Cardiorespiratory fitness (CrF) is a strong predictor of health. The 20-m shuttle-run test is widely used to estimate CrF in children. However, it is not clear if it provides reliable data in adolescents with obesity.
PURPOSE: To compare CrF assessed by the 20-m shuttle-run test and a maximal graded exercise test (GXT) in adolescents with obesity.
METHODS: Thirty-seven adolescents (16 boys: 15 ± 2 y, 32.5 ± 2.9 kg·m^-2 and 41.9 ± 6.6 % fat and 21 girls: 15 ± 2 y, 34.6 ± 3.3 kg·m^-2 and 48.5 ± 8.5 % fat) underwent two CrF assessments on different days (7-days wash-out between). For the 20-m shuttle-run test, adolescents were instructed to run between two points separated by 20 meters at a predetermined pace that started at 8.5 km·h^-1 and increased by 0.5 km·h^-1 until the participant failed twice to keep up with an auditory signal or reached exhaustion. Maximum oxygen uptake (V̇O_2max) was estimated using Barnett and colleague’s equation. For the GXT, participants exercised on a treadmill with a speed that started at 3.0 km·h^-1 and increased by 1.0 km·h^-1 each minute until failure. During the GXT, V̇O₂ was measured using open circuit spirometry.
RESULTS: Estimated V̇O_2max was higher in the shuttle-run test (33.4 ± 4.6 ml·kg^-1·min^-1) compared to the GXT (24.6 ± 6.7 ml·kg^-1·min^-1, p<0.01). Estimated V̇O_2max obtained in the shuttle-run test was not related to V̇O_2max obtained in the GXT (rho=-0.03; p=0.85). However, the V̇O_2max obtained in GXT was associated with final speed (rho=0.58; p<0.01) and number of completed stages (rho=0.59; p<0.01) on the shuttle-run test.
CONCLUSIONS: Performance indicators from the 20-m shuttle-run test are significantly associated with directly measured V̇O2max. However, the predictive equation to estimate V̇O2max based on 20-m shuttle run test is not adequate for adolescents with obesity.