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JOURNAL
OF
SPORTS SCIENCE &
MEDICINE
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Research
article
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PRE-ACTIVITY MODULATION OF LOWER EXTREMITY MUSCLES WITHIN DIFFERENT TYPES AND HEIGHTS OF DEEP JUMP |
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Vladimir Mrdakovic, Dusko B. Ilic  ,
Nenad Jankovic, Zeljko Rajkovic and Djordje Stefanovic |
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Department of Biomechanics and Motor Control, Faculty of Sport and Physical Education, University of Belgrade, Belgrade, Serbia |
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© Journal of Sports Science and Medicine (2008) 7, 269 - 278 Search Google Scholar for Citing Articles |
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| ABSTRACT | |||
| The purpose of this study was to determine modulation of pre-
activity related to different types and heights of deep jump. Sixteen male
soccer players without experience in deep jumps training (the national competition;
15.0 ± 0.5yrs; weight 61.9 ± 6.1kg; height 1.77 ± 0.07m), who participated
in the study, performed three types of deep jump (bounce landing, counter
landing, and bounce drop jump) from three different heights (40cm, 60cm,
and 80cm). Surface EMG device (1000Hz) was used to estimate muscle activity
(maximal amplitude of EMG - AmaxEMG; integral EMG signal - iEMG) of five
muscles (mm.gastrocnemii, m.soleus, m.tibialis anterior, m.vastus lateralis)
within 150ms before touchdown. All the muscles, except m. gastrocnemius
medialis, showed systematic increase in pre-activity when platform height
was raised. For most of the lower extremity muscles, the most significant
differences were between values of pre-activity obtained for 40 cm and 80
cm platforms. While the amount of muscle pre-activity in deep jumps from
the heights above and beneath the optimal one did not differ significantly
from that generated in deep jumps from the optimal drop height of 60 cm,
the patterns of muscle pre-activity obtained for the heights above the optimal
one did differ from those obtained for the optimal drop height. That suggests
that deep jumps from the heights above the optimal one do not seem to be
an adequate exercise for adjusting muscle activity for the impact. Muscle
pre-activity in bounce drop jumps differed significantly from that in counter
landing and bounce landing respectively, which should indicate that a higher
amount of pre-activity generated during bounce drop jumps was used for performing
take-offs. As this study included the subjects who were not familiar with
deep jumps training, the prospective studies should reveal the results of
athletes with previous experience.
Key words: Electromyography, programmed muscle activity, landings, drop jumps. |
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