scholarly journals Effect of osmotic compression on the force-velocity properties of glycerinated rabbit skeletal muscle cells.

1991 ◽  
Vol 97 (1) ◽  
pp. 73-88 ◽  
Author(s):  
L E Ford ◽  
K Nakagawa ◽  
J Desper ◽  
C Y Seow
Keyword(s):  
Isometric Force ◽  
Maximum Velocity ◽  
Psoas Muscle ◽  
Maximum Power ◽  
Half Maximum ◽  
Control Value ◽  
Relative Maximum ◽  
Maximum Activation ◽  
Force Velocity ◽  
Full Activation

The force-velocity relations of single glycerinated rabbit psoas muscle fibers at 5 degrees C were studied at maximum and half-maximum activation in the presence of 0 (control) and 39-145 g/liter dextran T-70. Resting fiber diameter decreased progressively to approximately 70% of the nondextran control as the dextran concentration was increased. Isometric force at full activation increased to a maximum of 136% of control at 111 g/liter dextran and then fell to 80% of control in 145 g/liter dextran. Maximum velocity, which fell to 49% of the control value in the highest concentration of dextran, was nearly constant at approximately 65% control over the range of 58-111 g/liter dextran. Relative maximum power, which gives an estimate of changes in intermediate velocity, was not significantly reduced by dextran concentrations up to 76 g/liter, but then fell progressively to 62% of control in the highest concentration of dextran. At half-maximum activation, maximum velocity and relative maximum power were not significantly different from the values at full activation. The results obtained at partial activation indicate that the decline of velocity seen in the presence of dextran is not due to a passive internal load and that the dextran does not cause a viscous resistance to shortening. The increased velocity in the absence of dextran can be explained by the reduced ability of cross-bridges to resist shortening, as proposed by Goldman (1987. Biophys. J. 51:57).

scholarly journals The maximum shortening velocity of muscle should be scaled with activation

1999 ◽  
Vol 86 (3) ◽  
pp. 1025-1031 ◽  
Author(s):  
John W. Chow ◽  
Warren G. Darling
Keyword(s):  
Isometric Force ◽  
Musculoskeletal Modeling ◽  
Type Model ◽  
Shortening Velocity ◽  
Activation Level ◽  
Maximum Activation ◽  
Force Velocity ◽  
Maximum Isometric Force ◽  
Release Method ◽  
Wrist Flexors

The purpose of this study was to determine whether the maximum shortening velocity ( V max) in Hill’s mechanical model (A. V. Hill. Proc. R. Soc. London Ser. B. 126: 136–195, 1938) should be scaled with activation, measured as a fraction of the maximum isometric force (Fmax). By using the quick-release method, force-velocity (F-V) relationships of the wrist flexors were gathered at five different activation levels (20–100% of maximum at intervals of 20%) from four subjects. The F-V data at different activation levels can be fitted remarkably well with Hill’s characteristic equation. In general, the shortening velocity decreases with activation. With the assumption of nonlinear relationships between Hill constants and activation level, a scaled V max model was developed. When the F-V curves for submaximal activation were forced to converge at the V max obtained with maximum activation (constant V max model), there were drastic changes in the shape of the curves. The differences in V max values generated by the scaled and constant V max models were statistically significant. These results suggest that, when a Hill-type model is used in musculoskeletal modeling, the V max should be scaled with activation.

The Novel Single-Stroke Kayak Test: Can It Discriminate Between 200-m and Longer-Distance (500- and 1000-m) Specialists in Canoe Sprint?

2020 ◽  
pp. 1-8 ◽  
Author(s):  
Milos R. Petrovic ◽  
Amador García-Ramos ◽  
Danica N. Janicijevic ◽  
Alejandro Pérez-Castilla ◽  
Olivera M. Knezevic ◽  
...  
Keyword(s):  
Bench Press ◽  
Maximum Velocity ◽  
Maximum Power ◽  
Maximum Force ◽  
Upper Body ◽  
Traditional Resistance Training ◽  
Force Velocity ◽  
The Individual ◽  
Pull Tests ◽  
Training Exercises

