The 20 m shuttle run is not a valid test of cardiorespiratory fitness in boys aged 11–14 years

Objectives The 20 m shuttle run test (20mSRT) is used to estimate cardiorespiratory fitness (CRF) through the prediction of peak oxygen uptake (V˙O2), 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 V˙O2 .Methods Peak V˙O2 was measured during treadmill running. Log-linear regression was used to correct peak V˙O2 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 V˙O2 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 V˙O2, and predicted per cent fat were examined.Results The sample comprised 76 boys aged 11–14 years. Predicted and measured mass-related peak V˙O2 (mL/kg/min) shared common variance of 32%. LoA revealed that measured peak V˙O2 ranged from 15% below to 25% above predicted peak V˙O2 . There were no significant relationships (p>0.05) between predicted peak V˙O2 and measured peak V˙O2 adjusted for mass, age and skinfold thicknesses. Adjusted for body mass and age, peak V˙O2 was not significantly related (p>0.05) to 20mSRT final speed but a weak, statistically significant (r=0.24, p