Effects and Social Design Features of Physical Activity Interventions on Loneliness and Subjective Well-Being in Older Adults: A Systematic Review

Introduction: Physical activity is promoted in later life, yet its capacity to reduce loneliness or improve subjective well-being remains uncertain when social contact is incidental rather than intentionally designed. This review synthesised intervention effects and examined whether social-design features accompanied better outcomes. Method: Following PRISMA 2020, Web of Science Core Collection, PubMed and CENTRAL were searched for controlled studies published during 2022–2026. Eligible studies involved adults aged 60 years or older and reported loneliness, life satisfaction, subjective happiness, positive affect or negative affect. Twenty-one studies were included. Results: Findings for loneliness and life satisfaction were predominantly null or inconsistent. Favourable results for subjective happiness and negative affect were confined to a small number of studies and rarely assessed beyond the intervention period. No social-design theme showed a consistent advantage, while group or digital delivery without relational content did not reliably improve outcomes. Formal analyses of delivery mode, participant context, sex, gender or equity-related factors were uncommon. Conclusion: Evidence does not support a consistent psychosocial benefit of physical activity alone. Future interventions should separate physical and relational objectives, test social mechanisms directly and evaluate effects across diverse populations and settings.