The force-velocity properties of a crustacean muscle during lengthening

1999 ◽  
Vol 202 (5) ◽  
pp. 593-607 ◽  
Author(s):  
R.K. Josephson ◽  
D.R. Stokes
Keyword(s):  
Time Constant ◽  
Constant Velocity ◽  
Muscle Activation ◽  
Isometric Force ◽  
Carcinus Maenas ◽  
Stimulus Frequency ◽  
Isometric Tension ◽  
Low Velocity ◽  
Force Increase ◽  
Force Velocity

Muscle force during active lengthening was characterized for scaphognathite levator muscle L2B from the crab Carcinus maenas. The muscle was tetanically stimulated and, during the peak of the contraction, stretched at constant velocity. The total strain was approximately 4 %, the strain rates ranged from 0.03 to 1.6 muscle lengths s-1 (L s-1), and the temperature was 15 degreesC. Force increased throughout stretch. During low-velocity stretch, up to approximately 0.3 L s-1, force rose during isovelocity stretch along an approximately exponential trajectory. The asymptotic force approached during the stretch increased and the time constant of the response decreased with increasing strain rate. With stretch at 0.6 L s-1 and greater, the force increased to a distinct yield point, reached after a strain of approximately 1 %, after which force continued to increase but with a slope approximately one-quarter as great as that before yield. Because force changes continuously during constant-velocity lengthening, the adequate descriptor for the force-velocity relationship in a lengthening crab muscle is not a two-dimensional force-velocity curve, but rather a three-dimensional force-velocity-time or force-velocity-strain surface. Stimulating muscle L2B at 20 Hz or 50 Hz gives a smoothly fused tetanic contraction in which muscle activation is only partial and the plateau force reached is less than that at the optimum stimulus frequency of approximately 100 Hz. The force-velocity relationships of a partially activated muscle are not simply those of a fully activated one scaled down in proportion to the reduction in the maximum isometric force. At low stretch velocities, the asymptotic force approached is larger in proportion to the pre-stretch isometric tension, and the time constant of the force increase is greater, in partially activated than in fully activated muscles. At high stretch velocities, the force at yield relative to the pre-stretch force, and the relative values of the slopes of the force increase before and after yield, are all greater in partially activated than in fully activated muscles, while the strain at yield is smaller.

Work-dependent deactivation of a crustacean muscle

1999 ◽  
Vol 202 (18) ◽  
pp. 2551-2565 ◽  
Author(s):  
R.K. Josephson ◽  
D.R. Stokes
Keyword(s):  
Muscle Activation ◽  
Isometric Force ◽  
Carcinus Maenas ◽  
Stimulus Frequency ◽  
Force Production ◽  
Muscle Length ◽  
Background Level ◽  
Shortening Velocity ◽  
Shortening Deactivation ◽  
Work Done

Active shortening of respiratory muscle L2B from the crab Carcinus maenas results in contractile deactivation, seen as (1) a decline of force during the course of isovelocity shortening, (2) a reduction in the rate of force redevelopment following shortening, (3) a depression of the level of isometric force reached following shortening, and (4) an accelerated relaxation at the end of stimulation. The degree of deactivation increases with increasing distance of shortening, decreases with increasing shortening velocity, and is approximately linearly related to the work done during shortening. Deactivation lasts many seconds if stimulation is maintained, but is largely although not completely removed if the stimulation is temporarily interrupted so that the force drops towards the resting level. Deactivation for a given distance and velocity of shortening increases with increasing muscle length above the optimum length for force production. Stimulating muscle L2B at suboptimal frequencies gives tetanic contractions that are fully fused but of less than maximal amplitude. The depression of force following shortening, relative to the force during an isometric contraction, is independent of the stimulus frequency used to activate the muscle, indicating that deactivation is not a function of the background level of stimulus-controlled muscle activation upon which it occurs. Deactivation reduces the work required to restretch a muscle after it has shortened, but it also lowers the force and therefore the work done during shortening. The net effect of deactivation on work output over a full shortening/lengthening cycle is unknown.

