Physical Activity as a Tool for Social Inclusion in Multiple Sclerosis: A Systematic Review of Qualitative, Quantitative, and Mixed-Methods Evidence

<b>Background</b>: People with multiple sclerosis (PwMS) face a wide range of social barriers, including stigma, limited support, and inaccessible environments, that restrict participation in physical activity (PA). Although PA is known to improve physical and psychological outcomes, its role in reducing social barriers has not been clearly synthesized. <b>Methods</b>: Following PRISMA 2020 guidelines, we conducted a systematic search of PubMed, Scopus, and Web of Science (January 1997-October 2025). Qualitative, quantitative, and mixed-methods studies examining how PA relates to social barriers, facilitators, or social outcomes for PwMS were included. Data were synthesized using a thematic analysis approach due to heterogeneity in study designs and outcomes. Risk of bias was assessed using JBI, NIH, RoB 2.0, and MMAT tools. <b>Results</b>: Twenty-nine studies met the inclusion criteria. The thematic synthesis identified three overarching mechanisms through which PA contributes to reducing social barriers: (1) peer support and shared experience, whereby group-based PA reduced isolation and normalized fluctuating symptoms; (2) guidance from knowledgeable professionals, which fostered trust, confidence, and perceived safety; and (3) changes in social identity, with participants shifting from a "sick role" toward identities such as "exerciser" or "athlete." These mechanisms were supported by high-quality qualitative studies and by quantitative evidence showing small-to-moderate effect sizes for improvements in self-efficacy, social participation, and perceived social support. <b>Conclusions</b>: PA functions as a socially transformative practice for PwMS when delivered in group-based, supervised, and accessible formats. Programs designed to intentionally cultivate peer connection, professional support, and identity-building processes may be especially effective in overcoming social barriers and promoting social inclusion.