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Background & aim: Obesity and asthma, are cardiorespiratory changes that could affect the airways and may play a role in occurrence of symptoms during exercise. However, there is little information about the effect of high and low humidity on cardiorespiratory factor in obese children with asthma during progressive aerobic activity. Methods: The present case-control study was carried out with ten obese asthmatic children and fifteen healthy children who performed an exercise protocol in different environments (relative humidity 65 ± 5% versus 35 ± 5%). During exercise, cardiorespiratory parameters were controlled using K4B2. Heart rate, systolic blood pressure and double product were measured with a digital sphygmomanometer and stethoscope polar. Data were analyzed with dependent T test and ANOVA with repeated measures analysis. Results: A significant increase was detected in the markers of HR, SP and DP after exercise in obese children with asthma and healthy children (P< 0.005). However, indexes of cardiorespiratory and exhaustion was significantly higher in obese children with asthma and healthy during exercise in the environment with 65 ± 5% relative humidity, as compared to 35 ± 5% relative humidity. Conclusion: These results indicated that cardiorespiratory function in children with asthma and healthy children were different. Cardiorespiratory responses to exercise in children are influenced by environmental conditions such as humidity, so that humidity has a negative impact on the duration of the activity and load on the heart muscle.