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THE TIME-COURSE OF VOLUNTARY AND ELECTRICALLY EVOKED MUSCLE PERFORMANCE
DURING AND AFTER STRETCH-SHORTENING EXERCISE IS DIFFERENT
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Albertas
Skurvydas ,
Gediminas Mamkus, Vilma Dudoniené, Sigitas Kamandulis, Dalia
Mickeviciene, Nerijus Masiulis, Aleksas Stanislovaitis and Vytautas
Streckis |
Laboratory of Human Motorics, Department of Applied Physiology and Health
Education, Lithuanian Academy of Physical Education, Kaunas, Lithuania.
| Received |
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28 March 2007 |
| Accepted |
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11
June 2007 |
| Published |
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01
December 2007 |
©
Journal of Sports Science and Medicine (2007) 6, 408- 416
| ABSTRACT |
| The aim of the study was to establish the dynamics of maximal
voluntary contraction force (MVCF), height of drop jump (DJ) and electrically
evoked quadriceps muscle force at different stimulation frequencies
during and after 100 DJs (stretch-shortening exercise, SSE). Healthy
untrained men (n = 11; age = 21.8 ± 1.7 years) participated in the
study. DJs were performed with 30 s intervals between jumps from the
height of 0.5 m with counter-movement to 90 degrees angle in the knee
and immediate maximal rebound. The force of the quadriceps muscle,
evoked by electrical stimulation at 1 Hz (Pt), 20 Hz (P20) and 100
Hz (P100) frequencies (electrically evoked performance, EEP), MVCF
and height of DJ (voluntary evoked performance, VEP) were established
during SSE (after 10, 50, 100 DJ) as well as at 1, 4, 8, 24, 48 and
72 h after SSE. Time-course of P20 and P100 during and after SSE was
time (ANOVA: p < 0.001) and frequency dependent (ANOVA: p <
0.001) The Pt, P20 and P100 decreased significantly (p < 0.01)
more than MVCF and H of DJ during SSE. At the beginning of SSE (during
1-10 DJs) P20 and P100 decreased significantly (p < 0.001) more
than during 11-50 and 51-100 DJs. There was a significant (p <
0.05) increase in Pt, P20 and P100 from 8 h to 48 h, whereas height
of DJ and MVCF significantly decreased at that time. In conclusion,
the differences in time course of VEP and EEP are most evident at
beginning of SSE, where VEP does not change as EEP decreases, and
within 8-48 hours after SSE, where VEP decreases as EEP increases.
KEY
WORDS: Drop jump, muscle damage, electrical stimulation, low
frequency fatigue.
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