Stretch shortening cycle

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A stretch-shortening cycle (SSC) is an active stretch (eccentric contraction) of a muscle followed by an immediate shortening (concentric contraction) of that same muscle.

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Research studies

The increased performance benefit associated with muscle contractions that take place during SSCs has been the focus of much research in order to determine the true nature of this enhancement. At present, there is some debate as to where and how this performance enhancement takes place. It has been postulated that elastic structures in series with the contractile component can store energy like a spring after being forcibly stretched. [1] Since the length of the tendon increases due to the active stretch phase, if the series elastic component acts as a spring, it would therefore be storing more potential energy. This energy would be released as the tendon shortened. Thus, the recoil of the tendon during the shortening phase of the movement would result in a more efficient movement than one in which no energy had been stored. [2] This research is further supported by Roberts et al. [3]

However, other studies have found that removing portions of these series-elastic components (by way of tendon length reduction) had little effect on muscle performance. [4]

Studies on turkeys have, nevertheless, shown that during SSC, a performance enhancement associated with elastic energy storage still takes place but it is thought that the aponeurosis could be a major source of energy storage (Roleveld et al., 1994). The contractile component itself has also been associated with the ability to increase contractile performance through muscle potentiation [5] while other studies have found that this ability is quite limited and unable to account for such enhancements (Lensel and Goubel, 1987, Lensel-Corbeil and Goubel, 1990; Ettema and Huijing, 1989).

Community agreement

The results of these often contradictory studies have been associated with improved efficiencies for human or animal movements such as counter-movement jumps and running. [6] [7] [8] However it is still not established why and how this enhancement takes place. It is one of the underlying mechanisms of plyometric training.

See also

Related Research Articles

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Sarcomere Repeating unit of a myofibril in a muscle cell

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Elastic mechanisms in animals are very important in the movement of vertebrate animals. The muscles that control vertebrate locomotion are affiliated with tissues that are springy, such as tendons, which lie within the muscles and connective tissue. A spring can be a mechanism for different actions involved in hopping, running, walking, and serve in other diverse functions such as metabolic energy conservation, attenuation of muscle power production, and amplification of muscle power production.

References

  1. ↑ R. McNeill Alexander (2002). Principles of Animal Locomotion. Princeton University Press. ISBN   0-691-08678-8.
  2. ↑ A. L. Hof and J. W. van den Berg (1986). "How much energy can be stored in human muscle elasticity?". Movement Science. 5 (2): 107–114. doi:10.1016/0167-9457(86)90018-7.
  3. ↑ Thomas J. Roberts, Richard L. Marsh, Peter G. Weyand and C. Richard Taylor (1997). "Muscular Force in Running Turkeys: The Economy of Minimizing Work". Science. 275 (5303): 1113–1115. doi:10.1126/science.275.5303.1113. PMID   9027309. S2CID   27385646.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  4. ↑ R. Baratta & M. Solomonow (1991). "The effect of tendon viscoelastic stiffness on the dynamic performance of isometric muscle". Journal of Biomechanics. 24 (2): 109–116. doi:10.1016/0021-9290(91)90355-Q. PMID   2037610.
  5. ↑ Cavagna G, Dusman B, Margaria R (1968). "Positive work done by a previously stretched muscle". Journal of Applied Physiology . 24 (1): 21–32. doi:10.1152/jappl.1968.24.1.21. PMID   5635766.
  6. ↑ Komi, P. V. (1984). "Physiological and biomechanical correlates of muscle function: effects of muscle structure and stretch-shortening cycle on force and speed". Exercise and Sport Sciences Reviews. 12: 81–121. doi:10.1249/00003677-198401000-00006. ISSN   0091-6331. PMID   6376140. S2CID   29976682.
  7. ↑ Asmussen, E.; Bonde-Petersen, F. (July 1974). "Storage of elastic energy in skeletal muscles in man". Acta Physiologica Scandinavica. 91 (3): 385–392. doi:10.1111/j.1748-1716.1974.tb05693.x. ISSN   0001-6772. PMID   4846332.
  8. ↑ Cavagna, Giovanni A. (1977). "Storage and utilization of elastic energy in skeletal muscle". Exercise and Sport Sciences Reviews. 5 (1): 89–130. doi:10.1249/00003677-197700050-00004. PMID   99306. S2CID   33617675.
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