High-altitude hypoxia alters the developmental trajectory of working memory in Tibetan children.

Happiness has become increasingly important outcomes in research on quality of life and public health. A large body of scholarship has shown that physical activity is positively associated with mental health, happiness, and broader social outcomes (). In the Chinese context, recent evidence likewise suggests that physical activity is positively related to happiness (), while newer studies indicate that leisure-time physical activity may be especially beneficial for happiness and mood (). Yet much of this literature still approaches physical activity primarily as an individual behavior, emphasizing what exercise does for the body and the mind, rather than asking how different social forms of participation may shape these benefits. This question matters because, in contemporary society, sport is increasingly practiced not only as a private or spontaneous activity but also as an organized social practice. Sports clubs are one of the clearest manifestations of this transformation (). They do not merely provide opportunities for exercise; they also structure participation through repeated interaction, group routines, and shared identities (). For that reason, the impact of sports clubs on happiness may not be reducible to “doing more exercise.” Rather, it may depend on whether club membership is translated into active participation, regular engagement, and embeddedness in a stable social setting. Recent studies support this possibility. Physical activity in social settings appears to generate happiness benefits partly because of processes such as social identification, not simply because people are physically active more often (). Likewise, participation in sports clubs has been associated with stronger health behaviors and better perceived health outcomes, suggesting that clubs matter as organized settings that sustain activity and social involvement over time (). However, an important question remains unresolved in the existing literature. Previous studies have shown that physical activity and organized sport settings are associated with mental health, happiness, and social outcomes (, , ). Yet less is known about whether the happiness advantage of sports clubs is linked merely to formal membership or to actual participation in club-based activities. This issue is important because sports clubs are not only organizational settings but also contexts in which individuals may engage more fully in physical activity. This study therefore examines whether sports club participation (SCP) is associated with happiness and whether this association depends on actual participation rather than formal membership alone. Rather than treating club participation as a simple binary condition, the analysis distinguishes among non-members, inactive members, and active members, thereby separating nominal affiliation from substantive engagement. The central question is whether happiness is associated merely with belonging to a sports club, or with actively participating in it and engaging more fully in physical activity. By addressing this question, the study contributes to the literature in two ways. First, it shifts attention from broadly defined physical activity to organized SCP, highlighting the importance of distinguishing formal membership from active participation within sport organizations. Second, it examines whether the association between SCP and happiness is connected to behavioral engagement in physical activity, thereby moving beyond a simple membership-based explanation and providing a more nuanced account of how organized sport participation is associated with happiness.