scholarly journals The Contractile Properties of a Crab Respiratory Muscle

1987 ◽  
Vol 131 (1) ◽  
pp. 265-287 ◽  
Author(s):  
ROBERT K. JOSEPHSON ◽  
DARRELL R. STOKES
Keyword(s):  
Carcinus Maenas ◽  
Stimulus Frequency ◽  
Muscle Length ◽  
Isometric Tension ◽  
Shortening Velocity ◽  
Force Velocity ◽  
Contraction And Relaxation ◽  
Full Activation ◽  
Stimulus Number

1. Contraction of scaphognathite muscle L2B of the green crab Carcinus maenas is strongly dependent on stimulus number and frequency. Single, supramaximal stimuli evoke little or no tension. When stimulated with shocks in either short bursts (10 stimuli in 0.5s or less) or long bursts (5 s of stimulation), the isometric tension from the muscle increases with increasing stimulus frequency to a maximum at about 150 Hz at 15°C, beyond which tension declines with further increase in stimulus frequency. 2. There can be facilitation of both contraction and relaxation between short bursts of stimuli. Facilitation of contraction is seen as increasing tension on successive bursts of a series, even when the interburst interval is long enough for relaxation to be completed during the interval. Interburst facilitation lasts at least 10 s. Facilitation of relaxation is seen as progressively faster relaxation from burst to burst of a series, and relaxation to lower tension levels when the interburst interval is so short that relaxation is incomplete in the interburst interval. 3. Maximum isometric tension occurs at muscle lengths slightly longer than the longest muscle length reached in vivo. Tension declines rapidly with changes in muscle length away from the optimum length. The maximum isometric tension was about 12 N cm−2. 4. The maximum shortening velocity of a tetanically activated muscle was determined as 1.9 lengthss−1 (Ls−1) by extrapolation of force-velocity curves to zero force and 3.3 Ls−1 by slack test measurements. 5. The scaphognathite muscle would be classified as a slow or tonic muscle on the basis of its requirements for multiple stimulation to reach full activation, and as a moderately fast muscle on the basis of its force-velocity properties.

CONTRACTILE PROPERTIES OF A HIGH-FREQUENCY MUSCLE FROM A CRUSTACEAN - CONTRACTION KINETICS

1994 ◽  
Vol 187 (1) ◽  
pp. 275-293 ◽  
Author(s):  
D Stokes ◽  
R Josephson
Keyword(s):  
High Frequency ◽  
Isometric Force ◽  
Carcinus Maenas ◽  
Stimulus Frequency ◽  
Length Change ◽  
Shortening Velocity ◽  
Long Duration ◽  
Maximum Isometric Force ◽  
Small Muscle

1. The flagella (small appendages on the maxillipeds) of the crab Carcinus maenas beat regularly when active at about 10 Hz (15 °C). The beat of a flagellum is due to contraction of a single small muscle, the flagellum abductor (FA). The optimal stimulus frequency for tetanic contraction of the FA was about 200 Hz. When the muscle was stimulated at 10 Hz with paired stimuli per cycle, the interstimulus interval that maximized peak force was 2­4 ms, which corresponded well to the interspike intervals within bursts recorded from motor axons during normal beating. 2. Contraction of the isolated FA showed pronounced neuromuscular facilitation and many stimuli were needed to activate the muscle fully. The dependence on facilitation in isolated muscles appeared to be greater than that in vivo. It is suggested that neuromodulators in the blood of the crab enhance neuromuscular transmission and reduce the dependency on facilitation in intact animals. 3. The FA had a narrow length­tension curve. Tetanic tension became vanishingly small at muscle lengths less than about 90 % of the maximum in vivo length. The maximum length change of the muscle during in vivo contraction was about 5 %. 4. The maximum isometric force of the FA was low (about 6 N cm-2) but its shortening velocity was high. Vm, the maximum shortening velocity determined from isotonic shortening, was 4.0 muscle lengths s-1; V0, the maximum shortening velocity from slack test measurements, was about 8 lengths s-1. 5. The structure and physiology of the FA are compared with those of locust flight muscle, chosen because it too is a muscle capable of long-duration, high-frequency performance.

