Copyright © American Speech-Language-Hearing Association From: Speech Breathing in Parkinson’s Disease J Speech Hear Res. 1993;36(2):294-310. doi:10.1044/jshr.3602.294 Legend: Mean values for rib cage and abdominal volume initiations and terminations during resting tidal breathing for the subjects with Parkinson’s disease (PD) and healthy control (HC) subjects. The diagonal solid line (slope = -1) represents the isovolume pathway at the resting expiratory level. The filled circle at the right end of the isovolume pathway represents end-expiratory level for resting tidal breathing. Date of download: 11/9/2017 Copyright © American Speech-Language-Hearing Association