scholarly journals Thermal dependence of contractile properties of skeletal muscle from the lizard Sceloporus occidentalis with comments on methods for fitting and comparing force-velocity curves

1986 ◽  
Vol 126 (1) ◽  
pp. 63-77 ◽  
Author(s):  
R. L. Marsh ◽  
A. F. Bennett
Keyword(s):  
Isometric Force ◽  
Muscle Length ◽  
Maximum Velocity ◽  
Contractile Properties ◽  
Linear Component ◽  
Thermal Dependence ◽  
Sceloporus Occidentalis ◽  
Twitch Force ◽  
Velocity Relationship ◽  
Force Velocity

The isometric and isotonic contractile properties of fast-twitch glycolytic fibres of the iliofibularis muscle (FG-IF) in the lizard Sceloporus occidentalis were measured in vitro at 5 degrees C intervals form 10 to 40 degrees C. The mean isometric parameters at 35 degrees C, the preferred body temperature of this species, were as follows: maximum isometric force (Po), 187 +/− 8 (S.E.M.) kNm-2; ratio of twitch force to tetanic force (PTW/Po), 0.46 +/− 0.02; time to peak twitch tension (tPTW), 7.0 +/− 0.3 ms; and time from peak twitch force to 50% relaxation (t50%), 8.2 +/− 0.3 ms. From 20 to 35 degrees C Po was almost constant (within 8% of the value at 35 degrees C). At 10 and 15 degrees C C. Po dropped to approximately 80% of the value at 35 degrees C. Po was very unstable at 40 degrees C. PTW/Po was almost constant at all temperatures. The time-related isometric parameters were positively modified by temperature at all temperatures measured (Q10 greater than 1.9). The force-velocity curves of the FG-IF deviated from the simple hyperbolic relation of A. V. Hill's characteristic equation. We present two alternative equations for fitting these data. These equations resulted in residual sums of squares from nonlinear least-squares analysis that were at least seven-fold lower than those from Hill's equation. The equation that best describes our data is a hyperbola modified by the addition of a linear component: V = B(1 - P/Po)/(A + P/Po) + C(1 - P/Po). To describe the curvature of this or any other force-velocity relationship, we propose the power ratio, Wmax/VmaxPo (where Wmax is the maximum power calculated from the force-velocity relationship and Vmax is the predicted maximum velocity of shortening at zero force). Vmax of the FG-IF was 21.9LoS-1 at 35 degrees C (where Lo is muscle length). This parameter was directly related to temperature between 10 and 35 degrees C with Q10 greater than 1.8. The shape of the force-velocity curve is not influenced by temperature (Wmax/VmaxPo = 0.11).

Myosin phosphorylation augments force-displacement and force-velocity relationships of mouse fast muscle

1995 ◽  
Vol 269 (3) ◽  
pp. C713-C724 ◽  
Author(s):  
R. W. Grange ◽  
C. R. Cory ◽  
R. Vandenboom ◽  
M. E. Houston
Keyword(s):  
Conditioning Stimulus ◽  
Muscle Length ◽  
Maximum Velocity ◽  
Twitch Force ◽  
Relative Load ◽  
Force Velocity ◽  
Active Peak ◽  
Isometric Twitch ◽  
Force Displacement

Two studies were conducted to examine the effect of myosin regulatory light chain (R-LC) phosphorylation on the rate and extent of shortening in submaximally activated mouse extensor digitorum longus muscles in vitro at 25 degrees C. For each study, R-LC phosphate content was increased fivefold by application of a 5-Hz, 20-s conditioning stimulus (CS) to 0.65-0.68 mol phosphate/mol R-LC; this level was sustained between 10 and 40 s after the CS. Maximum isometric twitch force and the maximum rate of force development (+dF/dtmax) were potentiated in the range 13-17% and 9-17% (P < 0.05), respectively, after the CS. In study 1, the maximal rate and extent of shortening were significantly enhanced by 10 and 21% (P < 0.001), respectively, when measured using a twitch zero-load clamp technique. In study 2, the force-velocity and force-displacement relationships were both augmented when determined with the twitch afterload technique. Displacement was enhanced between 20 and 82% for loads that ranged from 3 to 75% of active peak twitch force, whereas velocity was increased 6-8% over the same range (P < 0.05), including the predicted maximum velocity (Vmax; 5.08 vs. 4.69 muscle length/s). In both studies the increase in velocity likely represents a shift along the force-velocity relationship toward true Vmax that reflects a decrease in relative load due to force potentiation. Furthermore, with the decrease in relative load, displacement at a given load was also increased. Potentiated displacement and extent of R-LC phosphorylation also decreased in parallel when studied for 5 min after the CS. The increase in muscle shortening is a novel finding and suggests a function for R-LC phosphorylation with respect to movement because both peak work and power were also enhanced by up to 22%. These effects are consistent with an R-LC phosphorylation-induced increase in fapp, the apparent rate constant that describes the cross-bridge transition from the non-force-generating to the force-generating state.

