BACKGROUND: Persistent disability in chronic stroke survivors is often attributed to arm or leg weakness; however, respiratory muscle weakness also impedes poststroke rehabilitation, reduces quality of life, and increases the risk of health complications. Respiratory complications are common after stroke and place patients at risk for both prolonged functional disability and mortality. In addition, stroke survivors face ongoing cardiovascular disease that places them at risk for recurrent stroke. OBJECTIVE: The study aims to compare the effects of 2 respiratory training programs, paired with individualized flexibility, strengthening, and cardiovascular exercise programs, on physiologic, activity, and societal participation outcomes in chronic stroke survivors. METHODS: This study will be a randomized controlled trial. Participants are 80 community-dwelling adults with chronic stroke. In conjunction with a 24-session (3 times/week for 8 weeks), American Heart Association-informed, whole-body exercise program, participants will be randomized to receive either respiratory strength training or respiratory relaxation training. Study intervention will be directed by a physical therapist and take place in a community fitness center. Outcome assessments will occur in a clinical research center. The primary outcome measure is maximal respiratory pressure. Secondary outcome measures include airway clearance, walking endurance, spatial-temporal gait characteristics, community walking, functional strength and fatigue, depression, and societal participation measures. Longer-term societal participation is a complex domain that may be influenced by other factors beyond physical function. Participants' health status will be monitored for 1 year following the intervention for falls, respiratory illness, and hospitalizations. Additional subanalyses will evaluate the effect of smoke exposure on short- and long-term outcomes. Outcome assessors are blinded to group assignments. Respiratory relaxation training is an active comparator, but no pure control group is included. RESULTS: This study was funded in March 2020 with enrollment commencing in November 2020. Completion of enrollment is projected for May 2025 with a study projected end date of April 2026. Published results are anticipated in Fall 2026. CONCLUSIONS: Results from this study will improve our understanding of the additive benefits of respiratory exercises on short- and long-term physiologic, functional, and societal gains for these individuals. These data will be instructive to meet a current unmet rehabilitative need to promote patient-centered care and contribute to decreasing morbidity and mortality in chronic stroke survivors. TRIAL REGISTRATION: ClinicalTrials.gov: NCT05819333; https://clinicaltrials.gov/study/NCT05819333. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): DERR1-10.2196/59749.