BACKGROUND: Adequate physical activity is essential to maintain and improve physical health, including in adolescents and young adults. A significant part of physical activity is sports activity. However, few longitudinal studies cover the transition from adolescence to early adulthood. Therefore, the aim is to assess how the maintenance or a change in sports activity during this transition relates to physical fitness, BMI, and recurrent pain. METHODS: Data of 947 adolescents aged 11 - 17 years (53 % girls) from the Momo baseline (2003 - 2006) that were followed up at MoMo Wave 1 (2009 - 2012) were used. Sports activity was categorized (>
240 min/wk sports activity vs. RESULTS: The analysis revealed significant differences between the activity groups at the follow-up for CRF (F(3, 502) = 13.65, p <
.001), push-ups (F(3, 599) = 10.45, p <
.001), and standing long jump (F(3, 601) = 12.03, p <
.001). There were no significant differences in BMI between the groups (F(3, 610) = 0.08, p = .970). The odds for the low active group were two times higher to report recurrent headaches at the second measure compared to the consistently active ones. CONCLUSION: Participating in sports regularly from adolescence to early adulthood is associated with the strongest health benefits. Nevertheless, those who were less active initially but increased their sports activity had similar health outcomes, highlighting the importance of sports activity as part of a healthy lifestyle in young adulthood.