TY - JOUR T1 - The 20 m shuttle run is not a valid test of cardiorespiratory fitness in boys aged 11–14 years JF - BMJ Open Sport & Exercise Medicine JO - BMJ OPEN SP EX MED DO - 10.1136/bmjsem-2019-000627 VL - 5 IS - 1 SP - e000627 AU - Jo Welsman AU - Neil Armstrong Y1 - 2019/12/01 UR - http://bmjopensem.bmj.com/content/5/1/e000627.abstract N2 - Objectives The 20 m shuttle run test (20mSRT) is used to estimate cardiorespiratory fitness (CRF) through the prediction of peak oxygen uptake ( ), but its validity as a measure of CRF during childhood and adolescence is questionable. This study examined the validity of the 20mSRT to predict peak .Methods Peak was measured during treadmill running. Log-linear regression was used to correct peak for body mass and sum of skinfolds plus age. Boys completed the 20mSRT under standardised conditions. Maximum speed (km/h) was used with age to predict peak using the equation developed by Léger et al. Validity was examined from linear regression methods and limits of agreement (LoA). Relationships between 20mSRT performance and allometrically adjusted peak , and predicted per cent fat were examined.Results The sample comprised 76 boys aged 11–14 years. Predicted and measured mass-related peak (mL/kg/min) shared common variance of 32%. LoA revealed that measured peak ranged from 15% below to 25% above predicted peak . There were no significant relationships (p>0.05) between predicted peak and measured peak adjusted for mass, age and skinfold thicknesses. Adjusted for body mass and age, peak was not significantly related (p>0.05) to 20mSRT final speed but a weak, statistically significant (r=0.24, p<0.05) relationship was found with peak adjusted for mass and fatness. Predicted per cent fat was negatively correlated with 20mSRT speed (r=−0.61, p<0.001).Conclusions The 20mSRT reflects fatness rather than CRF and has poor validity grounded in its flawed estimation and interpretation of peak in mL/kg/min. ER -