Individual factors associated with physical activity adherence in schizophrenia: an exploratory secondary analysis of two randomized controlled trials

IntroductionPhysical activity is an effective adjunctive therapy in schizophrenia, improving psychiatric symptoms and reducing the mortality rate. However, individuals with schizophrenia engage in lower levels of physical activity compared to the general population, and adherence to structured exercise programs remains low. The factors underlying sustained engagement are still not well understood. This study aimed to investigate factors associated with adherence to an exercise intervention in individuals with schizophrenia and to explore whether personality characteristics are related to physical fitness outcomes.MethodsThe present investigation was a secondary analysis of data from two randomized controlled trials conducted at the LMU Munich, which included N = 100 participants. Participants completed a three-month, professionally supervised exercise intervention, consisting of either aerobic endurance training or flexibility, strength, and balance training. Assessments at screening and baseline included sociodemographic characteristics, lactate threshold testing, physical fitness measures, personality and motivational questionnaires, and clinical and functional ratings. Multiple regression analyses were used to examine adherence as the primary outcome and physical fitness as a secondary outcome. The predictor variables included motivation, personality traits, symptom severity, previous exercise experience and emotional support, baseline fitness level, affective forecasting, and satisfaction with exercise training.ResultsThe results revealed no significant associations between any of the investigated variables and adherence after correction for multiple testing (all p > 0.05). Similarly, physical fitness was not significantly associated with personality- related variables in this study.DiscussionOverall, the examined variables explained only a limited proportion of the variance in the two outcomes. These findings suggest that the investigated variables do not fully explain adherence or physical fitness and that both outcomes may be influenced by additional contextual determinants of exercise behavior in schizophrenia.