BackgroundBeyond the acute phase, a considerable proportion of patients recovering from the coronavirus disease 2019 (COVID-19) experience long-term sequelae that profoundly impact their quality of life, particularly their physical fitness. This study aims to assess the effect of home-based breathing and chest mobility exercise on the cardiorespiratory functional capacity of long COVID with cardiovascular comorbidity.MethodsIn this randomized, controlled, single-blind clinical trial, 46 long COVID with cardiovascular comorbidities were randomly assigned to either intervention or control group. The intervention group (n = 23) received additional home-based breathing and chest mobility exercise 3x/week for 12 weeks supervised by attending physicians, whereas the control group only received a home-based cardiac rehabilitation program. Baseline and post-intervention assessments consisted of laboratory (D-Dimer and CRP levels) and functional capacity, assessed through 6-minute walking test (6-MWT), exercise stress test’s metabolic equivalents (METS), and predicted peak oxygen consumption (VO2 peak), peak expiratory flow rate (PEFR), peak cough flow (PCF), chest expansion, and EuroQoL’s quality of life. Intention to treat analysis was performed.ResultsAt the 12th week, intervention subjects had significantly greater functional capacity with higher mean PEFR (p = .031) and PCF (p = .016). Similarly, 6-MWT was higher in the group receiving home-based breathing and chest mobility training (p = .032). The bottom part of the chest circumference was statistically different between the two groups (p = .01). METS and predicted VO2 peak were also higher in the intervention group. However, laboratory parameters and quality of life did not differ markedly (p > .05).ConclusionsHome-based respiratory and chest mobility exercise could be an adjunct to cardiac rehabilitation in long COVID with cardiovascular comorbidities for improving cardiorespiratory functional capacity.Trial registrationThe study protocol was registered at http://ClinicalTrial.gov.id NCT05077943 (14/10/2021).