Muscle carnosine concentration in patients with COPD is not significantly different from that in healthy age- and sex-matched controls, even in the presence of reduced muscle endurance and increased fast-twitch fiber proportion, indicating that carnosine depletion is not a universal feature of COPD but is specifically linked to disease severity.

In people with severe COPD, muscle tissue experiences high levels of harmful chemicals called reactive aldehydes. Carnosine in the muscle binds to these chemicals to neutralize them, but in doing so, carnosine gets used up and cannot be replaced fast enough. This causes carnosine levels to drop only in those with the most severe disease, even when muscle fiber type and overall muscle health suggest it should stay normal.