The potentiating effect of prestretch on the contractile performance of rat gastrocnemius medialis muscle during subsequent shortening and isometric contractions

1992 ◽  
Vol 165 (1) ◽  
pp. 121-136 ◽  
Author(s):  
G. J. Ettema ◽  
P. A. Huijing ◽  
A. de Haan
Keyword(s):  
Muscle Length ◽  
Dynamic Responses ◽  
Muscle Performance ◽  
Muscle Fibres ◽  
Isometric Contractions ◽  
Shortening Velocity ◽  
Average Force ◽  
Gastrocnemius Medialis ◽  
Dynamic Experiments ◽  
Length Changes

The aim of the present study was to investigate the effect of an active stretch during the onset of a muscle contraction on subsequent active behaviour of the contractile machinery within an intact mammalian muscle-tendon complex. Muscle length and shortening velocity were studied because they may be important variables affecting this so-called prestretch effect. Seven gastrocnemius medialis (GM) muscles of the rat were examined. Tetanic, isovelocity shortening contractions from 3 mm above muscle optimum length (l0) to l0 - 2 mm, at velocities of 10–50 mm s-1 (dynamic experiments), were preceded by either an isometric contraction (PI) or an active stretch (PS). By imposing quick length decreases between the prephase and the concentric phase, all excess force generated in the prephase was instantaneously eliminated. This procedure only allowed small force changes during subsequent shortening (caused by the intrinsic properties of the contractile machinery). In this way, the influence of series elastic structures on subsequent muscle performance was minimized. Experiments were also performed at lengths ranging from l0 + 2.5 mm to l0 - 1.5 mm, keeping the length constant after the initial quick length changes (isometric experiments). For the dynamic experiments, enhancement of the performance of the contractile machinery (potentiation) was calculated as the ratio of the average force level over each millimetre of shortening during PS to that during PI conditions (PS/PI). For the isometric experiments, the PS/PI force ratio after 300 ms of stimulation was used. The main result of the present study confirmed results reported in the literature and experiments on isolated muscle fibres. For all conditions, a potentiation effect was found, ranging from about 2 to 16%. Muscle length appeared to have a large positive effect on the degree of potentiation. At the greatest lengths potentiation was largest, but at lengths below optimum a small effect was also found. A negative influence of shortening velocity was mainly present at increased muscle lengths (l0 + 2.5 mm and l0 + 1.5 mm). For the dynamic experiments, no interaction was found between the effects of muscle length and shortening velocity on potentiation. However, there was a clear difference between the isometric and dynamic responses: the dependence of potentiation on muscle length was significantly greater for the isometric contractions than for the dynamic ones. These isometric-dynamic differences indicate that the processes underlying prestretch effects operate differently under isometric and dynamic conditions.(ABSTRACT TRUNCATED AT 400 WORDS)

MUSCLE BULGING REDUCES MUSCLE FORCE AND LIMITS THE MAXIMAL EFFECTIVE MUSCLE SIZE

2006 ◽  
Vol 06 (03) ◽  
pp. 229-239 ◽  
Author(s):  
KARL DAGGFELDT
Keyword(s):  
Muscle Force ◽  
Muscle Length ◽  
Biomechanical Model ◽  
Muscle Performance ◽  
Muscle Size ◽  
Intramuscular Pressure ◽  
Shortening Velocity ◽  
Muscle Shortening ◽  
Force Reduction ◽  
Total Muscle

A biomechanical model was generated in order to investigate the possible mechanisms behind reductions in muscle performance due to muscle bulging. It was shown that the proportion of fiber force contributing to the total muscle force is reduced with fiber bulging and that the cause of this reduction is due to the intramuscular pressure (IMP) created by the bulging fibers. Moreover, it was established that the amount of IMP generated muscle force reduction is determined by the extent to which muscle thickening restricts muscle fibers from shortening, thereby limiting their power contribution. It was shown that bulging can set a limit to the maximal size a muscle can take without losing force and power producing capability. Possible effects, due to bulging, on maximal muscle force in relation to both muscle length and muscle shortening velocity were also demonstrated by the model.

