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| Store and recoil of elastic energy
in slow and fast types of human skeletal muscles. |
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Bosco C, Tihanyi J,
Komi PV, Fekete G,
Apor P.
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| 1982 |
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| NCBI |
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Stretch-shortening cycle refers to the mechanical condition in
which store and recoil of elastic energy occur in the skeletal muscle.
This leads to a greater work output when compared to a simple shortening
contraction. The subjects performed vertical jumps with and without
preliminary counter-movement and with small and large knee angular
displacement. The results indicated that those subjects who had more
fast twitch (FT) fibers benefited more from the stretching phase performed
with high speed and short angular displacement. The amounts of elastic
energy stored in this phase were 30 and 26 N X kgBW-1, respectively,
for FT and slow twitch (ST) type subjects. The recoil of elastic energy
was proportional to the amount of energy storage. In large amplitude
jumps where transient period between stretch and shortening is long
the both types of subjects demonstrated similar amount of storage
of elastic energy (17 and 16 N X kgBW-1, respectively). However, the
re-use of this elastic energy was greater in ST group (24%) as compared
to the FT group (17%). The results can be interpreted through differences
in sarcomere crossbridge life times between fast and slow muscle fibers.
The slow type muscle may be able to retain the cross-bridge attachment
for a longer period of time and therefore it may utilize elastic energy
better in a slow type ballistic motion. |
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