The isometric functional capacity of muscles that cross the elbow

Murray, Wendy M.; Buchanan, Thomas S.; Delp, Scott L.

doi:10.1016/s0021-9290(00)00051-8

Cited by 295 publications

(255 citation statements)

References 32 publications

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“…Like other studies (Murray et al, 2000), we found substantial variability in sarcomere lengths of the muscles measured here. Representing these sarcomere lengths by their mean value does not capture this variability; however, we divided the muscles into sub-regions in order to determine differences in force and moment generating capacity across the muscle width.…”

Section: Discussionsupporting

confidence: 84%

“…Fascicles were mounted on slides with Kaiser's jelly and coverslipped. A custom built diffractometer was used to measure sarcomere lengths (Lieber et al, 1990;Murray et al, 2000;Delp et al, 2001). The wavelength, k, of the 5 mW helium-neon laser was 632.8 nm.…”

Section: Methodsmentioning

confidence: 99%

“…To determine how muscle architecture and moment arm influence muscle function, the forcelength relationship and maximum isometric moment generating capacity for each muscle subregion was estimated (Loren et al, 1996;Murray et al, 2000). Force-length relationships were estimated for each muscle sub-region of each specimen for glenohumeral rotation for the position of 10° abduction.…”

Section: Methodsmentioning

confidence: 99%

“…Measuring all parameters on the same specimens will allow for determination of parameter covariance. However, only two studies conducted at the wrist (Loren et al, 1996), and at the elbow (Murray et al, 2000), have measured all parameters on the same specimens.…”

Section: Introductionmentioning

confidence: 99%

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Variability in isometric force and moment generating capacity of glenohumeral external rotator muscles

Langenderfer

Patthanacharoenphon

Carpenter

et al. 2006

Clinical Biomechanics

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Background. Muscles which cause glenohumeral external rotation possess varying ability for generating force and moment due to differences in muscle architecture, moment arm, and the interaction of these two factors. This study's purpose was to determine a complete dataset of muscletendon parameters for predicting the moment generating capacity and force-length dependence for external rotation of infraspinatus, supraspinatus and teres minor muscles.Methods. Muscle fascicle length, sarcomere length, pennation angle, and muscle volume were measured for sub-regions of infraspinatus and supraspinatus, and teres minor from 10 glenohumeral specimens. Tendon excursion was measured for glenohumeral rotation. From these parameter measurements, optimal fascicle length, physiological cross-sectional area, muscle force-length dependence, and maximum isometric moment generating capacity were calculated.Findings. Substantial differences were found for optimal muscle length, physiologic cross-sectional area, and tendon length for the 10 specimens of this study. Muscle sub-region had a significant effect on the force-length relationship for infraspinatus (P < 0.001), but was not significant for supraspinatus (P = 0.49). For infraspinatus and supraspinatus, maximum isometric rotation moment capacity was greater at 10° versus 60° abduction (P < 0.001). Maximum isometric rotation moment capacity for the teres minor was greater at 10° versus 60° abduction (P < 0.01). Sub-regions demonstrated significant differences in isometric moment capacity (P < 0.001).Interpretation. Functional capabilities of these muscles depend on muscle architecture and moment arm as well as their combined effects. The results allow for development of stochastic and deterministic models of glenohumeral external rotation strength which can be used for prediction of muscle forces and joint moments.

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Section: Discussionsupporting

confidence: 84%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Variability in isometric force and moment generating capacity of glenohumeral external rotator muscles

Langenderfer

Patthanacharoenphon

Carpenter

et al. 2006

Clinical Biomechanics

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“…The muscle parameters, F MAX , tendon slack-length (l SE 0 ), l CE_opt and moment arms of the four lumped muscles were obtained from Nijhof and Kouwenhoven (2000) and Murray et al (1995Murray et al ( , 2000. The contribution of the individual muscle parameters to the parameters of the lumped muscles depended on the relative contribution of the muscle to the total joint moment.…”

Section: Methodsmentioning

confidence: 99%

A model of open-loop control of equilibrium position and stiffness of the human elbow joint

