Researchers developed a non-invasive technique to diagnose and classify chronic obstructive pulmonary disease (COPD) using electromyography (EMG) signals from the sternomastoid muscle during respiration. They analyzed EMG signals in the time, frequency, and time-frequency domains, and developed an onset detection algorithm and conduction velocity measure that improved COPD detection accuracy to 98.61%. Researchers also used continuous wavelet transform analysis at specific frequencies to extract features and classify COPD severity with 85.89% accuracy. This technique provides an easy-to-use alternative to spirometry for COPD diagnosis and assessment.