Relative shortening velocity in locomotor muscles: turkey ankle extensors operate at low V/Vmax

2008 ◽  
Vol 294 (1) ◽  
pp. R200-R210 ◽  
Author(s):  
Annette M. Gabaldón ◽  
Frank E. Nelson ◽  
Thomas J. Roberts
Keyword(s):  
Isometric Force ◽  
Muscle Length ◽  
Shortening Velocity ◽  
Velocity Relationship ◽  
Locomotor Muscles ◽  
Force Velocity ◽  
Wild Turkeys ◽  
Strain Gauge Measurements ◽  
All Speeds ◽  
Level Running

The force-velocity properties of skeletal muscle have an important influence on locomotor performance. All skeletal muscles produce less force the faster they shorten and typically develop maximal power at velocities of ∼30% of maximum shortening velocity (Vmax). We used direct measurements of muscle mechanical function in two ankle extensor muscles of wild turkeys to test the hypothesis that during level running muscles operate at velocities that favor force rather than power. Sonomicrometer measurements of muscle length, tendon strain-gauge measurements of muscle force, and bipolar electromyographs were taken as animals ran over a range of speeds and inclines. These measurements were integrated with previously measured values of muscle Vmax for these muscles to calculate relative shortening velocity (V/Vmax). At all speeds for level running the V/Vmax values of the lateral gastrocnemius and the peroneus longus were low (<0.05), corresponding to the region of the force-velocity relationship where the muscles were capable of producing 90% of peak isometric force but only 35% of peak isotonic power. V/Vmax increased in response to the demand for mechanical power with increases in running incline and decreased to negative values to absorb energy during downhill running. Measurements of integrated electromyograph activity indicated that the volume of muscle required to produce a given force increased from level to uphill running. This observation is consistent with the idea that V/Vmax is an important determinant of locomotor cost because it affects the volume of muscle that must be recruited to support body weight.

Contractile properties of the striated adductor muscle in the bay scallop Argopecten irradians at several temperatures

1993 ◽  
Vol 176 (1) ◽  
pp. 175-193 ◽  
Author(s):  
J. M. Olson ◽  
R. L. Marsh
Keyword(s):  
Adductor Muscle ◽  
Contractile Properties ◽  
Temperature Sensitive ◽  
Maximal Velocity ◽  
Argopecten Irradians ◽  
Passive Force ◽  
Twitch Force ◽  
Peak Tension ◽  
Bay Scallop ◽  
Force Velocity

The isometric and isotonic contractile properties of the cross-striated adductor muscle of the bay scallop (Argopecten irradians) were measured in vitro at 10, 15 and 20 degrees C. The length at which twitch force was maximal as a function of the closed length in situ (L0/Lcl) averaged 1.38 +/− 0.01 (mean +/− S.E.M.) at 10 degrees C. This length is very close to the typical length at maximum gape during natural swimming at this temperature. Passive force was very low over the range of lengths measured here; at L0, passive force averaged approximately 0.08 N cm-2, or only 0.5% of the corresponding peak twitch force. The mean peak isometric twitch force (Ptw,max) at 10 degrees C was 21.43 +/− 0.68 N cm-2 (S.E.M.), and the ratio of peak twitch force to tetanic force (Ptw,max/P0) averaged 0.89 +/− 0.01. Temperature did not affect either twitch force (Ptw), once fatigue was taken into account, or Ptw,max/P0. In contrast, the time-related properties of twitch contractions (latent period, tL; time to peak tension, tPtw; and time from peak tension to half-relaxation, t50%R) were positively modified by temperature at all temperatures measured (Q10 &gt; 1.8). All three properties were more temperature-sensitive over the range 10–15 degrees C than over the range 15–20 degrees C. The force-velocity relationships of the striated adductor muscle were fitted to the hyperbolic-linear (HYP-LIN) equation. The force-velocity curves of the striated adductor muscle of the scallop were strongly influenced by temperature. Maximal velocity at zero force (Vmax), and therefore maximal power output, increased significantly with temperature. The Q10 over the temperature range 10–15 degrees C (1.42) was significantly lower than that over the range 15–20 degrees C (2.41). The shape of the force-velocity relationship, assessed through comparisons of the power ratio (Wmax/VmaxP0), was not influenced by temperature.

