The Influence of Elbow Joint Angle on Different Phases of Force Development During Maximal Voluntary Contraction

The first aim of the study was to find an elbow joint angle at which muscle can produce maximum voluntary force (Lo(MVC)) and to compare that angle with an angle at which the fastest rates of force development occur (Lo). The second aim of the study was to find if changes in MVC and force development speed at an angle smaller (Ls) and larger (Ll) than the optimal angle depend on whether Ls and Ll were compared to Lo or Ls and Ll to Lo(MVC) Twenty-four male physical education students were tested four times using the BIODYNA dynamometer to measure torque versus time at an optimal length, as well as at lengths that were shorter (Ls = optimal −30°) and longer (Ll = optimal + 50°). The average values of optimal angles for force development indices (Lo) were similar to the angle at which maximum force was produced (Lo(MVC)); however, there was a small (5 - 10°) difference between Lo and Lo(MVO) in the majority of subjects.The results showed that during elbow flexion with the forearm in the midrange position the difference between Lo and Lo(MVC) was small and did not affect MVC; however, it had a significant effect on the relation between joint angle and force development speed. Key words: optimal length, force development, MVC, elbow joint angle

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

Journal of Neurophysiology ◽

10.1152/jn.00620.2018 ◽

2019 ◽

Vol 122 (1) ◽

pp. 413-423 ◽

Cited By ~ 2

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.

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Plasma Actin, Gelsolin and Orosomucoid Levels after Eccentric Exercise

Journal of Human Kinetics ◽

10.1515/hukin-2017-0027 ◽

2017 ◽

Vol 56 (1) ◽

pp. 99-108 ◽

Cited By ~ 5

Author(s):

Éva Tékus ◽

Márk Váczi ◽

Zoltán Horváth-Szalai ◽

Andrea Ludány ◽

Tamás Kőszegi ◽

...

Keyword(s):

Blood Plasma ◽

Eccentric Exercise ◽

Muscle Soreness ◽

Acute Effect ◽

Voluntary Contraction ◽

Education Students ◽

Post Exercise ◽

Physical Education Students ◽

Significant Difference ◽

Exercise Induced

Abstract The present study investigated the acute effect of eccentric exercise on blood plasma actin, gelsolin (GSN) and orosomucoid (AGP) levels in untrained and moderately trained individuals, and their correlation with exercise induced muscle damage (EIMD) markers (CK, intensity of muscle soreness and maximal voluntary contraction torque deficit). Healthy physical education students (6 untrained, 12 moderately trained) participated in this research. Actin, GSN, AGP and CK levels were measured in blood plasma at baseline, immediately, 1 h, 6 h and 24 h post-exercise comprising 90 eccentric quadriceps contractions performed on a dynamometer. There was significant time main effect for GSN, AGP, CK and significant difference was found between baseline and the lowest value of post-exercise GSN (p < 0.05), as well as baseline and the highest value of post-exercise AGP (p < 0.05). Relationships were found between GSN levels and other indirect EIMD markers (between all GSN levels at post-exercise and CK activity at 6 h, p < 0.05; GSNMIN and muscle soreness at post-exercise, p < 0.04), GSN and AGP; however, actin did not correlate at any time points with GSN. Actin, GSN, AGP and CK responses after eccentric exercise do not seem sensitive to training status. The plasma actin level is used as an indicator of injury, however, our results suggest that it is not an accurate marker of EIMD, while plasma GSN concentrations show a better relationship with EIMD and the post-exercise inflammatory process. The elevated plasma AGP and the correlation between GSN and AGP seem to be promising for assessment of exercise-induced muscle injury.

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Computerized measurements of radiographic anatomical parameters of the elbow joint in Bernese Mountain Dogs

Veterinary and Comparative Orthopaedics and Traumatology ◽

10.3415/vcot-11-06-0082 ◽

2012 ◽

Vol 25 (03) ◽

pp. 250-261 ◽

Cited By ~ 6

Author(s):

H. G. Schmoekel ◽

H. Waibl ◽

L. Brunnberg ◽

S. Stein

Keyword(s):

Elbow Joint ◽

Elbow Flexion ◽

Opening Angle ◽

Radiographic Analysis ◽

Kind Permission ◽

Elbow Dysplasia ◽

The Difference ◽

Area X ◽

Humeral Condyle ◽

Anatomical Parameters

SummaryObjective: Comparison of two methods for evaluation of anatomical parameters of elbow joints in Bernese Mountain Dogs.Study design: Radiographic analysis.Animals: Nine hundred and thirty-one radiographs of elbow joints from 305 Bernese Mountain Dogs.Material and methods: The angles OL, PA, RA and UL were measured according to the Mues method and the Radius of the humeral condyle, Opening angle beta, Quotient Q and Ae, Area X, Step 1 and Step 2 according to the Viehmann method. The radiographs were divided according to their angle of flexion into five groups: 0–30°, 31–60°, 61–90°, 91–120° and >120°. The difference and the correlation between measured values and the elbow dysplasia (ED) score was calculated and compared.Results: The average values of angle OL, PA and RA, Area X, Step 1 and Step 2 were significantly different within the different elbow flexion angle groups. The values of Opening angle beta, Quotients Q and Ae as well as Radius of the humeral condyle varied independently from the degree of the elbow flexion on the radiograph. The angles OL, PA and RA and the Radius of the humeral condyle, the Opening angle beta, the Quotients Q and Ae, Step 1 and Step 2 correlated with the ED score.Conclusion: In contrast to the method of Mues, the majority of the measured parameters of the method of Viehmann were not influenced by the degree of flexion of the elbow joint and correlated with the ED score. Clinical relevance: The method of Viehmann warrants consideration for the evaluation of radiographs of elbow joints in the Bernese Mountain Dog for ED.This article is based on a study first reported in S. Stein's doctoral thesis, which was presented on 08.05.2007 and published thereafter in full by Mensch & Buch Verlag. This abridged and translated version is now being published with the kind permission of Mensch & Buch Verlag.

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