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JOURNAL
OF
SPORTS SCIENCE &
MEDICINE
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Research
article
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LOWER LIMB STRENGTH IN PROFESSIONAL SOCCER PLAYERS: PROFILE, ASYMMETRY, AND TRAINING AGE |
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Konstantinos Fousekis1,2  ,
Elias Tsepis2 and George Vagenas1 |
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1Quantitative Analysis & Kinesiology Research, Department of Physical Education & Sports Science, University of Athens, Greece, 2Biomechanics and Sports Injuries Laboratory, Department of Physiotherapy, Technological Educational Institute of Patras, Branch Department of Aigion, Greece |
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© Journal of Sports Science and Medicine (2010) 9, 364 - 373 |
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| ABSTRACT | |||
| Kicking and cutting skills in soccer are clearly unilateral, require
asymmetrical motor patterns and lead to the development of asymmetrical
adaptations in the musculoskeletal function of the lower limbs. Assuming
that these adaptations constitute a chronicity-dependent process, this study
examined the effects of professional training age (PTA) on the composite
strength profile of the knee and ankle joint in soccer players. One hundred
soccer players (n=100) with short (5-7 years), intermediate (8-10 years)
and long (>11 years) PTA were tested bilaterally for isokinetic concentric
and eccentric strength of the knee and ankle muscles. Knee flexion-extension
was tested concentrically at 60°, 180° and 300 °/sec and eccentrically at
60° and 180 °/sec. Ankle dorsal and plantar flexions were tested at 60 °/sec
for both the concentric and eccentric mode of action. Bilaterally averaged
muscle strength [(R+L)/2] increased significantly from short training age
to intermediate and stabilized afterwards. These strength adaptations were
mainly observed at the concentric function of knee extensors at 60°/sec
(p = 0. 023), knee flexors at 60°/sec (p = 0.042) and 180°/sec (p = 0.036),
and ankle plantar flexors at 60o/sec (p = 0.044). A linear trend of increase
in isokinetic strength with PTA level was observed for the eccentric strength
of knee flexors at 60°/sec (p = 0.02) and 180°/sec (p = 0.03). Directional
(R/L) asymmetries decreased with PTA, with this being mainly expressed in
the concentric function of knee flexors at 180°/sec (p = 0.04) and at 300
°/sec (p = 0.03). These findings confirm the hypothesis of asymmetry in
the strength adaptations that take place at the knee and ankle joint of
soccer players mainly along with short and intermediate PTA. Players with
a longer PTA seem to adopt a more balanced use of their lower extremities
to cope with previously developed musculoskeletal asymmetries and possibly
reduce injury risk. This has certain implications regarding proper training
and injury prevention in relation to professional experience in soccer.
Key words: Soccer, isokinetic strength, asymmetries, training-age. |
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