Elastic properties of the cat soleus tendon and their functional importance.

Rack, P. M. H.; Westbury, D. R.

doi:10.1113/jphysiol.1984.sp015077

Cited by 164 publications

(110 citation statements)

References 25 publications

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“…The question as to whether the stiffness of the aponeurosis is similar to the stiffness of the free tendon is controversial. Some studies on animal muscles show that the stiffness of aponeurosis and the free tendon is similar (Rack and Westbury, 1984;Scott and Loeb, 1995;Trestik and Lieber, 1993) while other studies on animal muscles find differences (Ettema and Huijing, 1989;Lieber et al, 2000;Lieber et al, 1991). Ultrasonographic studies of human muscles also give discordant results.…”

Section: Discussionmentioning

confidence: 71%

Passive mechanical properties of human gastrocnemius muscle–tendon units, muscle fascicles and tendonsin vivo

Hoang

Herbert

Todd

et al. 2007

Journal of Experimental Biology

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SUMMARY This study provides the first in vivo measures of the passive length–tension properties of relaxed human muscle fascicles and their tendons. A new method was used to derive passive length–tension properties of human gastrocnemius muscle–tendon units from measures of ankle stiffness obtained at a range of knee angles. Passive length–tension curves of the muscle–tendon unit were then combined with ultrasonographic measures of muscle fascicle length and pennation to determine passive length–tension curves of the muscle fascicles and tendons. Mean slack lengths of the fascicles, tendons and whole muscle–tendon units were 3.3±0.5 cm, 39.5±1.6 cm and 42.3±1.5 cm, respectively (means ± s.d., N=6). On average, the muscle–tendon units were slack (i.e. their passive tension was zero) over the shortest 2.3±1.2 cm of their range. With combined changes of knee and ankle angles, the maximal increase in length of the gastrocnemius muscle–tendon unit above slack length was 6.7±1.9 cm, of which 52.4±11.7% was due to elongation of the tendon. Muscle fascicles and tendons underwent strains of 86.4±26.8% and 9.2±4.1%, respectively, across the physiological range of lengths. We conclude that the relaxed human gastrocnemius muscle–tendon unit falls slack over about one-quarter of its in vivo length and that muscle fascicle strains are much greater than tendon strains. Nonetheless, because the tendons are much longer than the muscle fascicles, tendons contribute more than half of the total compliance of the muscle–tendon unit.

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Section: Discussionmentioning

confidence: 71%

Passive mechanical properties of human gastrocnemius muscle–tendon units, muscle fascicles and tendonsin vivo

Hoang

Herbert

Todd

et al. 2007

Journal of Experimental Biology

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“…In vivo it is very difficult to do this, because of the differences in the anthropometrical characteristics of the subjects and also the differences in the localisation of the ultrasound probe (it is practically impossible to place the ultrasound probe exactly at the same position at all experiments). Differences in the rest length would influence the calculated stiffness (relationship between tendon force and elongation) of the tendon and aponeurosis (Rack and Westbury, 1984;Muramatsu et al, 2001;Arampatzis et al, 2005a;Stafilidis et al, 2005). This fact makes it difficult to compare the stiffness between different subjects or groups.…”

Section: Measurement Of Tendinous Tissue Elongationmentioning

confidence: 99%

Influence of the muscle-tendon unit's mechanical and morphological properties on running economy