scholarly journals Three-dimensional geometrical changes of the human tibialis anterior muscle and its central aponeurosis measured with three-dimensional ultrasound during isometric contractions

PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e2260 ◽  
Author(s):  
Brent J. Raiteri ◽  
Andrew G. Cresswell ◽  
Glen A. Lichtwark
Keyword(s):  
Three Dimensional ◽  
Muscle Length ◽  
Pennation Angle ◽  
Human Muscle ◽  
Muscle Fibres ◽  
Isometric Contractions ◽  
Fascicle Length ◽  
Cross Sectional ◽  
Shape Changes

Background.Muscles not only shorten during contraction to perform mechanical work, but they also bulge radially because of the isovolumetric constraint on muscle fibres. Muscle bulging may have important implications for muscle performance, however quantifying three-dimensional (3D) muscle shape changes in human muscle is problematic because of difficulties with sustaining contractions for the duration of anin vivoscan. Although two-dimensional ultrasound imaging is useful for measuring local muscle deformations, assumptions must be made about global muscle shape changes, which could lead to errors in fully understanding the mechanical behaviour of muscle and its surrounding connective tissues, such as aponeurosis. Therefore, the aims of this investigation were (a) to determine the intra-session reliability of a novel 3D ultrasound (3DUS) imaging method for measuringin vivohuman muscle and aponeurosis deformations and (b) to examine how contraction intensity influencesin vivohuman muscle and aponeurosis strains during isometric contractions.Methods.Participants (n= 12) were seated in a reclined position with their left knee extended and ankle at 90° and performed isometric dorsiflexion contractions up to 50% of maximal voluntary contraction. 3DUS scans of the tibialis anterior (TA) muscle belly were performed during the contractions and at rest to assess muscle volume, muscle length, muscle cross-sectional area, muscle thickness and width, fascicle length and pennation angle, and central aponeurosis width and length. The 3DUS scan involved synchronous B-mode ultrasound imaging and 3D motion capture of the position and orientation of the ultrasound transducer, while successive cross-sectional slices were captured by sweeping the transducer along the muscle.Results.3DUS was shown to be highly reliable across measures of muscle volume, muscle length, fascicle length and central aponeurosis length (ICC ≥ 0.98, CV < 1%). The TA remained isovolumetric across contraction conditions and progressively shortened along its line of action as contraction intensity increased. This caused the muscle to bulge centrally, predominantly in thickness, while muscle fascicles shortened and pennation angle increased as a function of contraction intensity. This resulted in central aponeurosis strains in both the transverse and longitudinal directions increasing with contraction intensity.Discussion.3DUS is a reliable and viable method for quantifying multidirectional muscle and aponeurosis strains during isometric contractions within the same session. Contracting muscle fibres do work in directions along and orthogonal to the muscle’s line of action and central aponeurosis length and width appear to be a function of muscle fascicle shortening and transverse expansion of the muscle fibres, which is dependent on contraction intensity. How factors other than muscle force change the elastic mechanical behaviour of the aponeurosis requires further investigation.

IN VIVO MUSCLE LENGTH CHANGES IN BUMBLEBEES AND THE IN VITRO EFFECTS ON WORK AND POWER

1993 ◽  
Vol 183 (1) ◽  
pp. 101-113 ◽  
Author(s):  
K. M. Gilmour ◽  
C. P. Ellington
Keyword(s):  
High Speed ◽  
Time Course ◽  
Second Harmonic ◽  
Muscle Length ◽  
Muscle Fibres ◽  
Bombus Lucorum ◽  
Length Changes ◽  
In Vitro Effects

The amplitude and time course of muscle length changes were examined in vivo in tethered, flying bumblebees Bombus lucorum. A ‘window’ was cut in the dorsal cuticle and aluminium particles were placed on the exposed dorsal longitudinal muscle fibres. Muscle oscillations were recorded using high-speed video and a high-magnification lens. The amplitude of muscle length changes was 1.9 % (s.d.=0.5 %, N=7), corresponding to the commonly quoted strain of 1–3 % for asynchronous muscle. Higher harmonics, particularly the second, were found in the muscle oscillations and in the wing movements. The second harmonic for wing movements was damped in comparison to that for muscle length changes, probably as a result of compliance in the thoracic linkage. Inclusion of the second harmonic in the driving signal for in vitro experiments on glycerinated fibres generally resulted in a decrease in the work and power, but a substantial increase was found for some fibres.

