Reliability and Factorial Validity of Non-Specific and Tennis-Specific Pre-Planned Agility Tests; Preliminary Analysis

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Damir Sekulic, Ognjen Uljevic, Mia Peric, Miodrag Spasic, Miran Kondric

Agility is an important quality in tennis, yet there is an evident lack of studies focussing on the applicability of tennis-specific agility performances and comparing them to equivalent non-specific agility performances. The aim of this study was to evaluate the reliability and factorial validity of three tests of pre-planned agility, performed in specific (with a tennis racquet) and non-specific (without a tennis racquet) conditions. The sample consisted of 33 tennis players (13 males and 20 females; age: 18.3 ± 1.1 years and 18.6 ± 1.3 years; body height: 185.4 ± 51 cm and 169.3 ± 4.2 cm, 74.0 ± 4.4 kg and 61.2 ± 3.1 kg, respectively). The variables comprised three agility tests: a 20-yard test, a T-test and the Illinois test, all performed in both specific and non-specific conditions. Between-subject and within-subject reliability were found to be high (Cronbach Alpha: 0.93 to 0.98; Coefficient of Variation: 3 to 8%), with better within-subject reliability and stability of the measurement for specific tests. Pearson’s product moment correlations between the non-specific and specific agility performances were high (r ≥0.84), while factor analysis extracted only one significant latent dimension on the basis of the Guttman-Kaiser criterion. The results of the 20-yard test were better when the test was conducted in the specific conditions (t-test = 2.66; p < 0.05). For the Illinois test, superior results were recorded in the non-specific conditions (t-test = 2.96; p < 0.05), which can be explained by the test duration (about 20 s) and non-specific locomotion forms such as rotational movements. Considering the findings of the present study, when testing tennis-specific pre-planned agility, we suggest using tests of short duration (less than 10 s) and sport-specific types of locomotion.
DOI: 10.1515/hukin-2017-0010
Key words
between-subject reliability, within-subject reliability, factor analysis, change of direction speed, applicability

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