Arampatzis

Monte

Karamanidis

et al. 2006

Journal of Experimental Biology

205

203

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SUMMARY The purpose of this study was to test the hypothesis that runners having different running economies show differences in the mechanical and morphological properties of their muscle-tendon units (MTU) in the lower extremities. Twenty eight long-distance runners (body mass: 76.8±6.7 kg, height: 182±6 cm, age: 28.1±4.5 years) participated in the study. The subjects ran on a treadmill at three velocities (3.0, 3.5 and 4.0 m s-1) for 15 min each. The \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \({\dot{V}}_{\mathrm{O}_{2}}\) \end{document}consumption was measured by spirometry. At all three examined velocities the kinematics of the left leg were captured whilst running on the treadmill using a high-speed digital video camera operating at 250 Hz. Furthermore the runners performed isometric maximal voluntary plantarflexion and knee extension contractions at eleven different MTU lengths with their left leg on a dynamometer. The distal aponeuroses of the gastrocnemius medialis (GM) and vastus lateralis (VL) were visualised by ultrasound during plantarflexion and knee extension, respectively. The morphological properties of the GM and VL(fascicle length, angle of pennation, and thickness) were determined at three different lengths for each MTU. A cluster analysis was used to classify the subjects into three groups according to their \batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \({\dot{V}}_{\mathrm{O}_{2}}\) \end{document}consumption at all three velocities (high running economy, N=10;moderate running economy, N=12; low running economy, N=6). Neither the kinematic parameters nor the morphological properties of the GM and VL showed significant differences between groups. The most economical runners showed a higher contractile strength and a higher normalised tendon stiffness (relationship between tendon force and tendon strain) in the triceps surae MTU and a higher compliance of the quadriceps tendon and aponeurosis at low level tendon forces. It is suggested that at low level forces the more compliant quadriceps tendon and aponeurosis will increase the force potential of the muscle while running and therefore the volume of active muscle at a given force generation will decrease.

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“…(This ignores the effects of the muscle tendon which acts as a compliance in series with the muscle fibres. The relative compliance of the tendon compared to the muscle fibres determines the proportion of any over-all length change 'seen' by the muscle fibres and spindles (Rack & Westbury, 1984). It is likely that the tendons of the elbow flexors have a relatively low compliance so that most of the stretch is transmitted to the muscle fibres.…”

Section: Maintenance Of Position or Forcementioning

confidence: 99%

Maintenance of constant arm position or force: reflex and volitional components in man.

Colebatch

McCloskey

1987

The Journal of Physiology

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SUMMARY1. Normal subjects, with closed eyes, attempted to keep constant either the force exerted at the wrist or the position of the wrist against an elastic load. The load was attached to the wrist 275 mm from the axis of rotation of the elbow joint. During recording, the far end of the elastic load was displaced slowly enough that it was not immediately perceived but far enough for perception to occur before its completion.2. The over-all relation between wrist force and position for the two conditions was approximately linear and could be described in terms of effective stiffness. The effective stiffness for the constant-position task averaged 2-8 N/mm (210 N m/rad), while for the constant-force task the mean effective stiffness was -0-028 N/mm (-2 1 N m/rad), indicative of slight over-compensation.3. Averaging the performance at the onset of the imposed disturbance indicated that the subjects' behaviour consisted of two parts: an initial, small-range response followed by a second phase over the remainder of the displacement. The transition corresponded to the subjects' threshold for detection of the disturbance.4. The stiffness measured for the response prior to perception was taken as a measure which included the tonic stretch reflex. The stiffness was altered appropriately for the two tasks, being lower when the subjects tried to maintain the force exerted constant (average 1 1 N/mm, 83 N m/rad) than when they attempted to keep the position constant (average 2-3 N/mm, 170 N m/rad). A small degree of co-contraction occurred but could be dissociated from the stiffness changes.5. Scaling the results allowed comparison of the initial stiffness with values for the decerebrate cat. When analysed in this way, the values recorded in man during the constant-position task were similar to those reported for short-range stiffness in the decerebrate cat.6. The thresholds for detection of the disturbance were much lower than those reported for subjects with relaxed muscles.7. The stretch reflex in man has a direct role in compensating for small disturbances during motor tasks. It may also function to improve detection ofapplied disturbances by magnifying the corresponding force change. Once the stimulus is perceived and voluntary intervention is possible, a greater contrast is seen between the subjects' performance of the two tasks.

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Elastic properties of the cat soleus tendon and their functional importance.

Cited by 164 publications

References 25 publications

Passive mechanical properties of human gastrocnemius muscle–tendon units, muscle fascicles and tendonsin vivo

Passive mechanical properties of human gastrocnemius muscle–tendon units, muscle fascicles and tendonsin vivo

Influence of the muscle-tendon unit's mechanical and morphological properties on running economy

Maintenance of constant arm position or force: reflex and volitional components in man.

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