Background: Daily physical activity is reduced in patients with chronic obstructive pulmonary disease (COPD) and a reduced level of physical activity has been shown to be an important predictor for the prognosis, such as increased risk of exacerbation and mortality. However, there has not yet been a useful biomarker of the physical activity. In our previous cross-sectional study, we showed that the level of one of the possible myokines, which is an anti-aging factor, growth differentiation factor 11 (GDF11), was decreased in the plasma from patients with COPD and correlated with the physical activity. To clarify this relation-ship, we conducted a longitudinal evaluation of such factors. Patients and Methods: Twenty-four COPD patients were enrolled and prospectively followed. We measured the levels of plasma GDF11 and systemic inflammatory markers with immunoblotting or ELISA, respectively. We also evaluated lung function and daily physical activity using a triaxial accelerometer and the incidence of exacerbation. Results: The change in the plasma level of GDF11, but not systemic inflammatory markers, was positively correlated with the change in the physical activity in an intensity-dependent manner (between the change in the number of steps and GDF11; r = 0.41, p = 0.047). In the multiple regression analysis, the relationship was confirmed (β = 0.93, p < 0.001). In addition, patients who maintained their plasma level of GDF11 showed a significantly lower incidence in exacerbations of COPD than those with decreased levels of GDF11 (p = 0.041). Conclusion: The longitudinal change in the plasma level of GDF11 was positively correlated with the change in the daily physical activity in COPD. GDF11 could be a useful humoral factor that reflects the physical activity in COPD.
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