The present study aimed at assessing air way resistance indexes that include FEV1 (Force expiration Volume in one second), FVC (Forced vital capacity) and FEV1/FVC and exercise-induced asthma (EIA) after one session of sub maximal incremental aerobic exercise. Fifty healthy male subjects (age 19-26) from the faculty of Physical Education, University of Shahid Chamran served as the participants of the study. They were randomly assigned to either exercise or control groups. Body height, body mass and pulmonary factors were measured in the pre-test conditions. The study protocol included a sub maximal incremental Astrand - Rhyming test on an ergocycle. After performing this test by the exercise group, FEV1, FVC and FEV1/FVC, were measured again for both groups and compared with pre test evaluations. The data were analyzed through descriptive and inferential statistics (dependent and independent t test). Results showed that there was a significant difference in FEV1 between the two groups after the exercise protocol (p ≤ 0.05). There was no significant difference in FVC between the two groups after exercise, and a significant difference was registered in FEV1 and FEV1/FVC between pre-test and post-test results in the group that performed the aerobic test protocol (p ≤ 0.05). Our results indicate that one sub maximal incremental aerobic exercise session causes a significant change in FEV1 and FEV1/FVC, and causes exercise-induced asthma.