Force-velocity shifts with repetitive isometric and isotonic contractions of canine gastrocnemius in situ

Ameredes, Bill T.; Brechue, William F.; Andrew, G. M.; Stainsby, W. N.

doi:10.1152/jappl.1992.73.5.2105

Cited by 26 publications

(25 citation statements)

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“…However, in some cases, there is a clear indication of the break (2,21,28). A departure from the hyperbolic relationship has also been reported for isolated myosin (25) as well as for cardiac trabeculae (10).…”

Section: Discussionmentioning

confidence: 71%

The biphasic force-velocity relationship in whole rat skeletal muscle in situ

Devrome¹,

MacIntosh²

2007

Journal of Applied Physiology

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Devrome AN, MacIntosh BR. The biphasic force-velocity relationship in whole rat skeletal muscle in situ. J Appl Physiol 102: [2294][2295][2296][2297][2298][2299][2300] 2007. First published April 5, 2007; doi:10.1152/japplphysiol.00276.2006.-Edman has reported that the force-velocity relationship (FVR) departs from Hill's classic hyperbola near 0.80 of measured isometric force (J Physiol 404: 301-321, 1988). The purpose of this study was to investigate the biphasic nature of the FVR in the rested state and after some recovery from fatigue in the rat medial gastrocnemius muscle in situ. Force-velocity characteristics were determined before and during recovery from fatigue induced by intermittent stimulation at 170 Hz for 100 ms each second for 6 min. Force-velocity data were obtained for isotonic contractions with 100 ms of 200-Hz stimulation, including several measurements with loads above 0.80 of measured isometric force. The force-velocity data obtained in this study were fit well by a double-hyperbolic equation. A departure from Hill's classic hyperbola was found at 0.88 Ϯ 0.01 of measured isometric force, which is higher than the ϳ0.80 reported by Edman et al. for isolated frog fibers. After 45 min of recovery, maximum shortening velocity was 86 Ϯ 2% of prefatigue, but neither curvature nor predicted isometric force was significantly different from prefatigue. The location of the departure from Hill's classic hyperbola was not different after this recovery from the fatiguing contractions. Including an isometric point in the data set will not yield the same values for maximal velocity and the degree of curvature as would be obtained using the double hyperbola approach. Data up to 0.88 of measured isometric force can be used to fit data to the Hill equation.fatigue; contractile properties; double hyperbola; maximal velocity THE RELATIONSHIP BETWEEN MUSCLE shortening velocity and the load that is imposed on muscle is known as the force-velocity relationship (FVR), where velocity of shortening decreases for progressively higher loads. In 1938, A. V. Hill reported the classic equation that is most often used by researchers to characterize the FVR in skeletal muscle (17)where P is force at any velocity of shortening, V; P o * is predicted isometric force, and a and b are constants. The maximal velocity of shortening (V max ) can be estimated by solving the equation for P ϭ 0, once the constants are known. The ratio a/P o *, describes the magnitude of curvature of the relationship, with a higher value indicating a lesser curvature.Although Hill's equation is used most frequently when force-velocity data are fit to an equation, several studies have shown that the force-velocity properties of muscle do not fit the simple rectangular hyperbola over the full range of values for force and velocity (1,(12)(13)(14)(15). Rather, there is a departure of measured values from the predicted hyperbola at high forces where velocity of shortening is low. According to Edman et al. (14), this departure from the traditional rectang...

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Section: Discussionmentioning

confidence: 71%

The biphasic force-velocity relationship in whole rat skeletal muscle in situ

Devrome¹,

MacIntosh²

2007

Journal of Applied Physiology

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“…This is illustrated in Fig. 4 Stainsby (1992). In the first four stuidies the maximum (unloaded) shortening selocity (VQ) Uvas measured; in the others, data points refer to malximtlnm shortening selocity (Wmax) extrapolated from force velocity (P-V) salues.…”