Length Range, Morphology and Mechanical Behaviour of Rat Gastrocnemius Muscle During Isometric Contraction At the Level of the Muscle and Muscle Tendon Complex

1984 ◽  
Vol 35 (3) ◽  
pp. 505-516 ◽  
Author(s):  
R.D. Woittiez ◽  
P.A. Huijing
Keyword(s):  
Isometric Contraction ◽  
Fibre Length ◽  
Muscle Length ◽  
Muscle Fibres ◽  
Isometric Contractions ◽  
Force Relation ◽  
Length Range ◽  
Equilibrium Length ◽  
Fibre Angle

Fibre length, fibre angle and muscle length were quantified for rat m. gastrocnemius medialis with the muscle passive as well as fully activated during isometric contraction. This was done with the muscle in situ still attached with intact origin and insertion as well as with the calcaneus cut for simultaneous force measurements. Comparison of muscle lengths in maximal plantar and dorsal flexion with the physiological length range of the muscle, as defined by the limits of the length force relation, indicated that approximately the lower 75% of this range may be used between the extreme ankle angles, while the knee is kept at 90° of flexion. It is likely that simultaneous knee extentension would take the muscle through the remainder of its physiological length range. During isometric contractions at the level of the muscle, fibres shorten and fibre angles increase (with values exceeding 12 % and 45 % respectively at short muscle lengths). At short lengths fibre angle may reach values exceeding 40°, thereby creating sizable differences between force exerted by the muscle and that of its fibres. Changes of fibre length and fibre angle increase with decreasing muscle length and are ascribed to compliance effects of the aponeuroses above muscle equilibrium length while below muscle equilibrium length a taking up of slack present in these structures occurs prior to these compliance effects. During isometric contractions at the level of the muscle-tendon complex work will be performed by the muscle on the achilles tendon. This work was estimated from tendon length-force characteristics. Its peak value does not exceed 1.35 mJ for any of the muscles at anv length, which is small ( < 2 % ) relative to estimated total energv expenditure of the isometric contractions.

scholarly journals Variation of muscle stiffness with force at increasing speeds of shortening.

1975 ◽  
Vol 66 (3) ◽  
pp. 287-302 ◽  
Author(s):  
F J Julian ◽  
M R Sollins
Keyword(s):  
High Frequency ◽  
Muscle Length ◽  
Maximum Velocity ◽  
Specific Model ◽  
Muscle Stiffness ◽  
Force Balance ◽  
Shortening Velocity ◽  
Velocity Of Shortening ◽  
Length Changes ◽  
Cross Bridges

Single frog skeletal muscle fibers were attached to a servo motor and force transducer by knotting the tendons to pieces of wire at the fiver insertions. Small amplitude, high frequency sinusoidal length changes were then applied during tetani while fibers contracted both isometrically and isotonically at various constant velocities. The amlitude of the resulting force oscillation provides a relative measure of muscle stiffness. It is shown from an analysis of the transient force responses observed after sudden changes in muscle length applied both at full and reduced overlap and during the rising phase of short tetani that these responses can be explained on the basis of varying numbers of cross bridges attached at the time of the length step. Therefore, the stiffness measured by the high frequency legth oscillation method is taken to be directly proportional to the number of cross bridges attached to thin filament sittes. It is found that muscle stiffness measured in this way falls with increasing shortening velocity, but not as rapidly as the force. The results suggest that at the maximum velocity of shortening, when the external force is zero, muscle stiffness is still substantial. The findings are interpreted in terms of a specific model for muscle contraction in which the maximum velocity of shortening under zero external load arises when a force balance is attained between attached cross bridges somr interpretations of these results are also discussed.