Purpose: To test whether the force–velocity (F–V) relationship obtained during a specific single-stroke kayak test (SSKT) and during nonspecific traditional resistance-training exercises (bench press and prone bench pull) could discriminate between 200-m specialists and longer-distance (500- and 1000-m) specialists in canoe sprint. Methods: A total of 21 experienced male kayakers (seven 200-m specialists and 14 longer-distance specialists) participated in this study. After a familiarization session, kayakers came to the laboratory on 2 occasions separated by 48 to 96 hours. In a randomized order, kayakers performed the SSKT in one session and the bench press and bench pull tests in another session. Force and velocity outputs were recorded against 5 loads in each exercise to determine the F–V relationship and related parameters (maximum force, maximum velocity, F–V slope, and maximum power). Results: The individual F–V relationships were highly linear for the SSKT (r = .990 [.908, .998]), bench press (r = .993 [.974, .999]), and prone bench pull (r = .998 [.992, 1.000]). The F–V relationship parameters (maximum force, maximum velocity, and maximum power) were significantly higher for 200-m specialists compared with longer-distance specialists (all Ps ≤ .047) with large effect sizes (≥0.94) revealing important practical differences. However, no significant differences were observed between 200-m specialists and longer-distance specialists in the F–V slope (P ≥ .477). Conclusions: The F–V relationship assessed during both specific (SSKT) and nonspecific upper-body tasks (bench press and bench pull) may distinguish between kayakers specialized in different distances.

Effects of Combined Training Loads on Relations Among Force, Velocity, and Power Development

1997 ◽  
Vol 22 (4) ◽  
pp. 328-336 ◽  
Author(s):  
Hideki Toji ◽  
Kensaku Suei ◽  
Masahiro Kaneko
Keyword(s):  
Muscle Power ◽  
Maximum Velocity ◽  
Maximum Power ◽  
Maximum Strength ◽  
Combined Training ◽  
Effective Form ◽  
Significant Difference ◽  
Velocity Relation ◽  
Force Velocity ◽  
Key Words Muscle

The effects of different training programs on the force-velocity relation and the maximum power output from the elbow flexor muscles were examined in 12 male adults. The subjects were divided into two equal groups (G30 + 100 and G30 + 0), In the G30 + 100 group, training was performed with five, repetitions at 30% maximum strength (Fmax) and five isometric contractions (100% Fmax) and in the G30 + 0 group with five repetitions at 30% Fmax and five contractions with no load (0% Fmax). Training was performed 3 days a week for 11 weeks. Maximum power increased significantly in both groups after training. The power increase was significantly greater in the G30 + 100 group. Maximum strength was significantly higher only in the G30 + 100 group, while maximum velocity increased in both groups. No significant difference in strength or velocity gain was observed between the two groups. These results suggest that isometric training at maximum strength (100% Fmax) is a more effective form of supplementary training to increase power production than no load training at maximum velocity. Key words: muscle training, force-velocity relation, muscle power

Effects of microtubules and microfilaments on [Ca2+]i and contractility in a reconstituted fibroblast fiber

2000 ◽  
Vol 279 (3) ◽  
pp. C785-C796 ◽  
Author(s):  
Kazuo Obara ◽  
Koji Nobe ◽  
Hiromi Nobe ◽  
Michael S. Kolodney ◽  
Primal De Lanerolle ◽  
...  
Keyword(s):  
Isometric Force ◽  
Calf Serum ◽  
Maximum Velocity ◽  
Mechanical Resistance ◽  
Cross Sectional ◽  
3T3 Fibroblasts ◽  
Primary Determinant ◽  
Intracellular Ca ◽  
Force Velocity ◽  
Contraction And Relaxation

