Perturbation measurements of papillary muscle elasticity

1981 ◽  
Vol 241 (2) ◽  
pp. H155-H173 ◽  
Author(s):  
A. J. Brady ◽  
S. T. Tan ◽  
N. V. Ricchiuti
Keyword(s):  
Mechanical Properties ◽  
Papillary Muscle ◽  
Muscle Length ◽  
Step Length ◽  
Muscle Stiffness ◽  
Force Measurements ◽  
Lumped Model ◽  
Isometric Twitch ◽  
Whole Muscle ◽  
Total Muscle

Small step-length perturbations (less than 0.5% Lmax) have been applied to rabbit papillary muscle for the purpose of measuring muscle stiffness at rest and during isometric twitch-force development. These stiffness-force measurements were fitted to four mechanical analogs to evaluate whether any of the models adequately predict the mechanical properties of papillary muscle. Stiffness-force relations have been measured at varied initial muscle lengths so that a broad range of applicability of an analog could be evaluated. This study shows that none of the four experimentally definable analogs predicts the stiffness-force responses of the muscle over a physiological range of initial muscle lengths. A two-segment nonhomogeneous analog has the same stiffness-force characteristics as a six-parameter lumped model but cannot be differentiated from the lumped model without a measurement of segmental variations. It is concluded that the passive elastic elements of papillary muscle cannot be controlled only by the manipulation of total muscle length so as to deduce cross-bridge mechanical properties from whole-muscle measurements.

scholarly journals PRACTICAL CONSIDERATIONS FOR STANDARDIZED RECORDING OF MUSCLE MECHANICAL PROPERTIES USING A MYOMETRIC DEVICE: RECORDING SITE, MUSCLE LENGTH, STATE OF CONTRACTION AND PRIOR ACTIVITY

2018 ◽  
Vol 21 (02) ◽  
pp. 1850010 ◽  
Author(s):  
Sandra Agyapong-Badu ◽  
Martin Warner ◽  
Dinesh Samuel ◽  
Maria Stokes
Keyword(s):  
Mechanical Properties ◽  
Biceps Brachii ◽  
Muscle Length ◽  
Rectus Femoris ◽  
Healthy Adults ◽  
Muscle Stiffness ◽  
Minimal Detectable Change ◽  
Experimental Conditions ◽  
Cross Sectional ◽  
Resting Muscle

Purpose: This study aimed to systematically examine the influence of various muscle and experimental conditions on Myoton recordings. Methods: A cross-sectional, observational design was used to examine muscle conditions and experimental factors (different recording sites, muscle length, level of contraction and prior physical activity) that may influence reproducibility of Myoton recordings for biceps brachii (BB) and rectus femoris (RF). Fifty-three healthy adults (26 young, 27 older) aged 18–90 years were studied. Muscle stiffness, tone and elasticity were measured using the MyotonPRO device. Results: Statistically significant differences in Myoton parameters were found for aspects of all four muscle and experimental conditions compared with the control condition ([Formula: see text]). However, clinically relevant differences in tone, stiffness and elasticity were only found for contracted compared to resting muscle, with changes being greater than the minimal detectable change. Elasticity was not affected by prior activity. Conclusions: The conditions studied significantly altered Myoton parameters of BB and RF in healthy adults, but only changes in parameters during muscle contraction were clinically relevant. These findings provide evidence to support the need to consider muscle condition and experimental factors for improving the robustness of test protocols for assessing muscle mechanical properties using the MyotonPRO device.

Nonuniform contraction in the isolated cat papillary muscle

1977 ◽  
Vol 233 (5) ◽  
pp. H613-H616 ◽  
Author(s):  
L. L. Huntsman ◽  
S. R. Day ◽  
D. K. Stewart
Keyword(s):  
Papillary Muscle ◽  
Video Recording ◽  
Muscle Length ◽  
Passive State ◽  
Papillary Muscles ◽  
Cat Papillary Muscle ◽  
Abrupt Transition ◽  
Mechanical Measurements ◽  
Center Region ◽  
Whole Muscle

