The isokinetic strength profile of elite soccer players according to playing position.

Robert Śliwowski,Monika Grygorowicz,Radosław Hojszyk,Łukasz Jadczak,Antoine Nordez

doi:10.1371/journal.pone.0182177

Robert Śliwowski, Monika Grygorowicz + Show 3 more

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https://doi.org/10.1371/journal.pone.0182177

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Abstract

The aim of this study was to compare isokinetic strength performance profiles in elite soccer players across different field positions. A total of 111 elite international players of Polish Ekstraklasa (the top division in Poland) were examined during the 2010–2015 seasons. The players were classified into six positional roles: central defenders (CD), external defenders (ED), central midfielders (CM), external midfielders (EM), forwards (F), and goalkeepers (G). The concentric isokinetic strength (peak torque [PT] of quadriceps and hamstrings, H/Q ratios) was calculated for the dominant leg and the non-dominant leg at angular velocity of 1.05 rad ·s–1, whereas to assess isokinetic muscle endurance, the total work [TW] at angular velocity of 4.19 rad ·s–1, was taken into consideration. The results showed that isokinetic strength performance varies significantly among players in different playing positions. The analysis of PT for quadriceps (PT-Q) and hamstrings (PT-H) generally showed that the goalkeepers and central midfielders had lower strength levels compared to other playing positions. In the case of PT-H and hamstring/quadricep (H/Q) peak torque ratios, statistically significant differences were also noted for the legs, where mean values noted for the dominant leg were higher than for the non-dominant leg. For TW for quadriceps (TW-Q) and hamstrings (TW-H), statistically significant differences were noted only between playing positions. TW-Q values for goalkeepers were lower than for central defenders and external midfielders. TW-H values for goalkeepers were lower than for central midfielders, central defenders and external midfielders. This study showed that specific functional activity of players in individual positions on the field influences the varied profile of isokinetic strength performance.

Highlights

Measurement of muscle strength is an important factor in the evaluation and prediction of muscular condition in addition to functional capacity [1]
In the case of PT-H and hamstring/quadricep (H/Q) peak torque ratios, statistically significant differences were noted for the legs, where mean values noted for the dominant leg were higher than for the non-dominant leg
Central defenders are significantly heavier than external midfielders (p < 0.0001), external defenders (p = 0.0128), and central midfielders (p = 0.0065)

Summary

Introduction

Measurement of muscle strength is an important factor in the evaluation and prediction of muscular condition in addition to functional capacity [1]. A lot of research supports this concept [2,3,4]. Isokinetic peak torque (PT) assessment is one of the most commonly applied methods of evaluation of muscle strength of the lower extremities in soccer [5,6,7]. Knee flexor and extensor muscle strength and the hamstring-to-quadricep ratio have been identified as important criteria to analyse the risk of lower extremity injuries [2, 6, 8].

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