The Effects of Yoga Breathing Before Motor Speech Practice in Acquired Apraxia of Speech: An n-of-1 Trial

Abstract A previous study discovered that two speakers with moderate apraxia of speech increased their sequential motion rates after unilateral forced-nostril breathing (UFNB) practiced as an adjunct to speech-language therapy in an AB repeated-measures design. The current study sought to: (1) delineate possible UFNB plus practice effects from practice effects alone in motor speech skills; (2) examine the relationships between UFNB integrity, participant-reported stress levels, and motor speech performance; and (3) sample a participant-led UFNB training schedule to contribute to the literature's growing understanding of UFNB dosage. A single-subject (n-of-1 trial), ABAB reversal design was used across four motor speech behaviors. A 60-year-old female with chronic, severe apraxia of speech participated. The researchers developed a breathing app to assess UFNB practice integrity and administer the Simple Aphasia Stress Scale after each UFNB session. The participant improved from overall severe to moderate apraxia of speech on the Apraxia Battery for Adults. Visual inspection of graphs confirmed robust motor speech practice effects for all variables. Articulatory-kinematic variables demonstrated sensitivity to the UFNB-plus-practice condition and correlated to stress scale scores but not UFNB integrity scores. The participant achieved 20-minute UFNB sessions 4 times per week. Removal of UFNB during A2 (UFNB withdrawal) and after a 10-day break during B2 (UFNB full dosage) revealed UFNB practice effects on stress scale scores. UFNB with motor speech practice may benefit articulatory-kinematic skills compared to motor speech practice alone. Regular, cumulative UFNB practice appeared to lower self-perceived stress levels. These findings, along with prior work, provide a foundation to further explore yoga breathing and its use with speakers who have apraxia of speech.