We used a reconstituted fiber formed when 3T3 fibroblasts are grown in collagen to characterize nonmuscle contractility and Ca2+ signaling. Calf serum (CS) and thrombin elicited reversible contractures repeatable for >8 h. CS elicited dose-dependent increases in isometric force; 30% produced the largest forces of 106 ± 12 μN ( n = 30), which is estimated to be 0.5 mN/mm2 cell cross-sectional area. Half times for contraction and relaxation were 4.7 ± 0.3 and 3.1 ± 0.3 min at 37°C. With imposition of constant shortening velocities, force declined with time, yielding time-dependent force-velocity relations. Forces at 5 s fit the hyperbolic Hill equation; maximum velocity ( V max) was 0.035 ± 0.002 Lo/s. Compliance averaged 0.0076 ± 0.0006 Lo/Fo. Disruption of microtubules with nocodazole in a CS-contracted fiber had no net effects on force, V max, or stiffness; force increased in 8, but decreased in 13, fibers. Nocodazole did not affect baseline intracellular Ca2+ concentration ([Ca2+]i) but reduced (∼30%) the [Ca2+]i response to CS. The force after nocodazole treatment was the primary determinant of stiffness and V max, suggesting that microtubules were not a major component of fiber internal mechanical resistance. Cytochalasin D had major inhibitory effects on all contractile parameters measured but little effect on [Ca2+]i.

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).

Isometric and isovelocity contractile performance of red musle fibres from the dogfishScyliorhinus canicula

2002 ◽  
Vol 205 (11) ◽  
pp. 1585-1595 ◽  
Author(s):  
F. Lou ◽  
N. A. Curtin ◽  
R. C. Woledge
Keyword(s):  
Isometric Force ◽  
Maximum Velocity ◽  
Test Method ◽  
Muscle Fibres ◽  
Shortening Velocity ◽  
Fibre Bundles ◽  
Series Elasticity ◽  
In Series ◽  
Force Velocity ◽  
Maximum Isometric Force

SUMMARYMaximum isometric tetanic force produced by bundles of red muscle fibres from dogfish, Scyliorhinus canicula (L.), was 142.4±10.3 kN m-2 (N=35 fibre bundles); this was significantly less than that produced by white fibres 289.2±8.4 kN m-2(N=25 fibre bundles) (means ± S.E.M.). Part, but not all, of the difference is due to mitochondrial content. The maximum unloaded shortening velocity, 1.693±0.108 L0 s-1(N=6 fibre bundles), was measured by the slack-test method. L0 is the length giving maximum isometric force. The force/velocity relationship was investigated using a step-and-ramp protocol in seven red fibre bundles. The following equation was fitted to the data:[(P/P0)+(a/P0)](V+b)=[(P0*/P0)+(a/P0)]b,where P is force during shortening at velocity V,P0 is the isometric force before shortening, and a, band P0* are fitted constants. The fitted values were P0*/P0=1.228±0.053, Vmax=1.814±0.071 L0s-1, a/P0=0.269±0.024 and b=0.404±0.041 L0 s-1(N=7 for all values). The maximum power was 0.107±0.005P0Vmax and was produced during shortening at 0.297±0.012Vmax. Compared with white fibres from dogfish, the red fibres have a lower P0 (49%) and Vmax (48%), but the shapes of the force/velocity curves are similar. Thus, the white and red fibres have equal capacities to produce power within the limits set by the isometric force and maximum velocity of shortening of each fibre type. A step shortening of 0.050±0.003L0 (N=7) reduced the maximum isometric force in the red fibres' series elasticity to zero. The series elasticity includes all elastic structures acting in series with the attached cross-bridges. Three red fibre bundles were stretched at a constant velocity, and force (measured when length reached L0) was 1.519±0.032P0. In the range of velocities used here, -0.28 to -0.63Vmax, force varied little with the velocity.

scholarly journals Force-Velocity Profile of Competitive Kayakers: Evaluation of a Novel Single Kayak Stroke Test

2021 ◽  
Vol 80 (1) ◽  
pp. 49-59
Author(s):  
Milos Petrovic ◽  
Amador Garcia-Ramos ◽  
Danica Janicijevic ◽  
Alejandro Perez-Castilla ◽  
Olivera M. Knezevic ◽  
...  
Keyword(s):  
Bench Press ◽  
Maximum Velocity ◽  
Maximum Power ◽  
Maximum Force ◽  
Upper Body ◽  
Maximal Velocity ◽  
Female Age ◽  
Fatigue Monitoring ◽  
Force Velocity ◽  
The Individual

