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| The effect of fatigue on store and
re-use of elastic energy in slow and fast types of human skeletal
muscle. |
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Bosco C, Tihanyi J,
Latteri F, Fekete G,
Apor P, Rusko H. |
| 1986 |
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| NCBI |
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Stretch-shortening exercises are characterized by enhancement of
performance when compared to the work output performed in shortening
conditions. There is evidence that fast subjects are unable to re-use
great amounts of elastic energy during stretch-shortening cycles performed
with slow stretching speed and large stretching length. In the present
study, 14 subjects possessing different fibre types in m. vastus lateralis
performed vertical jumps with and without preliminary countermovement
and with large angular displacement and slow stretching speed The
jumping tests were executed before and immediately after fatigue induced
by short intense exercises (60 s of continuous rebound jumping). The
results indicated that the percentage of re-use of elastic energy
was more pronounced in slow subjects compared to fast ones during
the test performed before fatigue (28.3% vs. 22.8%). In contrast fast
subjects demonstrated a greater percentage re-use of elastic energy
than slow ones after fatigue (32% vs. 22.5%). Similarly, the negative
relationship observed before fatigue, between the percentage of re-use
of elastic energy and percentage of fast twitch fibres (r = 0.50,
n = 14, P less than 0.05), was reversed after fatigue (r = 0.55, n
= 14, P less than 0.05). The results can be interpreted through differences
in sarcomere cross-bridges life-times between fast and slow twitch
muscle fibres. The slow twitch-type muscle fibre may be able to retain
the cross-bridge attachment for a longer period of time during no
fatigued conditions, and therefore it may utilize elastic energy better
in slow type ballistic motion. On the other hand, fast twitch type
muscle fibres are more affected by fatigue, which might have induced
a remarkable decrease of the cross-bridge attachment detachment cycle.
Decrease of the cross-bridge rate cycle might allow fast twitch-type
muscle fibres to retain longer the elastic energy stored during the
stretching phase and then re-use it during positive phase. |
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