Towards a better understanding of physical activity in people with COPD: predicting physical activity after pulmonary rehabilitation using an integrative competence model.

The integrative Physical Activity-related Health Competence (PAHCO) model specifies competences (movement competence, control competence, and self-regulation competence) that enable people to lead a physically active lifestyle. This longitudinal study analyses the predictive quality of a multidimensional PAHCO assessment for levels of physical activity (PA) and their relevance for quality of life in COPD patients after pulmonary rehabilitation. At the end of an inpatient pulmonary rehabilitation (T2), 350 COPD patients participating in the Stay Active after Rehabilitation (STAR) study underwent assessments, including a six-factor measurement of PAHCO. PA (triaxial accelerometry) and quality of life (Saint George's Respiratory Questionnaire) were recorded 6 weeks (T3) and 6 months (T4) after rehabilitation. Structural equation modelling (SEM) was used to regress the PAHCO assessment on PA, which should, in turn, influence quality of life. In univariable analysis, five and six factors of the PAHCO model were related to PA and quality of life, respectively. Multivariate modelling showed that the predictive analyses for the PA level were dominated by the 6-minute walking test representing movement competence (0.562 ≤ |β| ≤ 0.599). Affect regulation as an indicator of control competence co-predicted quality of life at T3 and levels of PA at T4. The PA level was, in turn, significantly associated with patients' quality of life (0.306 ≤ |β| ≤ 0.388). The integrative PAHCO model may be used as a theoretical framework for predicting PA in COPD patients following pulmonary rehabilitation. The results improve our understanding of PA behaviour in COPD patients and bear implications for person-oriented PA promotion.