Abstract The assessment of the force-velocity (F-V) profile in athletes may have important applications for training prescription, injury management, and fatigue monitoring. This study aimed to assess whether a novel single kayak stroke test (SKST) is able to provide the F-V relationship variables (maximum force, maximum velocity and maximum power) of competitive kayakers with acceptable reliability and external validity. Six female (age: 20.3 ± 3.7 years) and eight male (age: 20.8 ± 2.4 years) elite kayakers performed the SKST, bench press, bench pull, and short Wingate kayak test. The individual F-V relationships were highly linear [median r (range): left stroke = 0.986 (0.897 - 0.998); right stroke = 0.987 (0.971 - 0.999)]. The reliability of the F-V relationship parameters obtained during the SKST was high (within-session: CV ≤ 4.48% and ICC ≥ 0.93; between-session: CV ≤ 8.06% and ICC ≥ 0.65). The validity of the F-V relationship parameters obtained during the SKST was generally very high for maximum power (r range = 0.825 - 0.975), high for maximum force during both the bench press and the bench pull (r range = 0.751 - 0.831), and high or moderate for maximal velocity during the bench pull (r = 0.770 - 0.829) and the bench press (r = 0.355 - 0.471), respectively. The SKST can be considered a feasible procedure for testing the maximal upper-body muscle mechanical capacities of kayakers.

Injury to skeletal muscle fibers of mice following lengthening contractions

1985 ◽  
Vol 59 (1) ◽  
pp. 119-126 ◽  
Author(s):  
K. K. McCully ◽  
J. A. Faulkner
Keyword(s):  
Skeletal Muscle ◽  
Isometric Force ◽  
Muscle Fibers ◽  
Lengthening Contractions ◽  
Control Value ◽  
Skeletal Muscle Fibers ◽  
Maximum Isometric Force ◽  
Distal Tendon ◽  
Shortening Contractions

We tested the hypothesis that lengthening contractions result in greater injury to skeletal muscle fibers than isometric or shortening contractions. Mice were anesthetized with pentobarbital sodium and secured to a platform maintained at 37 degrees C. The distal tendon of the extensor digitorum longus muscle was attached to a servomotor. A protocol consisting of isometric, shortening, or lengthening contractions was performed. After the contraction protocol the distal tendon was reattached, incisions were closed, and the mice were allowed to recover. The muscles were removed after 1–30 days, and maximum isometric force (Po) was measured in vitro at 37 degrees C. Three days after isometric and shortening contractions and sham operations, histological appearance was not different from control and Po was 80% of the control value. Three days after lengthening contractions, histological sections showed that 37 +/- 4% of muscle fibers degenerated and Po was 22 +/- 3% of the control value. Muscle regeneration, first seen at 4 days, was nearly complete by 30 days, when Po was 84 +/- 3% of the control value. We conclude that, with the protocol used, lengthening, but not isometric or shortening contractions, caused significant injury to muscle fibers.

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.

Comparative force-velocity relation and analyses of myosin of dog atria and ventricles

1982 ◽  
Vol 243 (3) ◽  
pp. H391-H397 ◽  
Author(s):  
J. Wikman-Coffelt ◽  
H. Refsum ◽  
G. Hollosi ◽  
L. Rouleau ◽  
L. Chuck ◽  
...  
Keyword(s):  
Atpase Activity ◽  
Calcium Concentration ◽  
Maximum Velocity ◽  
Calcium Sensitivity ◽  
Myofibrillar Proteins ◽  
Maximal Velocity ◽  
Velocity Of Shortening ◽  
Force Velocity ◽  
Normal Calcium ◽  
Actin Concentration

The isolated muscle and purified myofibrillar proteins of canine atria and ventricles were compared relative to force-velocity relations and rate of adenosine 5'-triphosphatase (ATPase) activity as a function of calcium concentrations. The maximal stress development of isolated trabeculae of canine atria was similar to that of canine right ventricular papillary muscles when analyzed at saturating calcium concentrations (7.5 mM); however, stress was less in the atria when studied at normal calcium concentrations (2.5 mM). The maximal velocity of shortening of atrial trabeculae was about 2.3 times higher than that of ventricular muscle. Regulated actomyosin characterized from the myofibrillar proteins of the two tissues gave directionally similar calcium sensitivity. The maximum velocity of shortening for actin-activated atrial myosin of the dog was approximately 1.8 times higher when the latter was analyzed as a function of actin concentration. Both maximal tension of isolated muscle and regulated actomyosin ATPase activity were dependent on calcium concentration.

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