Intra- and Inter-Limb Strength Asymmetry in Soccer: A Comparison of Professional and Under-18 Players.

Chris Bishop,Giuseppe Coratella,Marco Beato

doi:10.3390/sports9090129

Chris Bishop, Giuseppe Coratella + Show 1 more

Open Access

https://doi.org/10.3390/sports9090129

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Abstract

(1) Background: the present study examined the isokinetic peak torque exerted by both knee extensors and flexors, anterior–posterior imbalance and the magnitude and direction of inter-limb asymmetry in professional and academy soccer players. (2) Methods: one hundred soccer players (professional = 50, elite academy = 50) volunteered to take part in this investigation. An isokinetic dynamometer was used to measure the knee extensor (quadriceps) and flexors muscle (hamstrings) torques of the limbs as well as inter-limb asymmetries—using a standard percentage difference equation. (3) Results: professional players exhibited significantly greater (effect size [ES] = large) strength levels in the quadriceps and hamstrings under both testing conditions, significantly higher (small to moderate) intra-limb ratio values for 60°·s−1 but not for the 300°·s−1 test condition, significantly (small to moderate) lower inter-limb asymmetry values for all test conditions, with the exception of the hamstrings at 60°·s−1 and the direction of asymmetry was poor to slight, indicating that limb dominance was rarely the same between groups. (4) Conclusions: this study shows that isokinetic assessments, i.e., peak torque exerted by both knee extensors and flexors and intra-limb ratio, and the subsequent inter-limb asymmetry, i.e., magnitude and direction, can differentiate between professional and academy soccer players.

Highlights

Soccer players are required to perform a combination of movements where lowerlimb strength and power are exerted maximally, such as jumps, sprints and changes in direction [1,2,3,4]
(4) Conclusions: this study shows that isokinetic assessments, i.e., peak torque exerted by both knee extensors and flexors and intra-limb ratio, and the subsequent inter-limb asymmetry, i.e., magnitude and direction, can differentiate between professional and academy soccer players
The present study examined the isokinetic peak torque exerted by both knee extensors and flexors in professional and academy soccer players

Summary

Introduction

Soccer players are required to perform a combination of movements where lowerlimb strength and power are exerted maximally, such as jumps, sprints and changes in direction [1,2,3,4]. Despite the varied motor skills required in soccer, strength is a critical physical quality that underpins successful performance in these tasks [5,6,7,8]. The same study observed that academy players had lower knee extensor and flexor strength than professional players [9]. These kinds of data may have implications for both on-field performance and injury risk [1,10]. Monitoring lower-limb strength over time could be helpful to develop the physical capacities of academy players by providing markers for the transition towards the professional level [3,9,11]

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Discussion

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