Graded activation in rabbit mesotubarium smooth muscle

1975 ◽  
Vol 229 (2) ◽  
pp. 455-465 ◽  
Author(s):  
RA Meiss
Keyword(s):  
Smooth Muscle ◽  
Phase Plane ◽  
Isometric Force ◽  
Stimulus Frequency ◽  
Hill Equation ◽  
Electrical Field ◽  
First Derivative ◽  
Force Velocity ◽  
The Hill ◽  
Slow Onset

The outer margin of the mesotubarium superius, an accessory ligament from the femal rabbit reproductive system, contains a long and slender bundle of smooth muscle fibers well aligned with the long axis of the tissue. Very little connective tissue is present. Massive alternating-current electrical field stimuli (variable in frequency, amplitude, and duration) applied to isolated mesotubaria from mature, nonpregnant animals produced contractions in which isometric force (P) and its first derivative (dP/dt) could be continuously graded; an optimum existed for stimulus frequency and amplitude, but not for its duration. Twitchlike contractions could not be produced. Isometric contractions in which P was plotted against dP/dt to generate a phase-plane trajectory were used to predict the ultimate (time = infinity) force (Po) in graded contractions; this value agreed with the Po derived from isotonic force-velocity curves fitted to the Hill equation. Quick stretches applied during the rise of contractile force revealed a slow onset of the ability to bear the Po force.

Mechanics of stretch in activated crustacean slow muscle. I. Factors affecting peak force

1989 ◽  
Vol 62 (5) ◽  
pp. 997-1005 ◽  
Author(s):  
W. D. Chapple
Keyword(s):  
Muscle Activation ◽  
Isometric Force ◽  
Motor Units ◽  
Abdominal Muscle ◽  
Isometric Tension ◽  
Peak Force ◽  
Factors Affecting ◽  
Pooled Data ◽  
Passive Stretch ◽  
The Relationship

1. The active stiffness of ventral superficial abdominal muscle (VSM) of the hermit crab, Pagurus pollicarus, was measured with ramp stretches of different amplitudes and velocities. Active stiffness was calculated by subtracting the peak force produced by passive stretch and the isometric force just before stretch from the peak force produced by stretching active muscle. The result was then divided by stretch length to give stiffness. 2. The relationship between force just before stretch (the level of activation) and active stiffness was curvilinear and was found to apply under a variety of experiment conditions. For pooled data from eight experiments, active stiffness (GN.m-2.m-1) = 3.2*stress (MN/m2)-7.6*stress2. Decreasing the number of motor units or activating the inhibitor did not alter this relationship nor did the addition of proctolin, octopamine, or 5-HT to the bath. The relationship also applied during the rising phase of isometric tension. However, stiffness declined more rapidly than predicted by this relationship after the end of tetanus. 3. Active stiffness varied inversely with stretch amplitude for fast stretches, and the slope of this relationship increased with increasing muscle activation. At lower stretch velocities, the slope was much less than at rapid stretch velocities, so at low levels of activation and stretch velocity, active stiffness was essentially independent of stretch length. 4. Active stiffness covaried with muscle force as both were sampled at shorter and shorter lengths on the ascending limb of the length-tension curve.(ABSTRACT TRUNCATED AT 250 WORDS)

A modified force-velocity equation for smooth muscle contraction

1994 ◽  
Vol 76 (1) ◽  
pp. 253-258 ◽  
Author(s):  
J. Wang ◽  
H. Jiang ◽  
N. L. Stephens
Keyword(s):  
Smooth Muscle ◽  
Isometric Force ◽  
Smooth Muscle Contraction ◽  
Tracheal Smooth Muscle ◽  
Low Velocity ◽  
Hill’S Equation ◽  
Quick Release ◽  
Hill's Equation ◽  
Data Points ◽  
Force Velocity

