Abstract
1. The force—velocity relationship and the stress—strain curve of the so-called series elastic component (s.e.c.) of frog sartorius, semitendinosus and gastrocnemius have been determined during shortening against a given force (isotonic quick-release) and at high speed (controlled release): (a) from a state of isometric contraction and (b) after stretching of the contracted muscle. In both cases the muscle was released from the same length: this was usually slightly greater than the muscle's resting length.
2. The muscle released immediately after being stretched is able to shorten against a constant force, P, equal to or even greater than the isometric force, P0, at the same length. When the force P applied to the muscle is reduced below P0 the velocity of shortening is greater after stretching, and the force—velocity curve is therefore shifted along the velocity axis: the shift is maximal when P is near to P0 and it decreases rapidly with decreasing P.
3. The extent of shortening of the s.e.c. required to make the force fall from P0 to zero is 50-100% greater when the muscle is released immediately after stretching than when it is released from a state of isometric contraction. This difference is found by using either the controlled release method or the isotonic quick-release method.
4. If a time interval is left between the end of stretching and the onset of shortening of the contracted muscle (controlled release method), the length change of the s.e.c., for a given fall of the force, is reduced and approaches that taking place when the muscle is released from a state of isometric contraction.
5. Curare does not affect the results described above, indicating that these do not depend on modification of the neuromuscular transmission.
6. It is concluded that stretching a contracted muscle modifies temporarily: (a) its elastic characteristics, as shown by the greater amount of mechanical energy released for a given fall of the force at the muscle's extremities, and (b) its contractile machinery, as it is suggested by the change of the force—velocity relationship.
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Selected References
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- ABBOTT B. C., AUBERT X. M. The force exerted by active striated muscle during and after change of length. J Physiol. 1952 May;117(1):77–86. [PMC free article] [PubMed] [Google Scholar]
- Cavagna G. A., Dusman B., Margaria R. Positive work done by a previously stretched muscle. J Appl Physiol. 1968 Jan;24(1):21–32. doi: 10.1152/jappl.1968.24.1.21. [DOI] [PubMed] [Google Scholar]
- Cavagna G. A. The series elastic component of frog gastrocnemius. J Physiol. 1970 Feb;206(2):257–262. doi: 10.1113/jphysiol.1970.sp009011. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Civan M. M., Podolsky R. J. Contraction kinetics of striated muscle fibres following quick changes in load. J Physiol. 1966 Jun;184(3):511–534. doi: 10.1113/jphysiol.1966.sp007929. [DOI] [PMC free article] [PubMed] [Google Scholar]
- HILL A. V. The series elastic component of muscle. Proc R Soc Lond B Biol Sci. 1950 Jul 24;137(887):273–280. doi: 10.1098/rspb.1950.0035. [DOI] [PubMed] [Google Scholar]
- JEWELL B. R., WILKIE D. R. An analysis of the mechanical components in frog's striated muscle. J Physiol. 1958 Oct 31;143(3):515–540. doi: 10.1113/jphysiol.1958.sp006075. [DOI] [PMC free article] [PubMed] [Google Scholar]
- WILKIE D. R. Measurement of the series elastic component at various times during a single muscle twitch. J Physiol. 1956 Dec 28;134(3):527–530. doi: 10.1113/jphysiol.1956.sp005662. [DOI] [PMC free article] [PubMed] [Google Scholar]