Introduction: Pulmonary rehabilitation plays a central role in the management of chronic respiratory diseases, including chronic obstructive pulmonary disease (COPD), post-COVID syndrome, and asthma. Circuit training is a well-established method in COPD, but has been less studied in post-COVID and asthma. This study evaluated the effectiveness of a structured circuit training program on pulmonary function, exercise capacity, and dyspnea across these three groups. Methodology: A prospective, quasiexperimental study was conducted with 30 patients (15 COPD, 11 post-COVID, 4 asthma). Participants completed a 12-week supervised circuit training program, which was delivered four times per week in 60-min sessions. Assessments at baseline and post-intervention included spirometry (FEV1, FVC, TLC, IVC), six-minute walk distance (6MWD), and the modified Medical Research Council (mMRC) dyspnea score. Results: In COPD patients, FEV1 increased by 7.7% of the predicted value (P < 0.001), FVC by 5.7% (P < 0.01), and 6MWD by 59m (P < 0.01), with mMRC decreasing from 3.2 +- 0.8 to 1.4 +- 0.6 (P < 0.01). In post-COVID participants, FEV1 increased by 9.1% (P < 0.001), FVC by 6.6% (P < 0.001), and 6MWD by 82m (P < 0.01), while mMRC improved from 3.5 +- 0.9 to 1.4 +- 0.6 (P < 0.01). Asthma patients demonstrated a 4.9% increase in FEV1 (P 5 0.012), a 3.5% increase in FVC (P 5 0.045), and a 41-m increase in 6MWD (P < 0.01), with mMRC improving from 2.7 +- 0.7 to 1.5 +- 0.5 (P < 0.01). IVC improved in all groups (P <= 0.051). There were no adverse events; adherence exceeded 85%. Conclusion: Circuit training produced clinically meaningful spirometric improvements in COPD, as well as functional and symptomatic benefits across all groups. The findings support circuit training as a safe, feasible, and scalable modality in pulmonary rehabilitation for heterogeneous respiratory populations.  Kulcsszavak: pulmonary rehabilitation, circuit training, COPD, post-COVID, asthma, 6MWD, dyspnea