Pulmonary rehabilitation (PR) improves functional capacity in individuals with Chronic Obstructive Pulmonary Disease (COPD); however, these effects diminish over time, and these individuals exhibit a vicious cycle of sedentary behavior, leading to functional losses. However, there are still gaps in the literature regarding whether this behavior influences functional capacity, physical activity levels post-PR, and the maintenance of long-term benefits.

To verify whether pre-PR sedentary time can explain functional capacity and physical activity levels post-rehabilitation and over six months.

This is a longitudinal study conducted on individuals with COPD who completed an eight-week PR program based on functional tests. The study was approved by the institution's Ethics Committee. Participants were assessed at three time points: pre-PR, post-PR and six months after PR. The assessments included functional capacity (six-minute walk test - 6MWT and six-minute step test- 6MST). To measure sedentary behavior and physical activity levels, an accelerometer was worn on the right thigh for seven consecutive days. The accelerometer data were processed using ActiPASS software, and repeated measures ANOVA, Pearson Correlation and simple linear regression analysis were conducted using SPSS. The significance level was set at p = 0.05.

A total of 26 individuals with COPD were evaluated, with a mean age of 67 ± 7 years, 15 (58%) males, FEV1 of 51 ± 14%, and a BMI of 25±5 Kg/m². There was a significant improvement in functional capacity from pre- to post-PR with no differences after six months. Regarding physical activity levels, no significant differences were found across the three time points. A correlation was observed between pre-PR sedentary time and 6MWT (r = -0.506, p = 0.008), 6MST (r = -0.532, p = 0.005), post-PR physical activity level (r = -0.616, p = 0.001) and six-month post-PR physical activity level (r = -0.760, p < 0.001). Regression analyses showed that the pre-PR sedentary time explained 22.5% of the variance in functional capacity for the 6MWT (adjusted R² = 0.225, p = 0.008), 25.4% for the 6MST (adjusted R² = 0.254, p = 0.005), 35.3% for the post-PR physical activity level (adjusted R² = 0.353, p = 0.001), and 55.6% for six month post-PR physical activity level (adjusted R² = 0.556, p < 0.001).

Pre-PR sedentary time explained the variance in functional capacity and physical activity levels post-PR, as well as long-term physical activity levels. This reinforces the need to encourage more sedentary individuals to break this behavior during and after PR to maintain functional gains.

The findings of this study highlight the importance of Behavior change strategies targeting more sedentary individuals to enhance PR responses and maintain its long-term benefits.