A hypothesized benefit of social participation is that it encourages people to be more physically active. However, limited evidence exists on the association between social participation over the life-course and physical activity in midlife. We sought to apply a life-course framework to examine the association of social participation and device measured physical activity in midlife in the UK. We used the 1970 British Birth Cohort Study (BCS70), which includes all people born in Britain during a single week in 1970. Social participation was assessed at ages 16, 30, 34 and 42. Physical activity was measured by accelerometery at age 46, as mean daily step count and time spent in moderate to vigorous physical activity (MVPA). The associations of social participation and physical activity were tested using two different life-course models: the sensitive period model and the accumulation model. Individuals with medium and high participation compared to no social participation over their life-course had higher mean daily step count and MVPA in midlife, supporting the accumulation model. In the sensitive period model, only those that actively participated at age 42 had higher mean daily steps and MVPA compared to those who did not participate. Our study provides empirical evidence on the importance of sustaining social participation at all ages over the life-course rather than at a particular timepoint of someone’s life. If our findings reflect causal effects, interventions to promote social participation throughout the life-course could be an avenue to promote physical activity in middle life.

社会参与的一个假设好处是它鼓励人们更加活跃。然而，关于生命历程中的社会参与与中年体力活动之间的关联的证据有限。我们试图应用生命历程框架来研究英国中年社会参与与设备测量的身体活动之间的关系。我们使用了 1970 年英国出生队列研究 (BCS70)，其中包括 1970 年一周内在英国出生的所有人。在 16、30、34 和 42 岁时评估了社会参与度。在 46 岁时通过加速度计测量了体力活动，平均每日步数和中度至剧烈体力活动所花费的时间 (MVPA)。使用两种不同的生命历程模型测试了社会参与和体育活动的关联：敏感期模型和积累模型。与一生中没有社会参与的个体相比，中度和高度参与的个体在中年时平均每日步数和 MVPA 更高，支持累积模型。在敏感期模型中，只有那些在 42 岁时积极参与的人与未参与的人相比，平均每日步数和 MVPA 更高。我们的研究提供了经验证据，证明在生命历程中的各个年龄段而不是在生命的特定时间点维持社会参与的重要性。如果我们的研究结果反映了因果效应，那么促进整个生命过程中社会参与的干预措施可能成为促进中年身体活动的途径。