Article

Analysis of Lower Limb Asymmetries by Isokinetic and Vertical Jump Tests in Soccer Players

Laboratory of Sport Biomechanics, Federal University of Minas Gerais, Belo Horizonte, BRAZIL.
The Journal of Strength and Conditioning Research (Impact Factor: 1.86). 07/2012; 27(5). DOI: 10.1519/JSC.0b013e318265a3c8
Source: PubMed

ABSTRACT Assessment of lower extremity bilateral asymmetries in soccer players is important for both injury prevention and performance. The purpose of this investigation was to compare isokinetic knee extensor assessment of asymmetry with a more specific countermovement jump (CMJ). Forty-six male Brazilian professional soccer players participated in this study. The maximal power, maximal force and impulse were determined during CMJ as well as the total work and peak torque at 60/s, 180/s and 300/s during isokinetic leg extension, separately for each leg. Factor analysis was performed for all investigated variables, and the diagnostic concordance between different criteria was analyzed by McNemar's Chi test. The factor analysis showed that the isokinetic and CMJ tests were widely independent methods for the assessment of bilateral differences. Concordance of the diagnostic information could only be found between the maximal force during CMJ and the total work and peak torque at 180°/s and 300/s during isokinetic leg extension. Impulse and maximal power during countermovement jump on a double force platform appear to be appropriate additional variables for the identification of bilateral differences. Therefore, it might be pertinent to perform, in addition to isokinetic assessment, a vertical jump test on a force platform to assure widespread and reliable diagnostic information.

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    • "Since its inception in the late 1960s, it has become an essential part in sports sciences and physiotherapy being applied both in research and training studies as well as in rehabilitation (for review see [1] [2] [3] [4]). Isokinetic devices are used for training and testing purposes due to their unique contraction conditions [5] [6] [7] [8], rehabilitative and preventive application possibilities [9] [10] [11] [12] [13] [14] as well as their predictive power in relation to several sport-specific capabilities [15] [16] [17] [18] [19]. Reliability represents an important quality criterion of measurement instruments for research and performance diagnostics. "
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    ABSTRACT: Compare the ability of commonly used comparison models to detect neuromuscular asymmetries. A secondary purpose was to determine which neuromuscular task(s) has the greatest sensitivity to identify asymmetries based on the ASI (asymmetry index) calculation. Elite female youth basketball players (N = 29, age = 15.7 ± 1.34 y) performed the single leg countermovement jump in vertical, horizontal, and lateral directions, the star excursion balance test in the anterior, posteromedial, and posterolateral directions, and the sprint test with change of direction. Paired t-tests compared right and left limbs, the dominant (DL) and non-dominant (NDL) limbs, and the more/less skillful limbs. The coincident identification between the more skillful leg and the leg subjectively described as the DL was low for all of the tasks performed (35%-52%). There were significant differences between the more and less skillful legs for all tasks, while performances between the right and left limbs and DL and NDL differed significantly for only one task each. The largest ASI detected in this study was found in the vertical single leg countermovement jump (14.11%). The skillful limb model of comparison may be more useful than other models to detect neuromuscular asymmetries. Copyright © 2015 Elsevier Ltd. All rights reserved.
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