It has been suggested that in skeletal muscle the force-velocity relationship may not be a simple hyperbolic one, as defined by Hill's equation. To determine whether smooth muscle demonstrated the same properties, quick-release force-velocity curves were obtained from canine tracheal smooth muscle. The results showed that the observed data points for tracheal smooth muscle systematically deviated from a hyperbola. Such deviation occurred at values of force (P) approaching maximum isometric force (Po) for curves elicited by quick release at 2 and 10 s in the course of isometric contractions. Shortening velocities under a given afterload were overestimated at the high-force end (P > 75% Po) by Hill's equation; this implied that a relationship more complex than a simple hyperbola was involved at high loads. We next focused on finding an equation to also fit those directly measured data points that did not conform to a hyperbola. Our rationale in developing the equation was that a plot of the linearized transform of Hill's equation should yield a straight line over the entire range of loads at which velocities were measured. The plot demonstrated that, in the low-load high-velocity portion of the curve, a peak value was reached at 70–80% Po, which decreased as load increased in the high-load low-velocity portion.(ABSTRACT TRUNCATED AT 250 WORDS)

Shortening deactivation: quantifying a critical component of cyclical muscle contraction

2021 ◽  
Author(s):  
Amy K. Loya ◽  
Sarah K. Van Houten ◽  
Bernadette M. Glasheen ◽  
Douglas M. Swank
Keyword(s):  
Power Output ◽  
Muscle Activation ◽  
Muscle Relaxation ◽  
Length Change ◽  
Isometric Tension ◽  
Energetic Cost ◽  
Muscle Shortening ◽  
Shortening Deactivation ◽  
Muscle Types ◽  
Flight Muscles

A muscle undergoing cyclical contractions requires fast and efficient muscle activation and relaxation to generate high power with relatively low energetic cost. To enhance activation and increase force levels during shortening, some muscle types have evolved stretch activation (SA), a delayed increased in force following rapid muscle lengthening. SA's complementary phenomenon is shortening deactivation (SD), a delayed decrease in force following muscle shortening. SD increases muscle relaxation, which decreases resistance to subsequent muscle lengthening. While it might be just as important to cyclical power output, SD has received less investigation than SA. To enable mechanistic investigations into SD and quantitatively compare it to SA, we developed a protocol to elicit SA and SD from Drosophila and Lethocerus indirect flight muscles (IFM) and Drosophila jump muscle. When normalized to isometric tension, Drosophila IFM exhibited a 118% SD tension decrease, Lethocerus IFM dropped by 97%, and Drosophila jump muscle decreased by 37%. The same order was found for normalized SA tension: Drosophila IFM increased by 233%, Lethocerus IFM by 76%, and Drosophila jump muscle by only 11%. SD occurred slightly earlier than SA, relative to the respective length change, for both IFMs; but SD was exceedingly earlier than SA for jump muscle. Our results suggest SA and SD evolved to enable highly efficient IFM cyclical power generation and may be caused by the same mechanism. However, jump muscle SA and SD mechanisms are likely different, and may have evolved for a role other than to increase the power output of cyclical contractions.

Force-velocity and force-power properties of single muscle fibers from elite master runners and sedentary men

1996 ◽  
Vol 271 (2) ◽  
pp. C676-C683 ◽  
Author(s):  
J. J. Widrick ◽  
S. W. Trappe ◽  
D. L. Costill ◽  
R. H. Fitts
Keyword(s):  
Myosin Heavy Chain ◽  
Heavy Chain ◽  
Power Output ◽  
Peak Power ◽  
Isometric Force ◽  
Peak Force ◽  
Peak Power Output ◽  
Type I ◽  
Shortening Velocity ◽  
Force Velocity