Section: Reduction Of Maximum Isometric Forcementioning

confidence: 95%

Muscle cell function during prolonged activity: cellular mechanisms of fatigue

Dg¹,

Lännergren²,

Westerblad³

1995

Experimental Physiology

292

283

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Muscle performance declines during prolonged and intense activity; important components are a reduction in force production and shortening velocity and a prolongation of relaxation. In this review we consider how the changes in metabolites (particularly H+, inorganic phosphate (Pi), ATP and ADP) and changes in sarcoplasmic reticulum Ca2+ release lead to the observed changes in force, shortening velocity and relaxation. The reduced force is caused by a combination of reduced maximum force‐generating capacity, reduced myofibrillar Ca2+ sensitivity and reduced Ca2+ release. The reduced maximum force and Ca2+ sensitivity are largely explained by the effects of H+ and Pi that have been observed in skinned fibres. At least three different forms of reduced Ca2+ release can be recognized but the mechanisms involved are incompletely understood. The reduced shortening velocity can be partly explained by the effects of H+ that have been observed in skinned fibres. In addition it is proposed that ADP, which depresses shortening velocity, increases during contractions to a level that is considerably higher than existing measurements suggest. Changes in Ca2+ release are probably unimportant for the reduced shortening velocity. The prolongation of relaxation can arise both from slowing of the rate of decline of myoplasmic calcium concentration and from slowing of cross‐bridge detachment rates. A method of analysis which separates these components is described. The increase in H+ and the other metabolite changes during fatigue can independently affect both components. Finally we show that reduced force, shortening velocity and slowed relaxation all contribute to the decline in muscle performance during a working cycle in which the muscle first shortens actively and then is stretched passively by an antagonist muscle.

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“…In general, mammalian muscle demonstrates very little curvature (a high a/Po ratio [2,9]). Ameredes et al [3] reported a/Po ratios of 1.0 to 1.6 for dog gastrocnemius-plantaris muscle in situ. Maximal velocity under the conditions of these experiments was similar to values previously reported for the rat medial gastrocnemius muscle under similar circumstances.…”

Section: General Force-velocity Propertiesmentioning

confidence: 96%

Potentiation of shortening and velocity of shortening during repeated isotonic tetanic contractions in mammalian skeletal muscle

MacIntosh

Bryan

2002

Pflugers Arch - Eur J Physiol

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The purpose of this study was to investigate the enhancement of shortening and of the velocity of shortening during repeated incompletely fused isotonic tetanic contractions. The medial gastrocnemius muscle of anesthetized rats was isolated in situ and the motor nerve stimulated with supramaximal pulses, 50 micros duration, at optimal length. Estimated maximal velocity of shortening (V(max)) was 210 +/- 6 mm x s(-1) (mean +/- SEM). Repeated incompletely fused tetanic contractions (three pulses at 80 Hz) resulted in initial shortening which was 1.5 +/- 0.1 mm, and this increased to 2.7 +/- 0.2 mm after 7 s of 4 s(-1) contractions. Peak velocity of shortening for intermittent 80 Hz stimulation increased from 60.5 +/- 4 mm x s(-1) to 91.8 +/- plus minus 6 mm x s(-1). The initial velocity of shortening for 80 Hz stimulation was substantially less than the velocity of shortening observed with 200 Hz stimulation, but increased to 72 +/- 3% of the load-specific value for 200 Hz stimulation. Myosin regulatory light chain phosphorylation increased from 11.1 +/- 1.5% at rest to 32.9 +/- 5.4% after 4 s of intermittent 80 Hz stimulation and 50.4 +/- 8.8% after 7 s ( P<0.01). The ascending limb of the length-force relationship was determined with tetanic contractions, 200 Hz for 100 ms. At the length corresponding to peak shortening after 7 s of repeated 80 Hz contractions, the maximal isometric force was five times greater than the isotonic load. The rate of phosphorylation was sustained from 4 to 7 s, but the rate of increase in shortening and velocity decreased. The slower rate of change in shortening and velocity may be due to approaching maximal velocity for this short duration of contraction, but is not due to slowing of the rate of phosphorylation of the myosin regulatory light chains.

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Force-velocity shifts with repetitive isometric and isotonic contractions of canine gastrocnemius in situ

Cited by 26 publications

References 0 publications

The biphasic force-velocity relationship in whole rat skeletal muscle in situ

The biphasic force-velocity relationship in whole rat skeletal muscle in situ

Muscle cell function during prolonged activity: cellular mechanisms of fatigue

Potentiation of shortening and velocity of shortening during repeated isotonic tetanic contractions in mammalian skeletal muscle

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