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JOURNAL
OF
SPORTS SCIENCE &
MEDICINE
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Research
article
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ANALYSIS OF THE VERTICAL GROUND REACTION FORCES AND TEMPORAL FACTORS IN THE LANDING PHASE OF A COUNTERMOVEMENT JUMP |
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Daniel Rojano Ortega  ,
Elisabeth C. Rodríguez Bíes and Francisco J. Berral de la Rosa |
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Department of Informatics and Sports, University of Pablo de Olavide, Sevilla, Spain |
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© Journal of Sports Science and Medicine (2010) 9, 282 - 287 |
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| ABSTRACT | |||
| In most common bilateral landings of vertical jumps, there are
two peak forces (F1 and F2) in the force-time curve. The combination of
these peak forces and the high frequency of jumps during sports produce
a large amount of stress in the joints of the lower limbs which can be determinant
of injury. The aim of this study was to find possible relationships between
the jump height and F1 and F2, between F1 and F2 themselves, and between
F1, F2, the time they appear (T1 and T2, respectively) and the length of
the impact absorption phase (T). Thirty semi-professional football players
made five countermovement jumps and the highest jump of each player was
analyzed. They were instructed to perform the jumps with maximum effort
and to land first with the balls of their feet and then with their heels.
All the data were collected using a Kistler Quattro Jump force plate with
a sample rate of 500 Hz. Quattro Jump Software, v.1.0.9.0., was used. There
was neither significant correlation between T1 and F1 nor between T1 and
F2. There was a significant positive correlation between flight height (FH)
and F1 (r = 0.584, p = 0.01) but no significant correlation between FH and
F2. A significant positive correlation between F1 and T2 (r = 0.418, p <
0.05) and a significant negative correlation between F2 and T2 (r = -0.406,
p < 0.05) were also found. There is a significant negative correlation
between T2 and T (r = -0. 443, p < 0.05). T1 has a little effect in the
impact absorption process. F1 increases with increasing T2 but F2 decreases
with increasing T2. Besides, increasing T2, with the objective of decreasing
F2, makes the whole impact absorption shorter and the jump landing faster.
Key words: Impact absorption, peak forces, vertical jump, injuries. |
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