Gastrocnemius muscle fiber bundles were obtained by needle biopsy from five middle-aged sedentary men (SED group) and six age-matched endurance-trained master runners (RUN group). A single chemically permeabilized fiber segment was mounted between a force transducer and a position motor, subjected to a series of isotonic contractions at maximal Ca2+ activation (15 degrees C), and subsequently run on a 5% polyacrylamide gel to determine myosin heavy chain composition. The Hill equation was fit to the data obtained for each individual fiber (r2 > or = 0.98). For the SED group, fiber force-velocity parameters varied (P < 0.05) with fiber myosin heavy chain expression as follows: peak force, no differences: peak tension (force/fiber cross-sectional area), type IIx > type IIa > type I; maximal shortening velocity (Vmax, defined as y-intercept of force-velocity relationship), type IIx = type IIa > type I; a/Pzero (where a is a constant with dimensions of force and Pzero is peak isometric force), type IIx > type IIa > type I. Consequently, type IIx fibers produced twice as much peak power as type IIa fibers, whereas type IIa fibers produced about five times more peak power than type I fibers. RUN type I and IIa fibers were smaller in diameter and produced less peak force than SED type I and IIa fibers. The absolute peak power output of RUN type I and IIa fibers was 13 and 27% less, respectively, than peak power of similarly typed SED fibers. However, type I and IIa Vmax and a/Pzero were not different between the SED and RUN groups, and RUN type I and IIa power deficits disappeared after power was normalized for differences in fiber diameter. Thus the reduced absolute peak power output of the type I and IIa fibers from the master runners was a result of the smaller diameter of these fibers and a corresponding reduction in their peak isometric force production. This impairment in absolute peak power production at the single fiber level may be in part responsible for the reduced in vivo power output previously observed for endurance-trained athletes.

THE EFFECT OF LEG PREFERENCE ON MECHANICAL EFFICIENCY DURING SINGLE-LEG EXTENSION EXERCISE

2021 ◽  
Author(s):  
Massimo Venturelli ◽  
Cantor Tarperi ◽  
Chiara Milanese ◽  
Luca Festa ◽  
Luana Toniolo ◽  
...  
Keyword(s):  
Muscle Activation ◽  
Near Infrared ◽  
Isometric Force ◽  
Fiber Type ◽  
Vastus Lateralis ◽  
Critical Role ◽  
Inverse Correlation ◽  
Mechanical Efficiency ◽  
Peak Power Output ◽  
Leg Extension

To investigate how leg preference affects net efficiency (ηnet), we examined central and peripheral hemodynamics, muscle fiber type, activation and force of preferred (PL) and non-preferred (NPL) leg. Our hypothesis was that PL greater efficiency could be explained by adaptations and interactions between central, peripheral factors and force. Fifteen young participants performed single-leg extension exercise at absolute (35W) and relative (50%peak power-output (Wpeak)) workloads with PL and NPL. Oxygen uptake, photoplethysmography, Doppler ultrasound, near-infrared-spectroscopy deoxy-hemoglobin [HHb], integrated electromyography (iEMG), maximal isometric force (MVC), rate of force development (RFD50-100) and muscle biopsies of both vastus lateralis, were studied to assess central and peripheral determinants of ηnet. During exercise executed at 35W, ηnet was 17.5±5.1% and 11.9±2.1% (p<0.01) in NP and NPL respectively, while during exercise at the 50% of Wpeak, was in PL = 18.1±5.1% and in NPL = 12.5±1.9 (p<0.01). The only parameter correlated with ηnet was iEMG which showed an inverse correlation for absolute (r=-0.83 and -0.69 for PL and NPL) and relative workloads (r=-0.92 and -0.79 for PL and NPL). MVC and RFD50-100 were higher in PL than in NPL but not correlated to ηnet. This study identified a critical role of leg preference in the efficiency during single-leg extension exercise. The whole spectrum of the central and peripheral, circulatory and muscular determinants of ηnet did not explain the difference between PL and NPL efficiency. Therefore, the lower muscle activation exhibited by the PL is likely the primary determinant of this physiological phenomenon.

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