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PURPOSE Whether modified shuttle teste (MST) achieves maximal effort in children and adolescents with asthma is unclear. The aim was to compare the physiological responses of MST to the cardiopulmonary exercise test (CPET) in pediatric patients with asthma, to observe its convergent validity. PATIENTS AND METHODS cross sectional study, volunteers with asthma (6 to 17 years of age) under regular treatment. The MST is an external-paced test, and the participants were allowed to walk/run. CPET was performed on a cycle ergometer to compare with MST. Gas exchange (VO2 , VCO2 , and VE) and heart rate (HR) were the outcomes, and continuously assessed in both tests. RESULTS 47 volunteers were included, normal lung function FEV1/FVC 88.6 (7.7). VO2peak was higher at MST (2.0 ± 0.6 L/min) compared to CPET (1.6 ± 0.5 L/min), p< 0.001. Similar to VE at MST (50 ± 16 L/min) vs at CPET (40 ± 13 L/min), and VCO2 , at MST (2.1 ± 0.8 L/min) vs CPET (1.7 ± 0.6 L/min), p < 0.001. HR was also higher at MST (94 ± 6%pred) vs CPET (87 ± 8%pred), p=0.002. VO2peak in MST correlated to the CPET (r = 0.78, p < 0.001). The ICC of VO2peak between tests was 0.73 (0.06 - 0.89), p<0.001, and VO2peak Bland-Altman analysis showed bias of 0.46L/min. CONCLUSION the MST showed maximal physiologic response in children and adolescents with asthma. It is valid test, and can be used as an alternative to evaluate exercise capacity. This article is protected by copyright. All rights reserved.