Importance of Reactive Agility and Change of Direction Speed in Differentiating Performance Levels in Junior Soccer Players: Reliability and Validity of Newly Developed Soccer-Specific Tests.

Haris Pojskic,Ognjen Uljevic,Ivan Jukic,Erik Åslin,Miodrag Spasic,Damir Sekulic,Ante Krolo

doi:10.3389/fphys.2018.00506

Haris Pojskic, Ognjen Uljevic + Show 5 more

Open Access

https://doi.org/10.3389/fphys.2018.00506

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Abstract

Agility is a significant determinant of success in soccer; however, studies have rarely presented and evaluated soccer-specific tests of reactive agility (S_RAG) and non-reactive agility (change of direction speed – S_CODS) or their applicability in this sport. The aim of this study was to define the reliability and validity of newly developed tests of the S_RAG and S_CODS to discriminate between the performance levels of junior soccer players. The study consisted of 20 players who were involved at the highest national competitive rank (all males; age: 17.0 ± 0.9 years), divided into three playing positions (defenders, midfielders, and forwards) and two performance levels (U17 and U19). Variables included body mass (BM), body height, body fat percentage, 20-m sprint, squat jump, countermovement jump, reactive-strength-index, unilateral jump, 1RM-back-squat, S_CODS, and three protocols of S_RAG. The reliabilities of the S_RAG and S_CODS were appropriate to high (ICC: 0.70 to 0.92), with the strongest reliability evidenced for the S_CODS. The S_CODS and S_RAG shared 25–40% of the common variance. Playing positions significantly differed in BM (large effect-size differences [ES]; midfielders were lightest) and 1RM-back-squat (large ES; lowest results in midfielders). The performance levels significantly differed in age and experience in soccer; U19 achieved better results in the S_CODS (t-test: 3.61, p < 0.05, large ES) and two S_RAG protocols (t-test: 2.14 and 2.41, p < 0.05, moderate ES). Newly developed tests of soccer-specific agility are applicable to differentiate U17 and U19 players. Coaches who work with young soccer athletes should be informed that the development of soccer-specific CODS and RAG in this age is mostly dependent on training of the specific motor proficiency.

Highlights

Agility has been defined as “a rapid whole-body movement with change of speed or direction in response to a stimulus” (Sheppard and Young, 2006)
The results showed appropriate reliability of all measurement tools assessed; the newly constructed reactive-agility test was the best predictor of player performance level
No significant differences were identified among the three playing positions

Summary

Introduction

Agility has been defined as “a rapid whole-body movement with change of speed or direction in response to a stimulus” (Sheppard and Young, 2006). This definition is based on a model that separates agility into two components, the change of direction speed and perceptual and decision-making processes. On the basis of a previously described idea of the existence of two capacities in agility, two independent types of agility performances are identified, including pre-planned agility (closed skill agility, change of direction speed – CODS) and non-planned agility (open skill agility, reactive agility – RAG) (Gabbett et al, 2008; Sekulic et al, 2014a; Spasic et al, 2015). Studies to date have shown relatively low correlations between tests of these two capacities; the independent assessment and development of these qualities are of substantial importance (Pehar et al, 2017b)

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