Relationships between physical activity and loneliness: A systematic review of intervention studies

Loneliness and physical inactivity are serious public health issues that often co-occur. However, they are often treated separately. Our systematic review aimed to identify components of interventions that most effectively improve physical inactivity and/or loneliness and whether/how these two variables are related. Specifically, we tested the following questions: 1) whether interventions focused on physical inactivity alleviate loneliness; 2) whether interventions focused on loneliness increase physical activity; 3) whether interventions that target broader levels of physical and mental well-being improve both loneliness and physical activity. We further examined 4) common intervention components that influenced loneliness and/or physical activity, with a particular focus on social components of each intervention. We searched for peer-reviewed journal articles published before May 22nd, 2022 in PubMed Plus, Scopus, Web of Science, ScienceDirect, EBSCO, and Embase. Both quantitative and qualitative studies that investigated the effects of interventions on physical activity and/or loneliness were included for review. Risk of bias was assessed for each study. We identified 34 papers, including 27 studies examining the effects of physical activity interventions, one study explicitly targeting loneliness, and six studies targeting broader subjective well-being. Studies showed mixed results and a high heterogeneity in intervention design and sample characteristics. Overall, we found group exercise, individualized consultation and education on physical activity, and social support-building during physical activity (vs. other social activities) as promising intervention components that were frequently associated with improvements in physical activity and loneliness. This review highlights that interventions targeting physical activity can also alleviate loneliness. Improved social experiences from such interventions may explain this hidden benefit. Limited data were available to conclusively answer whether physical activity and loneliness bi-directionally influence each other. More research is needed to systematically test the impact of different social components built into physical activity interventions on loneliness.