Inspiratory muscle strength and skeletal muscle mass are associated with postoperative functional exercise capacity after lung cancer surgery: A retrospective cohort study

Although surgical resection is the cornerstone of curative treatment for early-stage lung cancer, patients often experience postoperative declines in physical fitness and skeletal muscle mass, resulting in reduced exercise capacity, which is associated with prognosis. This study aimed to identify clinical factors associated with postoperative functional exercise capacity, as measured by the incremental shuttle walk test, in patients undergoing lung cancer surgery. This retrospective study included 62 subjects (mean age, 67 ± 8.7 years; 24 women and 38 men) who underwent lung cancer surgery and completed a postoperative assessment at 3 months. Functional exercise capacity was assessed using the incremental shuttle walking distance (ISWD) as the primary outcome. Correlation and regression analyses were conducted to examine the associations between ISWD and concurrent measures of forced expiratory volume in 1 second, forced vital capacity, maximal inspiratory pressure (MIP), maximal expiratory pressure, and skeletal muscle index (SMI). At 3 months postoperatively, ISWD was negatively correlated with age (r = -0.354, P = .005) and positively correlated with SMI (r = 0.253, P = .048) and predicted MIP (%; r = 0.293, P = .02), whereas other pulmonary function parameters were not significantly associated with ISWD. In regression models adjusted for 1-month ISWD, age, and sex, both predicted MIP (%; β = 0.290, P = .03; ΔR2 = 0.079) and SMI (β = 0.340, P = .03; ΔR2 = 0.075) were independently associated with 3-month ISWD. Subjects with low SMI demonstrated significantly lower 3-month ISWD than those with normal SMI (P = .02). Skeletal muscle mass and inspiratory muscle strength were associated with functional exercise capacity assessed using the incremental shuttle walk test at 3 months after lung cancer surgery. These findings suggest that assessment of muscle-related factors may improve the evaluation of postoperative functional recovery and help identify potential targets for rehabilitation.