was simulated by defining a path for it through the interosseous membrane with re-attachment to its original insertion. However the effect of moving the insertion to new positions, 2 cm below and above, the original position was also assessed. The effect on total internal rotation and external rotation capacity was determined by calculating the potential moments for pronator teres, supinator, pronator quadratus, biceps brachii and brachioradialis. Pronator teres was found to be a weak internal rotator in extreme pronation, but a strong internal rotator in neutral rotation and in supination. After rerouting pronator teres was only a strong external rotator in full pronation and not at other forearm positions, where the effect of rerouting was comparable to a release procedure.

Mind-Muscle Connection: Verbal Instructions Alter Electromyographic Activity for Elbow Flexors and Extensors During Co-Contraction Training

2020 ◽  
pp. 003151252094908
Author(s):  
Rafael A. Fujita ◽  
Marina M. Villalba ◽  
Nilson R. S. Silva ◽  
Matheus M. Pacheco ◽  
Matheus M. Gomes
Keyword(s):  
Strength Training ◽  
Elbow Joint ◽  
Biceps Brachii ◽  
Elbow Flexion ◽  
Emg Activity ◽  
Elbow Extension ◽  
Verbal Instruction ◽  
Triceps Brachii ◽  
Verbal Instructions ◽  
Lateral Head

Co-contraction training has demonstrated similar electromyographic (EMG) activity levels compared to conventional strength training. Since verbal instructions can increase EMG activity on target muscles during conventional exercises, the same should occur during co-contraction. In this study we analyzed whether different verbal instructions would alter the EMG activity of target muscles - biceps brachii (BB) and triceps brachii lateral head (TB) - during co-contraction training for the elbow joint. Seventeen males with experience in strength training performed a co-contraction set in two verbal instruction conditions to emphasize either elbow flexion or elbow extension. Surface electrodes were fixed over biceps brachii and triceps brachii lateral head muscles. We measured EMG mean amplitude and analyzed data with 2-way ANOVA. We found a significant interaction between muscle and verbal instruction ( p = 0.002). Post hoc tests indicated that verbal instructions ( p = 0.001) influenced the BB EMG activity (elbow flexion: M = 68.74, SD = 17.96%; elbow extension: M = 53.47, SD = 16.13%); and also showed difference ( p = 0.006) in the EMG activity between BB and TB with verbal instruction emphasizing the elbow extension (BB: M = 53.47, SD = 16.13%; TB: M = 69.18, SD = 21.79%). There was a difference in the EMG ratio of BB/TB ( p = 0.001) when focusing on elbow flexion ( M = 1.09, SD = 0.30) versus elbow extension ( M = 0.81, SD = 0.25). As verbal instruction modified the magnitude of muscle recruitment during co-contractions for elbow joint muscles, there is a clear mind-muscle connection of importance to this method of training. Also, of importance to trainers, verbal instructions seemed to affect individuals differentially.

Effect of Reaction Time Condition on EMG Activities of the Biceps Brachii Muscle in Elbow Flexion and Forearm Supination

1988 ◽  
Vol 67 (3) ◽  
pp. 807-813
Author(s):  
Jose Alvin P. Mojica ◽  
Ryuichi Nakamura ◽  
Yoshiaki Yamada ◽  
Ichiro Tsuji
Keyword(s):  
Biceps Brachii ◽  
Elbow Flexion ◽  
Emg Activity ◽  
Biceps Brachii Muscle ◽  
Response Uncertainty ◽  
Motor Set ◽  
Temporal And Spatial ◽  
Temporal And Spatial Characteristics ◽  
Spatial Specificity ◽  
Simple Rt

Under simple- and choice-RT conditions, the biceps brachii muscle was examined in 8 healthy male subjects to determine how the temporal and spatial characteristics of elbow flexion and forearm supination differed at the initial phase of EMG activity and whether preparation or the presence of response uncertainty influenced the EMG outputs of the two movements. In the simple-RT condition, RT of supination was significantly faster than that of flexion but EMG activity of supination was less than that of flexion. In contrast, in the choice-RT condition, RT of flexion was significantly faster than that of supination but EMG activity of flexion was significantly reduced compared to supination. These findings indicate that advanced preparation or motor set facilitates the differentiation of RTs and EMG activities of the response movements and that response uncertainty causes a significant change in the temporal and spatial specificity of both elbow flexion and forearm supination.

scholarly journals Placing Greater Torque at Shorter or Longer Muscle Lengths? Effects of Cable vs. Barbell Preacher Curl Training on Muscular Strength and Hypertrophy in Young Adults

2020 ◽  
Vol 17 (16) ◽  
pp. 5859
Author(s):  
João Pedro Nunes ◽  
Jeferson L. Jacinto ◽  
Alex S. Ribeiro ◽  
Jerry L. Mayhew ◽  
Masatoshi Nakamura ◽  
...  
Keyword(s):  
Young Adults ◽  
Resistance Training ◽  
Muscular Strength ◽  
Biceps Brachii ◽  
Muscle Length ◽  
Elbow Flexion ◽  
Peak Torque ◽  
Resistance Training Program ◽  
Pulley System ◽  
Isokinetic Torque

Muscular strength and hypertrophy following resistance training may be obtained in different degrees depending on the approach performed. This study was designed to compare the responses of the biceps brachii to two preacher curl exercises, one performed on a cable-pulley system (CAB; in which a greater torque was applied during the exercise when elbows were flexed and biceps shortened) and one performed with a barbell (BAR; in which greater torque was applied when the elbows were extended and biceps stretched). Thirty-five young adults (CAB: 13 men, 5 women; BAR: 12 men, 5 women; age = 24 ± 5 years) performed a resistance training program three times per week for 10 weeks, with preacher curl exercises performed in three sets of 8–12 repetitions. Outcomes measured included elbow flexion peak isokinetic torque at angles of 20°, 60°, and 100° (considering 0° as elbow extended), and biceps brachii thickness (B-mode ultrasound). Following the training period, there were significant increases for both groups in elbow flexion peak torque at the 20° (CAB: 30%; BAR = 39%; p = 0.046), 60° (CAB: 27%; BAR = 32%; p = 0.874), and 100° (CAB: 17%; BAR = 19%; p = 0.728), and biceps brachii thickness (CAB: 7%; BAR = 8%; p = 0.346). In conclusion, gains in muscular strength were greater for BAR only at longer muscle length, whereas hypertrophy was similar regardless of whether torque emphasis was carried out in the final (CAB) or initial (BAR) degrees of the range of motion of the preacher curl in young adults.

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