Impact of perioperative physical exercise on postoperative pulmonary complications in patients undergoing cardiac surgery: a systematic review and meta-analysis

Background Postoperative pulmonary complications (PPCs) increase morbidity and hospital stay after cardiac surgery. Perioperative respiratory-focused exercise interventions, including inspiratory muscle training (IMT), incentive spirometry, and breathing exercises, may reduce PPCs, but the effects of these heterogeneous interventions in cardiac surgery patients remain uncertain. Methods A systematic review and meta-analysis were conducted using PRISMA guidelines and included 11 randomized controlled trials (RCTs) evaluating perioperative exercise or respiratory-focused interventions administered before and/or after cardiac surgery. The principal components of the interventions included IMT, incentive spirometry, deep breathing exercises, and surgical respiratory re-education exercises. The analysis was conducted using RevMan 5.4, with Rayyan used to assist in the screening and selection of studies. Results Perioperative exercise or respiratory-focused interventions significantly reduced selected pulmonary outcomes, including PPC grade ≥2 (RR = 0.47, 95% CI: 0.33–0.67), pneumonia (RR = 0.56, 95% CI: 0.38–0.83), and atelectasis (RR = 0.39, 95% CI: 0.24–0.64). No statistically significant effects were observed for pleural effusion, respiratory failure, hypoxemia episodes, or re-intubation. Mechanical ventilation duration (SMD = −0.70, 95% CI: −1.04 to −0.37), ICU length of stay (SMD = −1.09, 95% CI: −1.81 to −0.36; I 2 = 85%), and hospital length of stay (SMD = −0.70, 95% CI: −0.97 to −0.44; I 2 = 40%) showed reductions. MIP (SMD = 0.89, 95% CI: −0.08 to 1.86; I 2 = 94%) and 6MWD (SMD = 0.13, 95% CI: −0.31 to 0.57; I 2 = 34%) did not demonstrate statistically significant improvement when analyzed as separate outcomes. Certainty of evidence ranged from moderate to very low. Conclusions Perioperative respiratory-focused exercise interventions may reduce selected postoperative pulmonary complications and may improve some short-term recovery outcomes in patients undergoing cardiac surgery. However, substantial variation in intervention type, timing, and duration, together with risk of bias and heterogeneity for some outcomes, resulted in moderate to very low certainty of evidence and limits the generalizability of the findings. The available evidence remains insufficient to determine an optimal exercise protocol or to establish consistent improvements in respiratory muscle strength or functional exercise capacity. Systematic Review Registration https://www.crd.york.ac.uk/PROSPERO/view/CRD420261294365 , identifier CRD420261294365.