Isotonic relaxation in cardiac muscle

1975 ◽  
Vol 229 (3) ◽  
pp. 646-651 ◽  
Author(s):  
JE Strobeck ◽  
AS Bahler ◽  
EH Sonnenblick
Keyword(s):  
Cardiac Muscle ◽  
Isometric Force ◽  
Muscle Length ◽  
Constant Load ◽  
Papillary Muscles ◽  
Initial Length ◽  
Total Load ◽  
Relaxation Velocity ◽  
Force Velocity ◽  
Maximum Isometric Force

The force-velocity-length determinants of isotonic relaxation were studied in 12 cat papillary muscles. Isotonic relaxation velocity (VL) was found to be a function of total load (preload + afterload), with peak VL increasing to a maximum at loads approximately .3 to .4 Po(L') (Po(L') defined as maximum isometric force developed during a twitch at the experimental length) and falling with increasing loads. Initial muscle length (ML) had no effect on the peak VL with constant load. Increasing the initial length at which isotonic relaxation occurred (LL) decreased peak VL but did not alter the unique length-velocity trajectory at constant load. This unique length-velocity trajectory occurred, despite a wide variation in time during the contraction when peak VL was measured. Increasing Ca++ from 2.5 to 7.5 mM increased peak VL (1.73 +/- .16 to 2.32 +/- .20 ML/s) and shifted the entire length-velocity trajectory toward higher velocities of lengthening. The addition of 10 mM caffeine increased peak VL also (1.67 +/- .18 to 2.54 +/- .20 ML/s) and had a similar effect on the length-velocity trajectory during lengthening as Ca++. Both increased Ca++ and caffeine (10 mM) augmented the maximum VL measured on addition of load.

Peak power output is maintained in rabbit psoas and rat soleus single muscle fibers when CTP replaces ATP

1998 ◽  
Vol 85 (1) ◽  
pp. 76-83 ◽  
Author(s):  
Philip A. Wahr ◽  
Joseph M. Metzger
Keyword(s):  
Muscle Contraction ◽  
Peak Power ◽  
Muscle Length ◽  
Peak Power Output ◽  
Fiber Types ◽  
Rabbit Psoas ◽  
Cross Bridge ◽  
Chemomechanical Coupling ◽  
Velocity Relationship ◽  
Force Velocity

The chemomechanical coupling mechanism in striated muscle contraction was examined by changing the nucleotide substrate from ATP to CTP. Maximum shortening velocity [extrapolation to zero force from force-velocity relation ( V max) and slope of slack test plots ( V 0)], maximum isometric force (Po), power, and the curvature of the force-velocity curve [ a/Po(dimensionless parameter inversely related to the curvature)] were determined during maximum Ca2+-activated isotonic contractions of fibers from fast rabbit psoas and slow rat soleus muscles by using 0.2 mM MgATP, 4 mM MgATP, 4 mM MgCTP, or 10 mM MgCTP as the nucleotide substrate. In addition to a decrease in the maximum Ca2+-activated force in both fiber types, a change from 4 mM ATP to 10 mM CTP resulted in a decrease in V max in psoas fibers from 3.26 to 1.87 muscle length/s. In soleus fibers, V max was reduced from 1.94 to 0.90 muscle length/s by this change in nucleotide. Surprisingly, peak power was unaffected in either fiber type by the change in nucleotide as the result of a three- to fourfold decrease in the curvature of the force-velocity relationship. The results are interpreted in terms of the Huxley model of muscle contraction as an increase in f 1and g 1 coupled to a decrease in g 2(where f 1 is the rate of cross-bridge attachment and g 1 and g 2 are rates of detachment) when CTP replaces ATP. This adequately accounts for the observed changes in Po, a/Po, and V max. However, the two-state Huxley model does not explicitly reveal the cross-bridge transitions that determine curvature of the force-velocity relationship. We hypothesize that a nucleotide-sensitive transition among strong-binding cross-bridge states following Pi release, but before the release of the nucleotide diphosphate, underlies the alterations in a/Poreported here.

