The modified Medical Research Council scale misclassifies exertional breathlessness among people referred for exercise testing.

Among people referred for clinical exercise testing, the mMRC dyspnoea scale misclassified exertional breathlessness and exercise capacity assessed using cycle IET, with substantial underdetection. A mMRC dyspnoea rating of 0-1 does not preclude the presence of abnormally high exertional breathlessness or abnormally low exercise capacity.