Load, length, and velocity of load-moving tibialis anterior muscle of the cat

1996 ◽  
Vol 80 (6) ◽  
pp. 2243-2249 ◽  
Author(s):  
R. V. Baratta ◽  
M. Solomonow ◽  
G. Nguyen ◽  
R. D'Ambrosia
Keyword(s):  
Tibialis Anterior ◽  
Tibialis Anterior Muscle ◽  
Three Dimensional ◽  
Muscle Length ◽  
Muscle Performance ◽  
Maximal Velocity ◽  
Load Spectrum ◽  
Velocity Of Shortening ◽  
Length Changes ◽  
Nerve Recordings

Three-dimensional relationships of load, length, and velocity of shortening of the tibialis anterior muscle in the cat were derived experimentally and fitted with an analytic model. Gravitational loads were applied to the isolated muscle, which arrived at an equilibrium with the passive forces before supramaximal tetanic stimulation was delivered to its nerve. Recordings of initial passive muscle length at equilibrium and length changes throughout the shortening phase up to the final length at active equilibrium were taken and numerically differentiated to obtain each load's instantaneous velocity. A three-dimensional surface was constructed by using instantaneous length and the corresponding velocity for each of several loads. Maximal velocity of shortening was shown to gradually decrease, occurring earlier in the shortening phase (at larger muscle lengths) as loads increased. Whereas load-velocity curves were hyperbolic for middle and short muscle lengths, they were nonmonotonic during shortening above the optimal length. The model was found to correlate well with the experimental data (R = 0.98) and allowed for prediction of both muscle performance boundaries and instantaneous shortening velocity for a given length across the physiological load spectrum, thus offering a realistic estimation of the contractile properties exhibited by the tibialis anterior muscle in functions similar to naturally occurring movements against gravitational loads, which are accelerated and decelerated during the movement.

BODY SIZE, MUSCLE POWER OUTPUT AND LIMITATIONS ON BURST LOCOMOTOR PERFORMANCE IN THE LIZARD DIPSOSAURUS DORSALIS

1993 ◽  
Vol 174 (1) ◽  
pp. 199-213 ◽  
Author(s):  
T. P. Johnson ◽  
S. J. Swoap ◽  
A. F. Bennett ◽  
R. K. Josephson
Keyword(s):  
Body Size ◽  
Body Mass ◽  
Power Output ◽  
Muscle Power ◽  
Muscle Length ◽  
Muscle Fibres ◽  
Dipsosaurus Dorsalis ◽  
Cycling Frequency ◽  
Length Changes

The power output of fast-glycolytic (FG) muscle fibres isolated from the iliofibularis (IF) muscle of desert iguanas (Dipsosaurus dorsalis) was measured at 35 sC using the oscillatory work-loop technique. To simulate cyclical muscle length changes during running, isolated fibre bundles were subjected to sinusoidal length changes and phasic stimulation during the strain cycle. At constant strain (12 %), the duration and timing (phase) of stimulation were adjusted to maximise power output. Using both hatchlings (4–8 g) and adults of varying sizes (15–70 g), the intraspecific allometries of IF length and contractile properties were described by regression analysis. The muscle length at which isometric force was maximum (L0, mm) increased geometrically with body mass (M, g) (L0=5.7M0.33). Maximum power output and the force produced during shortening showed no significant relationship to body size; work output per cycle (Wopt, J kg-1) under conditions required to maximise power did increase with body size (Wopt=3.7M0.24). Twitch duration (Td, ms), measured from the onset of force generation to 50 % relaxation, increased allometrically with body mass (Td=12.4M0.18). Limb cycling frequency during burst running (f, reported in the literature) and the frequency required to maximise power output in vitro (fopt) decreased with body size, both being proportional to body mass raised to the power 0.24. These findings suggest that limb cycling frequency may be limited by twitch contraction kinetics. However, despite corresponding proportionality to body size, limb cycling frequencies during burst running are about 20 % lower than the cycling frequencies required to maximise power output. Differences in the contractile performance of the IF in vitro and in vivo are discussed in relation to constraints imposed by gravitational forces and the design of muscular, nervous and skeletal systems.