Force–Velocity Relationship of Upper Body Muscles: Traditional Versus Ballistic Bench Press

2016 ◽  
Vol 32 (2) ◽  
pp. 178-185 ◽  
Author(s):  
Amador García-Ramos ◽  
Slobodan Jaric ◽  
Paulino Padial ◽  
Belén Feriche
Keyword(s):  
Bench Press ◽  
Maximum Velocity ◽  
Maximum Force ◽  
Upper Body ◽  
Strongly Correlated ◽  
Mean Values ◽  
Repetition Maximum ◽  
Velocity Relationship ◽  
Force Velocity ◽  
Relationship Of

This study aimed to (1) evaluate the linearity of the force–velocity relationship, as well as the reliability of maximum force (F0), maximum velocity (V0), slope (a), and maximum power (P0); (2) compare these parameters between the traditional and ballistic bench press (BP); and (3) determine the correlation of F0 with the directly measured BP 1-repetition maximum (1RM). Thirty-two men randomly performed 2 sessions of traditional BP and 2 sessions of ballistic BP during 2 consecutive weeks. Both the maximum and mean values of force and velocity were recorded when loaded by 20–70% of 1RM. All force–velocity relationships were strongly linear (r > .99). While F0 and P0 were highly reliable (ICC: 0.91–0.96, CV: 3.8–5.1%), lower reliability was observed for V0 and a (ICC: 0.49–0.81, CV: 6.6–11.8%). Trivial differences between exercises were found for F0 (ES: < 0.2), however the a was higher for the traditional BP (ES: 0.68–0.94), and V0 (ES: 1.04–1.48) and P0 (ES: 0.65–0.72) for the ballistic BP. The F0 strongly correlated with BP 1RM (r: 0.915–0.938). The force–velocity relationship is useful to assess the upper body maximal capabilities to generate force, velocity, and power.

scholarly journals Force-Velocity Relationship in the Countermovement Jump Exercise Assessed by Different Measurement Methods

2019 ◽  
Vol 67 (1) ◽  
pp. 37-47 ◽  
Author(s):  
Amador García-Ramos ◽  
Alejandro Pérez-Castilla ◽  
Antonio J. Morales-Artacho ◽  
Filipa Almeida ◽  
Paulino Padial ◽  
...  
Keyword(s):  
Maximum Velocity ◽  
Measurement Methods ◽  
Loading Conditions ◽  
Countermovement Jump ◽  
Mean Values ◽  
Velocity Transducer ◽  
Jump Exercise ◽  
Velocity Relationship ◽  
Force Velocity ◽  
The Mean

AbstractThis study aimed to compare force, velocity, and power output collected under different loads, as well as the force-velocity (F-V) relationship between three measurement methods. Thirteen male judokas were tested under four loading conditions (20, 40, 60, and 80 kg) in the countermovement jump (CMJ) exercise, while mechanical output data were collected by three measurement methods: the Samozino's method (SAM), a force platform (FP), and a linear velocity transducer (LVT). The variables of the linear F-V relationship (maximum force [F0], maximum velocity [V0], F-V slope, and maximum power [P0]) were determined. The results revealed that (1) the LVT overestimated the mechanical output as compared to the SAM and FP methods, especially under light loading conditions, (2) the SAM provided the lowest magnitude for all mechanical output, (3) the F-V relationships were highly linear either for the SAM (r = 0.99), FP (r = 0.97), and LVT (r = 0.96) methods, (4) the F-V slope obtained by the LVT differed with respect to the other methods due to a larger V0 (5.28 ± 1.48 m·s-1) compared to the SAM (2.98 ± 0.64 m·s-1) and FP (3.06 ± 0.42 m·s-1), and (5) the methods were significantly correlated for F0 and P0, but not for V0 or F-V slope. These results only support the accuracy of the SAM and FP to determine the F-V relationship during the CMJ exercise. The very large correlations of the SAM and LVT methods with respect to the FP (presumed gold-standard) for the mean values of force, velocity and power support their concurrent validity for the assessment of mechanical output under individual loads.