Microspheres infused into the coronary microcirculation were used as markers to define segments within isolated cat papillary muscles. Video recording and analysis provided measurements of the variations of segment lengths as the muscles contracted at lengths of 76–100% Lmax. In all muscles, segments in the center region were found to shorten during muscle isometric contraction while those in the end regions lengthened. Central shortening was typically 10–15%. In the passive state, segment lengths varied directly with muscle length over a broad range characterized by low force. Segments in the center region, however, displayed an abrupt transition to high stiffness at a certain length while end regions continued to stretch. Force-length relationships obtained for the presumably healthy center segment are significantly different from those obtained for the whole muscle. These results suggest that there may be major difficulties with the interpretation of mechanical measurements on papillary muscles unless contractile inhomogeneity is eliminated or taken into account.

scholarly journals In vivo human gracilis whole muscle passive stress-sarcomere strain relationship

2021 ◽  
Author(s):  
Lomas S. Persad ◽  
Benjamin I. Binder-Markey ◽  
Alexander Y. Shin ◽  
Kenton R. Kaufman ◽  
Richard L. Lieber
Keyword(s):  
Mechanical Properties ◽  
Sarcomere Length ◽  
Mammalian Species ◽  
Muscle Length ◽  
Human Muscle ◽  
Gracilis Muscle ◽  
Rabbit Muscle ◽  
Cross Sectional ◽  
Whole Muscle

We measured the passive mechanical properties of intact, living human gracilis muscles (n=11 individuals, 1 female, age: 33±12years, mass: 89±23kg, height: 177±8cm). Measurements were performed in patients undergoing surgery for free functioning myocutaneous tissue transfer of the gracilis muscle to restore elbow flexion after brachial plexus injury. Whole muscle force of the gracilis tendon was measured in four joint configurations (JC1-JC4) with a buckle force transducer placed at the distal tendon. Sarcomere length was also measured by biopsy from the proximal gracilis muscle. After the muscle was removed a three-dimensional volumetric reconstruction of the muscle was created via photogrammetry. Muscle length from JC1 to JC4 increased by 3.3±1.0 cm, 7.7±1.2 cm, 10.5±1.3 cm and 13.4±1.2 cm respectively, corresponding to 15%, 34%, 46% and 59% muscle fiber strain respectively. Muscle volume and an average optimal fiber length of 23.1±0.7 cm yielded an average muscle physiological cross-sectional area of 6.8±0.7 cm2 which is approximately three times that measured previously from cadaveric specimens. Absolute passive tension increased from 0.90±0.21 N in JC1 to 16.50±2.64 N in JC4. As expected, sarcomere length also increased from 3.24±0.08 µm at JC1 to 3.63±0.07 µm at JC4, which are on the descending limb of the human sarcomere length-tension curve. Peak passive muscle stress was 27.8±5.5 kPa in JC4 and muscle modulus ranged from 44.8 MPa in JC1 to 125.7 MPa in JC4. Compared to other mammalian species, human muscle passive mechanical properties are more similar to rodent muscle than rabbit muscle. These data provide direct measurements of whole human muscle passive mechanical properties that can be used in modeling studies and for understanding comparative passive mechanical properties among mammalian muscles.

scholarly journals Instantaneous force-velocity-length relationship in diaphragmatic sarcomere

1997 ◽  
Vol 82 (2) ◽  
pp. 404-412 ◽  
Author(s):  
Catherine Coirault ◽  
Denis Chemla ◽  
Jean-Claude Pourny ◽  
Francine Lambert ◽  
Yves Lecarpentier
Keyword(s):  
Mechanical Properties ◽  
Striated Muscle ◽  
Mechanical Performance ◽  
Three Dimensional ◽  
Muscle Length ◽  
Total Load ◽  
Length Relationship ◽  
Abrupt Changes ◽  
Force Velocity ◽  
Isometric Twitch

Coirault, Catherine, Denis Chemla, Jean-Claude Pourny, Francine Lambert, and Yves Lecarpentier. Instantaneous force-velocity-length relationship in diaphragmatic sarcomere. J. Appl. Physiol. 82(2): 404–412, 1997.—The simultaneous analysis of muscle force, length, velocity, and time has been shown to precisely characterize the mechanical performance of isolated striated muscle. We tested the hypothesis that the three-dimensional force-velocity-length relationship reflects mechanical properties of sarcomeres. In hamster diaphragm strips, instantaneous sarcomere length (S L) and muscle length were simultaneously measured during afterloaded twitches. S L was measured by means of laser diffraction. We also studied the influence of initial S L, abrupt changes in total load, and 2 × 10−7 M dantrolene. Baseline resting S L at the apex of the length-active tension curve was 2.2 ± 0.1 μm, whereas S L at peak shortening was 1.6 ± 0.1 μm in the preloaded twitch and 2.1 ± 0.1 μm in the “isometric” twitch. Over the whole load continuum and at any given level of isotonic load, there was a unique relationship between instantaneous sarcomere velocity and instantaneous S L. Part of this relationship was time independent and initial S L independent and was markedly downshifted after dantrolene. When five different muscle regions were considered, there were no significant variations of S L and sarcomere kinetics along the muscle. These results indicate that the time- and initial length-independent part of the instantaneous force-velocity-length relationship previously described in muscle strips reflects intrinsic sarcomere mechanical properties.

