Objectives. To describe postoperative self-reported physical activity (PA) level and assess the effects of 2 weeks of postoperative inspiratory muscle training (IMT) in patients at high risk for postoperative pulmonary complications following lung resection. Methods. This is a descriptive study reporting supplementary data from a randomized controlled trial that included 68 patients (mean age = 70 ± 8 years), randomized to an intervention group (IG; n = 34) or a control group (CG; n = 34). The IG underwent 2 weeks of postoperative IMT added to a standard postoperative physiotherapy given to both groups. The standard physiotherapy consisted of breathing exercises, coughing techniques, and early mobilization. We evaluated self-reported physical activity (Physical Activity Scale 2.1 questionnaire) and health status (EuroQol EQ-5D-5L questionnaire), assessed the day before surgery and 2 weeks postoperatively. Results. A significant percentage of the patients in the IG reported less sedentary activity 2 weeks postoperatively when compared with the CG (sedentary 6% vs 22%, low activity 56% vs 66%, moderate activity 38% vs 12%, respectively; P = .006). The mean difference in EQ-5D-5L between the IG and CG 2 weeks postoperatively was nonsignificant ( P = .80). The overall preoperative EQ-5D-5L index score for the study population was comparable to a reference population. Conclusion. Postoperative IMT seems to prevent a decline in PA level 2 weeks postoperatively in high-risk patients undergoing lung resection. More research is needed to confirm these findings.