Mechanical transients initiated by ramp stretch and release to Po in frog muscle fibers

Cavagna, G; Mazzanti, Marinella; Heglund, Norman; Citterio, G.

doi:10.1152/ajpcell.1986.251.4.c571

Cited by 40 publications

(23 citation statements)

References 13 publications

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“…Figures 6 and 7 show that when the ramp stretch is large (greater than -2%), transient shortening against To attains about the same value independent of the velocity of lengthening. When the stretch is small and the velocity of lengthening is high, an oscillatory response of the sarcomere length changes may take place after release (Pringle, 1949;Armstrong, Huxley & Julian, 1966;Cavagna et al 1986). …”

Section: Resultsmentioning

confidence: 99%

Storage and release of mechanical energy by contracting frog muscle fibres.

Cavagna

Heglund

Harry

et al. 1994

The Journal of Physiology

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1. Stretching a contracting muscle leads to greater mechanical work being done during subsequent shortening by its contractile component; the mechanism of this enhancement is not known. 2. This mechanism has been investigated here by subjecting tetanized frog muscle fibres to ramp stretches followed by an isotonic release against a load equal to the maximum isometric tension, To. Shortening against To was taken as direct evidence of an absolute increase in the ability to do work as a consequence of the previous stretch. 3. Ramp stretches (0-5-8-6% sarcomere strain, confined to the plateau of the isometric tension-length relationship) were given at different velocities of lengthening (0f03-1f8sarcomere lengths s-1). Isotonic release to T. took place immediately after the end of the ramp, or 5-800 ms after the end of the largest ramp stretches. The length changes taking place after release were measured both at the fibre end and on a tendon-free segment of the fibre. The experiments were carried out at 4 and 14 'C. 4. After the elastic recoil of the undamped elastic elements, taking place during the fall in tension at the instant of the isotonic release, a well-defined shortening took place against T. (transient shortening against T.).5. The amplitude and time course of transient shortening against To were similar at the fibre end and in the segment, indicating that it is due to a property of the sarcomeres and not due to stress relaxation of the tendons.6. Transient shortening against To increased with sarcomere stretch amplitude up to about 8 nm per half-sarcomere independent of stretch velocity. 7. When a short delay (5-20 ms) was introduced between the end of the stretch and the isotonic release, the transient shortening against To did not change; after longer time delays, the transient shortening against T. decreased in amplitude.8. The velocity of transient shortening against To increased with temperature with a temperature coefficient, Qlo, of -2-5. 9. It is suggested that transient shortening against To results from the release of mechanical energy stored within the damped element of the cross-bridges. The crossbridges are brought into a state of greater potential energy not only during the ramp stretch, but also immediately afterwards, during the fast phase of stress relaxation.

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Section: Resultsmentioning

confidence: 99%

Storage and release of mechanical energy by contracting frog muscle fibres.

Cavagna

Heglund

Harry

et al. 1994

The Journal of Physiology

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“…Many studies of active lengthening are difficult to apply precisely to our data because the experimental conditions differ from those found for the ILPO. Typical studies of active lengthening lengthen fully active muscles or single above the optimal sarcomere length (Flitney and Hirst, 1978;Edman et al, 1978;Cavagna et al, 1981;Cavagna et al, 1986;Sugi and Tsuchiya, 1981;Takarada et al, 1997). We know of no study that has examined lengthening of muscle fibers under conditions similar to those we have described for the ILPO, i.e.…”

Section: Alternative Hypotheses To Explain Differential Active Lengthmentioning

confidence: 90%

Differential segmental strain during active lengthening in a large biarticular thigh muscle during running

Carr

Ellerby

Marsh

2011

Journal of Experimental Biology

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SUMMARYThe iliotibialis lateralis pars postacetabularis (ILPO) is the largest muscle in the hindlimb of the guinea fowl and is thought to play an important role during the stance phase of running, both absorbing and producing work. Using sonomicrometry and electromyography, we examined whether the ILPO experiences differential strain between proximal, central and distal portions of the posterior fascicles. When the ILPO is being lengthened while active, the distal portion was found to lengthen significantly more than either the proximal or central portions of the muscle. Our data support the hypothesis that the distal segment lengthened farther and faster because it began activity at shorter sarcomere lengths on the ascending limb of the length-tension curve. Probably because of the self-stabilizing effects of operating on the ascending limb of the length-tension curve, all segments reached the end of lengthening and started shortening at the same sarcomere length. During shortening, this similarity in sarcomere length among the segments was maintained, as predicted from force-velocity effects, and shortening strain was similar in all segments. The differential active strain during active lengthening is thus ultimately determined by differences in strain during the passive portion of the cycle. The sarcomere lengths of all segments of the fascicles were similar at the end of active shortening, but after the passive portion of the cycle the distal segment was shorter. Differential strain in the segments during the passive portion of the cycle may be caused by differential joint excursions at the knee and hip acting on the ends of the muscle and being transmitted differentially by the passive visco-elastic properties of the muscle. Alternatively, the differential passive strain could be due to the action of active or passive muscles in the thigh that transmit force to the IPLO in shear. Based on basic sarcomere dynamics we predict that differential strain is more likely to occur in muscles undergoing active lengthening at the beginning of contraction than those undergoing only shortening.

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“…Furthermore, the efficiency of external work production in kangaroos increases with speed suggesting an improved elastic storage and recovery as the force exerted on the ground increases [22]. It has been shown that force enhancement following muscle stretch has a transient character, i.e., it disappears rapidly at the end of stretching and, with it, the elastic energy stored within tendons and other undamped elastic elements [92]. This transient character of elastic storage and recovery may contribute to the observed decrease of the landing-takeoff asymmetry with running speed in humans.…”

Section: Factors Affecting the Elastic Storage Mechanismmentioning

confidence: 99%

Symmetry and Asymmetry in Bouncing Gaits

Cavagna

2010

Symmetry

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Abstract:In running, hopping and trotting gaits, the center of mass of the body oscillates each step below and above an equilibrium position where the vertical force on the ground equals body weight. In trotting and low speed human running, the average vertical acceleration of the center of mass during the lower part of the oscillation equals that of the upper part, the duration of the lower part equals that of the upper part and the step frequency equals the resonant frequency of the bouncing system: we define this as on-offground symmetric rebound. In hopping and high speed human running, the average vertical acceleration of the center of mass during the lower part of the oscillation exceeds that of the upper part, the duration of the upper part exceeds that of the lower part and the step frequency is lower than the resonant frequency of the bouncing system: we define this as on-off-ground asymmetric rebound. Here we examine the physical and physiological constraints resulting in this on-off-ground symmetry and asymmetry of the rebound. Furthermore, the average force exerted during the brake when the body decelerates downwards and forwards is greater than that exerted during the push when the body is reaccelerated upwards and forwards. This landing-takeoff asymmetry, which would be nil in the elastic rebound of the symmetric spring-mass model for running and hopping, suggests a less efficient elastic energy storage and recovery during the bouncing step. During hopping, running and trotting the landing-takeoff asymmetry and the mass-specific vertical stiffness are smaller in larger animals than in the smaller animals suggesting a more efficient rebound in larger animals.

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Mechanical transients initiated by ramp stretch and release to Po in frog muscle fibers

Cited by 40 publications

References 13 publications

Storage and release of mechanical energy by contracting frog muscle fibres.

Storage and release of mechanical energy by contracting frog muscle fibres.

Differential segmental strain during active lengthening in a large biarticular thigh muscle during running

Symmetry and Asymmetry in Bouncing Gaits

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