Physical activity as a mediator in the relationship between health locus of control and health-related quality of life in multiple sclerosis patients with different disease duration

Background: The importance of undertaking physical activity for functioning of patients with multiple sclerosis (MS) has been repeatedly highlighted. However, the research on the role of physical activity in shaping the quality of life of patients with different disease duration is scarce. Objective: The aim of this study was to identify the mediating role of physical activity in the relationship between health locus of control (HLoC) and health-related quality of life in MS patients with varying disease duration. Methods: The study included 339 patients with MS from rehabilitation centers. The Multiple Sclerosis Impact Scale (MSIS-29) was used to measure health-related quality of life, physical activity was assessed by the Godin Leisure Time Exercise Questionnaire (GLTEQ) and the Health Locus of Control Questionnaire was used to measure HLoC. Results: Physical activity has been shown to be a mediator in the relationship between intrinsic HLoC and healthrelated quality of life particularly in patients with longer disease duration. Intrinsic HLoC was positively associated with engaging in physical activity, which in turn was positively associated with the physical component of quality of life in patients with longer (indirect effect: (3 = -0.077, p <0.05) and moderate ((3 = -0.040, p < 0.05) duration of illness. Conclusion: The results highlight the importance of psychological resources for undertaking quality-of-life-related physical activity by MS patients with long disease duration. Particularly important here is the internal HLoC, which promotes physical activity that increases the chance of a high quality of life.