scholarly journals Power Output and Force-Velocity Relationship of Live Fibres from White Myotomal Muscle of the Dogfish, Scyliorhinus Canicula

1988 ◽  
Vol 140 (1) ◽  
pp. 187-197 ◽  
Author(s):  
N. A. CURTIN ◽  
R. C. WOLEDGE
Keyword(s):  
Power Output ◽  
Maximum Velocity ◽  
Muscle Fibres ◽  
Fish Length ◽  
Skinned Fibres ◽  
Step Method ◽  
Velocity Relationship ◽  
Velocity Of Shortening ◽  
Force Velocity ◽  
Myotomal Muscle

The relationship between force and velocity of shortening and between power and velocity were examined for myotomal muscle fibre bundles from the dogfish. The maximum velocity of shortening, mean value 4.8 ± 0.2 μms−1 half sarcomere−1 (±S.E.M., N = 13), was determined by the ‘slack step’ method (Edman, 1979) and was found to be independent of fish length. The force-velocity relationship was hyperbolic, except at the high-force end where the observations were below the hyperbola fitted to the rest of the data. The maximum power output was 91 ± 14 W kg−1 wet mass (±S.E.M., N = 7) at a velocity of shortening of 1.3 ± 0.13μms−1 halfsarcomere−1 (±S.E.M., N = 7). This power output is considerably higher than that previously reported for skinned fibres (Bone et al. 1986). Correspondingly the force-velocity relationship is less curved for intact fibres than for skinned fibres. The maximum swimming speed (normalized for fish length) predicted from the observed power output of the muscle fibres decreased with increasing fish size; it ranged from 12.9 to 7.8 fish lengths s−1 for fish 0155–0.645m in length.

scholarly journals The effects of inorganic phosphate on muscle force development and energetics: challenges in modelling related to experimental uncertainties

2019 ◽  
Author(s):  
Alf Månsson
Keyword(s):  
Inorganic Phosphate ◽  
Muscle Force ◽  
Isometric Force ◽  
Shortening Velocity ◽  
Apparent Contradiction ◽  
Sequence Of Events ◽  
Velocity Relationship ◽  
Force Velocity ◽  
Cross Bridges ◽  
Experimental Findings

Abstract Muscle force and power are developed by myosin cross-bridges, which cyclically attach to actin, undergo a force-generating transition and detach under turnover of ATP. The force-generating transition is intimately associated with release of inorganic phosphate (Pi) but the exact sequence of events in relation to the actual Pi release step is controversial. Details of this process are reflected in the relationships between [Pi] and the developed force and shortening velocity. In order to account for these relationships, models have proposed branched kinetic pathways or loose coupling between biochemical and force-generating transitions. A key hypothesis underlying the present study is that such complexities are not required to explain changes in the force–velocity relationship and ATP turnover rate with altered [Pi]. We therefore set out to test if models without branched kinetic paths and Pi-release occurring before the main force-generating transition can account for effects of varied [Pi] (0.1–25 mM). The models tested, one assuming either linear or non-linear cross-bridge elasticity, account well for critical aspects of muscle contraction at 0.5 mM Pi but their capacity to account for the maximum power output vary. We find that the models, within experimental uncertainties, account for the relationship between [Pi] and isometric force as well as between [Pi] and the velocity of shortening at low loads. However, in apparent contradiction with available experimental findings, the tested models produce an anomalous force–velocity relationship at elevated [Pi] and high loads with more than one possible velocity for a given load. Nevertheless, considering experimental uncertainties and effects of sarcomere non-uniformities, these discrepancies are insufficient to refute the tested models in favour of more complex alternatives.

scholarly journals Effect of Muscle Length on the Force-Velocity Relationship of Tetanized Cardiac Muscle

1972 ◽  
Vol 31 (2) ◽  
pp. 195-206 ◽  
Author(s):  
Robert Formon ◽  
Lincoln E. Ford ◽  
Edmund H. Sonnenblick
Keyword(s):  
Cardiac Muscle ◽  
Muscle Length ◽  
Velocity Relationship ◽  
Force Velocity ◽  
Relationship Of
Sign in / Sign up

Export Citation Format

Share Document