Association between physical activity and symptoms in the daily lives of patients with COPD: a study using ecological momentary assessment

<bold>Background</bold> Previous research identified significant associations between physical activity (PA) and subjective symptoms in patients with COPD. However, the direction of these associations is unclear. <bold>Objective</bold> To investigate the direction of the association between PA and psychological symptoms, breathlessness and fatigue in patients with COPD using ecological momentary assessment (EMA). <bold>Methods</bold> Participants from the FAntasTIGUE study answered eight EMA questionnaires per day at random time points, for 5 consecutive days. Ten subjective feeling states were rated on a 7-point Likert scale: ‘I feel relaxed, short of breath, energetic, cheerful, insecure, irritated, satisfied, anxious, tired, and mentally fit’. Concurrently, PA was assessed as total step count at a 15- and 30-minute time window pre- and post-EMA, using the ActiGraph GT9X Link. Multilevel modeling examining the direction of the association were controlled for pre-EMA steps and the previous EMA score. Significant confounders and time of day were included as covariates. <bold>Results</bold> Thirty-four patients (66±7 years, FEV1% 52.1±19.7, 56% men) with valid data were included. Feeling more relaxed was associated with a higher step count 15 minutes post-EMA. A higher step count at 15 and 30 minutes pre-EMA was associated with feeling less relaxed, and more breathlessness and tiredness. Additionally, more steps taken 15 minutes pre-EMA was associated with feeling less satisfied (all p≤0.05). <bold>Conclusion</bold> Feeling relaxed suggests a bidirectional association with PA. Psychological symptoms, breathlessness and fatigue appear to be a consequence of performing PA instead of being the cause.