2006

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According to the equilibrium point theory, the control of posture and movement involves the setting of equilibrium joint positions (EP) and the independent modulation of stiffness. One model of EP control, the α-model, posits that stable EPs and stiffness are set open-loop, i.e. without the aid of feedback. The purpose of the present study was to explore for the elbow joint the range over which stable EPs can be set open-loop and to investigate the effect of co-contraction on intrinsic low-frequency elbow joint stiffness (K ilf ). For this purpose, a model of the upper and lower arm was constructed, equipped with Hill-type muscles. At a constant neural input, the isometric force of the contractile element of the muscles depended on both the myofilamentary overlap and the effect of sarcomere length on the sensitivity of myofilaments to [Ca 2+ ] (LDCS). The musculoskeletal model, for which the parameters were chosen carefully on the basis of physiological literature, captured the salient isometric properties of the muscles spanning the elbow joint. It was found that stable open-loop EPs could be achieved over the whole range of motion of the elbow joint and that K ilf , which ranged from 18 to 42 N m·rad −1 , could be independently controlled. In the model, LDCS contributed substantially to K ilf (up to 25 N m·rad −1 ) and caused K ilf to peak at a sub-maximal level of co-contraction.

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Biomechanics of Strength and Strength Training

Zatsiorsky¹

2003

Strength and Power in Sport

148

133

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The objective of this lecture is to systematize and convey biomechanical knowledge to athletic practitioners, specifically coaches.By definition, strength, or muscular strength, is the ability to exert maximal external force.Three main problems exist in strength conditioning for qualified athletes: 1. Exercise selection -which exercises should be used by the athlete; 2. Training load, in particular training intensity and volume; and 3. Training timing, i.e. the distribution of the exercises and load over the time periods. The problem of the exercise selection only, in particular its biomechanical aspects, is covered in this lecture. EXERCISE SPECIFlCITY. As adaptations effects are specific, the exercises employed in training need to correspond with the main spon exercise. The degree of this correspondence, or similarity, is called specijicay of the training exercise. The specificity of training directly reflects its efficiency and deserves thoughtful attention by the coach. A main tendency in the modern training of elite athletes is the increased percentage of specific exercises. Contemporary sport training is, in general, more specific than training in the past.In various sports, exercise specificity is determined by different factors. In strength and power sports, the movement coordination, in the broad sense of this term, is scrutinized. Main sport exercises with additional resistanceRequirements for the exercise specificity are best met when the main sport movement, with increased (added) resistance, is used for training.Resistance in athletic events can be increased in various ways.(a) Add i t ion a I w e i g h t. Implements of heavier weight such as weight vests, belts, hand cuffs, ankle cuffs, etc. may be worn. While this approach is simple, it should be noted that the demand for the venical force (acting against gravity) principally increases with supplementary weight. Exercising with additional weight requires that force is exerted in an inappropriate direction, i.e.too venically.(b) Up h i J I a m b u I a t ion (running, walking, skiing, etc). This practice is limited by the possible changes in spon technique.(c) Re tar din g the at hie t e 's pro g res S ion; for example, running with a harness, towing a sled, or a pulley machine with a weight stack. These methods are cumbersome in that the equipment is bulky and heavy.(d) I n c rea sed a e rod y n a mic res i s tan c e. This method is very popular among elite athletes in spons such as speed Skating, running, and others. Small parachutes are used for this pU!1'0se. When the athlete runs, the parachute inflates, which creates a drag force. The higher the running velocity, the greater the resistance force. Assistance exercisesA variety of strength exercises, beyond the main sport exercise, are used in the training routines of athletes. The selection of strength exercises for qualified athletes is J

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The isometric functional capacity of muscles that cross the elbow

Cited by 295 publications

References 32 publications

Variability in isometric force and moment generating capacity of glenohumeral external rotator muscles

Variability in isometric force and moment generating capacity of glenohumeral external rotator muscles

A model of open-loop control of equilibrium position and stiffness of the human elbow joint

Biomechanics of Strength and Strength Training

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