The indirect effects of basic psychological needs on the relationship between physical activity and mental health in adults with disabilities: a cross-sectional study

Introduction
Poor mental health is a common secondary health condition for adults with disabilities. The mental health benefits of moderate-to-vigorous intensity physical activity (MVPA) are well-documented. Few studies have empirically tested the relationship between MVPA and mental health among persons with disabilities. Additionally, theoretically informed factors that may mediate the relationship are not commonly tested among persons with disabilities. The primary aim of this study was to examine the cross-sectional relationship between MVPA and mental health in adults with disabilities. A secondary aim was to explore the indirect effects of the three psychological needs (autonomy, competence, relatedness) on the MVPA-mental health relationship.

Material and methods
Participants (n = 100; Mage = 36.61 +/- 11.51, 18-61 years; 54% women; 84% physical disability) completed an online questionnaire to assess MVPA, mental health, autonomy, competence, and relatedness. The associations between MVPA, psychological needs, and mental health were explored descriptively and in a multiple mediation regression model.

Results
The bivariate association between MVPA and mental health was significant (rs = .34, p = .01), as were the associations between the three psychological needs and MVPA (rs = .24-.43) and mental health (rs = .61-.82). The indirect effect of MVPA and mental health was significant through autonomy (β=.05, 95% CI = .00-.12), competence (β = .16, 95% CI = .08-.25) and relatedness (β = .08, 95% CI = .02-.17).

Conclusions
The results of this study add to limited research documenting the MVPA and mental health relationship in adults with disabilities through highlighting the potential benefits of autonomy, competence, and relatedness. Future prospective research is needed to investigate the mediating effects of autonomy, competence and relatedness on the MVPA and mental health relationship in adults with disabilities.