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Purpose: To examine the reliability of age-adapted submaximal Yo-Yo (Yo-Yosubmax) intermittent tests in untrained schoolchildren aged 9–16 years (n = 139; 72 boys and 67 girls) and within children with high and low percentage of body fat (%BF). Methods: Yo-Yo intermittent recovery level 1 children’s (YYIR1C), Yo-Yo intermittent endurance level 1 (YYIE1), and Yo-Yo intermittent endurance level 2 (YYIE2) tests were performed 7 days apart by 9- to 11-, 12- to 13-, and 14- to 16-year-old children, respectively. Reliability was tested for Yo-Yosubmax heart rate (HRsubmax), peak HR, and maximal distance. Results: HRsubmax typical errors of measurement (TEM) in YYIR1C, YYIE1, and YYIE2 were 2.2% (1.7%–2.9%), 2.4% (1.9%–3.3%), 1.9% (1.6%–2.5%) and 2.4% (1.9%–3.3%), 2.4% (1.9%–3.2%), 1.9% (1.5%–2.4%) for girls and boys, respectively. HRsubmax intraclass correlation coefficient values were good to excellent (.62–.87) in all age groups and in schoolchildren of different %BF. TEM for HRsubmax ranged from 2.1% to 2.3% in high and low %BF groups. Maximal distance intraclass correlation coefficients were excellent and TEM values ranged from 11% to 12% in both %BF groups. HRsubmax was moderately to largely associated (r = −.46 to −.64; P < .002) with Yo-Yo maximal distance across the age groups. Conclusion: Yo-Yosubmax tests are a reliable tool providing useful and sustainable aerobic performance testing in physical education, irrespective of individual %BF.
Póvoas is with the Research Center in Sports Sciences, Health Sciences and Human Development, CIDESD, University Institute of Maia, ISMAI, Maia, Portugal. Krustrup and Larsen are with the Department of Sports Science and Clinical Biomechanics, SDU Sport and Health Sciences Cluster (SHSC), University of Southern Denmark, Odense, Denmark. Krustrup is also with Sport and Health Sciences, University of Exeter, Exeter, United Kingdom. Castagna is with the School of Sport and Exercise Sciences, University of Rome Tor Vergata, Rome, Italy; and Fitness Training and Biomechanics Laboratory, Italian Football Federation, Technical Department, Coverciano (Florence), Italy. da Silva and Pereira are with the Research Centre in Physical Activity, Health and Leisure, Faculty of Sport, University of Porto, Porto, Portugal. Coelho-e-Silva is with the Faculty of Sports Science and Physical Education, University of Coimbra, Coimbra, Portugal.