title: Reliability and validity of Yo-Yo tests in 9- to 16-year-old football players and matched non-sports active schoolboys.
abstract: The purpose of this study was to examine the test-retest reliability and construct validity of three age-adapted Yo-Yo intermittent tests in football players aged 9-16 years (n = 70) and in age-matched non-sports active boys (n = 72). Within 7 days, each participant performed two repetitions of an age-related intensity-adapted Yo-Yo intermittent test, i.e. the Yo-Yo intermittent recovery level 1 children's test for 9- to 11-year-olds; the Yo-Yo intermittent endurance level 1 for 12- to 13-year-olds and the Yo-Yo intermittent endurance level 2 test for 14- to 16-year-olds. Peak heart rate (HRpeak) was determined for all tests. The distance covered in the tests was 57% (1098 ± 680 vs. 700 ± 272 m), 119% (2325 ± 778 vs. 1062 ± 285 m) and 238% (1743 ± 460 vs. 515 ± 113 m) higher (p ≤ .016), respectively for football-trained than for non-sports active boys aged 9-11, 12-13 and 14-16 years. The typical errors of measurement for Yo-Yo distance, expressed as a percentage of the coefficient of variation (confidence interval), were 11.1% (9.0-14.7%), 10.1% (8.1-13.7%) and 8.5% (6.7-11.7%) for football players aged 9-11, 12-13 and 14-16 years, respectively, with corresponding values of 9.3% (7.4-12.8%), 10.2% (8.1-14.0%) and 8.5% (6.8-11.3%) for non-sports active boys. Intraclass correlation coefficient values for test-retest were excellent in both groups (range: 0.844-0.981). Relative HRpeak did not differ significantly between the groups in test and retest. In conclusion, Yo-Yo intermittent test performances and HRpeak are reliable for 9- to 16-year-old footballers and non-sports active boys. Additionally, performances of the three Yo-Yo tests were seemingly better for football-trained than for non-sports active boys, providing evidence of construct validity.
authors.affiliation: a Research Center in Sports Sciences, Health Sciences and Human Development, CIDESD , University Institute of Maia, ISMAI , Maia , Portugal.
authors.forename: Susana C A
authors.initials: SC
authors.lastname: Póvoas
authors.affiliation: b Fitness Training and Biomechanics Laboratory, Italian Football Federation, Technical Department , Coverciano (Florence), Italy.|c School of Sport and Exercise Sciences , University of Rome Tor Vergata , Rome , Italy.
authors.forename: Carlo
authors.initials: C
authors.lastname: Castagna
authors.affiliation: d Centre of Research, Education, Innovation and Intervention in Sport , Faculty of Sport, University of Porto , Portugal.
authors.forename: José M C
authors.initials: JM
authors.lastname: Soares
authors.affiliation: e Research Centre in Physical Activity, Health and Leisure , Faculty of Sport, University of Porto , Portugal.|f Department of Physical Education and Sport Sciences, University Institute of Maia, ISMAI , Maia , Portugal.
authors.forename: Pedro M R
authors.initials: PM
authors.lastname: Silva
authors.affiliation: f Department of Physical Education and Sport Sciences, University Institute of Maia, ISMAI , Maia , Portugal.
authors.forename: Mariana V M F
authors.initials: MV
authors.lastname: Lopes
authors.affiliation: g Sport and Health Sciences, College of Life and Environmental Sciences , University of Exeter , Exeter , United Kingdom.|h Copenhagen Centre for Team Sport and Health, Department of Nutrition, Exercise and Sports , University of Copenhagen , Copenhagen , Denmark.
authors.forename: Peter
authors.initials: P
authors.lastname: Krustrup
mesh_terms: D000293:Adolescent; D054874:Athletic Performance / Q000502:physiology*; D002648:Child; D005080:Exercise Test / Q000379:methods / Q000592:standards; D005538:Football / Q000502:physiology*; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D015203:Reproducibility of Results
keywords: HIIT; Reliability; aerobic endurance; heart rate; intense intermittent exercise; youth football