Moderate-duration static stretch reduces active and passive plantar flexor moment but not Achilles tendon stiffness or active muscle length

2009 ◽  
Vol 106 (4) ◽  
pp. 1249-1256 ◽  
Author(s):  
Anthony D. Kay ◽  
Anthony J. Blazevich
Keyword(s):  
Mechanical Properties ◽  
Achilles Tendon ◽  
Muscle Stiffness ◽  
Triceps Surae ◽  
Medial Gastrocnemius ◽  
Static Stretch ◽  
Tendon Stiffness ◽  
Neuromuscular Activity ◽  
Time Motion ◽  
The Impact

The effects of static stretch on muscle and tendon mechanical properties and muscle activation were studied in fifteen healthy human volunteers. Peak active and passive moment data were recorded during plantar flexion trials on an isokinetic dynamometer. Electromyography (EMG) monitoring of the triceps surae muscles, real-time motion analysis of the lower leg, and ultrasound imaging of the Achilles-medial gastrocnemius muscle-tendon junction were simultaneously conducted. Subjects performed three 60-s static stretches before being retested 2 min and 30 min poststretch. There were three main findings in the present study. First, peak concentric moment was significantly reduced after stretch; 60% of the deficit recovered 30 min poststretch. This was accompanied by, and correlated with ( r = 0.81 ; P < 0.01) reductions in peak triceps surae EMG amplitude, which was fully recovered at 30 min poststretch. Second, Achilles tendon length was significantly shorter during the concentric contraction after stretch and at 30 min poststretch; however, no change in tendon stiffness was detected. Third, passive joint moment was significantly reduced after stretch, and this was accompanied by significant reductions in medial gastrocnemius passive muscle stiffness; both measures fully recovered by 30 min poststretch. These data indicate that the stretching protocol used in this study induced losses in concentric moment that were accompanied by, and related to, reductions in neuromuscular activity, but they were not associated with alterations in tendon stiffness or shorter muscle operating length. Reductions in passive moment were associated with reductions in muscle stiffness, whereas tendon mechanics were unaffected by the stretch. Importantly, the impact on mechanical properties and neuromuscular activity was minimal at 30 min poststretch.

The effects of pH on force and stiffness development in mouse muscles

1987 ◽  
Vol 65 (8) ◽  
pp. 1798-1801 ◽  
Author(s):  
J. M. Renaud ◽  
R. B. Stein ◽  
T. Gordon
Keyword(s):  
High Frequency ◽  
Small Amplitude ◽  
Force Production ◽  
Muscle Length ◽  
Low Ph ◽  
Muscle Stiffness ◽  
Average Force ◽  
Cross Bridge ◽  
Effects Of Ph ◽  
Cross Bridges

Changes in force and stiffness during contractions of mouse extensor digitorum longus and soleus muscles were measured over a range of extracellular pH from 6.4 to 7.4. Muscle stiffness was measured using small amplitude (<0.1% of muscle length), high frequency (1.5 kHz) oscillations in length. Twitch force was not significantly affected by changes in pH, but the peak force during repetitive stimulation (2, 3, and 20 pulses) was decreased significantly as the pH was reduced. Changes in muscle stiffness with pH were in the same direction, but smaller in extent. If the number of attached cross-bridges in the muscle can be determined from the measurement of small amplitude, high frequency muscle stiffness, then these findings suggest that (a) the number of cross-bridges between thick and thin filaments declines in low pH and (b) the average force per cross-bridge also declines in low pH. The decline in force per cross-bridge could arise from a reduction in the ability of cross-bridges to generate force during their state of active force production and (or) in an increased percentage of bonds in a low force, "rigor" state.