Influence of submaximal isometric contractions of the hamstrings on electromyography activity and force while functioning as hip extensors

2020 ◽  
pp. 1-8
Author(s):  
Dasom Oh ◽  
Wootaek Lim
Keyword(s):  
Prone Position ◽  
Supine Position ◽  
Isometric Contraction ◽  
Muscle Length ◽  
Biceps Femoris ◽  
Emg Activity ◽  
Isometric Contractions ◽  
Significant Difference ◽  
Extension Force ◽  
Long Head

BACKGROUND: Although the medial and lateral hamstrings are clearly distinct anatomically and have different functions in the transverse plane, they are often considered as one muscle during rehabilitation. OBJECTIVE: The purpose of the study was to compare the electromyographic (EMG) activity between the prone position and the supine position during maximal isometric contraction and to additionally confirm the effect of submaximal isometric contractions on EMG activity of medial and lateral hamstrings, and force. METHODS: In the prone position, EMG activities of the long head of biceps femoris (BFLH) and semitendinosus (ST) were measured during the maximal isometric contraction. In the supine position, hip extension force with EMG activity were measured during the maximal and the submaximal isometric contractions. RESULTS: EMG activity in the prone position was significantly decreased in the supine position. In the supine position, there was a significant difference between the BFLH and ST during the maximal isometric contraction, but not during the submaximal isometric contractions. CONCLUSIONS: The dependence on the hamstrings could be relatively lower during hip extensions. When the medial and lateral hamstrings are considered separately, the lateral hamstrings may show a more active response, with increased muscle length, in clinical practice.

Heat production of rat anococcygeus muscle during isometric contraction

1988 ◽  
Vol 255 (4) ◽  
pp. C536-C542 ◽  
Author(s):  
J. S. Walker ◽  
I. R. Wendt ◽  
C. L. Gibbs
Keyword(s):  
Energy Expenditure ◽  
Heat Production ◽  
Progressive Increase ◽  
Isometric Contractions ◽  
Shortening Velocity ◽  
Anococcygeus Muscle ◽  
Cross Bridge ◽  
Time Integral ◽  
Rat Anococcygeus Muscle ◽  
Cross Bridges

Heat production, unloaded shortening velocity (Vus), and load-bearing capacity (LBC) were studied in the isolated rat anococcygeus muscle during isometric contractions at 27 degrees C. The relation between the total suprabasal heat produced and the stress-time integral for isometric contractions of various durations was curvilinear, demonstrating a decreasing slope as contractile duration increased. The rate of heat production at 600 s was approximately 68% of the peak value of 6.55 mW/g that occurred at 10 s. At the same time, force rose from a mean of 92 mN/mm2 at 10 s to a value of 140 mN/mm2 at 600 s. This produced a nearly threefold increase in the economy of force maintenance. The decline in the rate of heat production was accompanied by a decline in Vus from 0.56 Lo/s at 10 s to 0.28 Lo/s at 600 s, where Lo is the length for optimal force development. This suggests the fall in the rate of heat production was caused, at least in part, by a slowing of cross-bridge kinetics. The ratio of LBC to developed tension at 10 s was not significantly different from the ratio at 600 s, suggesting that the increase in tension was due to an increased number of attached cross bridges. The decline in heat production, therefore, appears contradictory, since an increased number of attached cross bridges would predict an increased rate of energy expenditure. The observations can be reconciled if either 1) the increase in force is caused by a progressive increase in the attachment time of a constant number of cross bridges that cycle at a lower frequency or 2) the decline in energy expenditure caused by the slowing of cross-bridge cycling is sufficient to mask the increase caused by the recruitment of additional cross bridges.

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