Abstract Background To help elderly patients with severe or very severe chronic obstructive pulmonary disease (COPD) with pulmonary rehabilitation, we have developed Zheng's supine rehabilitation exercise (ZSRE). Currently, none of the terminal or critically ill patients with severe exercise limitation can complete the 6‐min walking distance (6MWD) and cardiopulmonary exercise testing (CPET). Methods In this study, we discuss the definition of the standardized 3‐min simulated pedal motion (3MSPM) test and its operational specifications. Also, we evaluate the minimal clinically important difference (MCID) value of the 3MSPM. Results The results showed that the mMRC score of COPD patients with acute exacerbation of dyspnea was progressively reduced from the second day of respiratory rehabilitation, and the difference between the first and seventh days was statistically significant (p