Effects of myostatin on the mechanical properties of muscles during repeated active lengthening in the mouse

2019 ◽  
Vol 44 (4) ◽  
pp. 381-388
Author(s):  
Danguole Satkunskiene ◽  
Aivaras Ratkevicius ◽  
Sigitas Kamandulis ◽  
Tomas Venckunas
Keyword(s):  
Mechanical Properties ◽  
Isometric Force ◽  
Muscle Stiffness ◽  
Repeated Loading ◽  
Relative Reduction ◽  
Muscle Type ◽  
Age Dependent ◽  
Exercise Induced ◽  
Edl Muscle ◽  
Early Phases

The aim of the present study was to investigate how myostatin dysfunction affects fast and slow muscle stiffness and viscosity during severe repeated loading. Isolated extensor digitorum longus (EDL) and soleus muscles of young adult female mice of the BEH (dysfunctional myostatin) and BEH+/+ (functional myostatin) strains were subjected to 100 contraction–stretching loading cycles during which contractile and mechanical properties were assessed. BEH mice exhibited greater exercise-induced muscle damage, although the effect was muscle- and age-dependent and limited to the early phases of simulated exercise. The relative reduction of the EDL muscle isometric force recorded during the initial 10–30 loading cycles was greater in BEH mice than in BEH+/+ mice and exceeded that of the soleus muscle of either strain. The induced damage was associated with lower muscle stiffness. The effects of myostatin on the mechanical properties of muscles depend on muscle type and maturity.

Dependence of energy output on force generation during muscle contraction

1978 ◽  
Vol 235 (1) ◽  
pp. C20-C24 ◽  
Author(s):  
J. A. Rall
Keyword(s):  
Muscle Length ◽  
Maximum Velocity ◽  
Force Generation ◽  
Energy Output ◽  
Energy Liberation ◽  
Work Output ◽  
Extra Energy ◽  
Constant Distance ◽  
The Difference ◽  
Isometric Twitch

It has been proposed that the energy (heat + work) output of an isometric twitch is determined by the force that is generated under conditions of invariant activation, irrespective of muscle length. To test the effect of length and force on total energy output, muscles were stretched by increments beyond the muscle length at which twitch force is maximum (LO) and then stimulated; energy output and force then were measured. These data were compared with isovelocity twitches in which stimulated muscles, initially at different lengths, shortened (near maximum velocity) a constant distance and then redeveloped tension at lengths less than LO. If energy liberation was determined by force generation, plots of energy output versus force produced would be parallel with isovelocity twitches liberating extra energy as shortening heat. As predicted, the ratio of the slopes (n = 13) of these relations, 0.98 +/- 0.02, was not different from 1 and the shortening heat coefficient (alphaF/Pot, measured from the difference in intercepts), 0.15 +/- 0.01, was near to the expected value. Therefore, energy liberation in twitches appears to be uniquely determined by force generation and not by muscle length.

scholarly journals The influence of training-induced sarcomerogenesis on the history dependence of force

2020 ◽  
Vol 223 (15) ◽  
pp. jeb218776 ◽  
Author(s):  
Jackey Chen ◽  
Parastoo Mashouri ◽  
Stephanie Fontyn ◽  
Mikella Valvano ◽  
Shakeap Elliott-Mohamed ◽  
...  
Keyword(s):  
Extensor Digitorum Longus ◽  
Isometric Force ◽  
Muscle Length ◽  
Force Enhancement ◽  
Active Muscle ◽  
Training Groups ◽  
Force Depression ◽  
Residual Force ◽  
Residual Force Enhancement ◽  
Whole Muscle

ABSTRACTThe increase or decrease in isometric force following active muscle lengthening or shortening, relative to a reference isometric contraction at the same muscle length and level of activation, are referred to as residual force enhancement (rFE) and residual force depression (rFD), respectively. The purpose of these experiments was to investigate the trainability of rFE and rFD on the basis of serial sarcomere number (SSN) alterations to history-dependent force properties. Maximal rFE/rFD measures from the soleus and extensor digitorum longus (EDL) of rats were compared after 4 weeks of uphill or downhill running with a no-running control. SSN adapted to the training: soleus SSN was greater with downhill compared with uphill running, while EDL demonstrated a trend towards more SSN for downhill compared with no running. In contrast, rFE and rFD did not differ across training groups for either muscle. As such, it appears that training-induced SSN adaptations do not modify rFE or rFD at the whole-muscle level.

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