摘要:tudy aim: While there is wide debate around specialization in one sport, there is a lack of information about fitness levels and motor competence of children participating in single or multiple sports.Material and methods: The study involved 358 fifth-grade children who participated in a set of health-related fitness and motor competence tests over two consecutive years. A subsample of children (n= 109) wore an accelerometer for seven consecutive days. The independent samples t-test and ANCOVA were used to compare differences between single and multi-sport participants in study variables and changes between baseline and follow-up.Results: Multi-sport participants performed better in shuttle run (baseline/follow-up;p= 0.001/p= 0.006), push-up (p= 0.006/p= 0.036), and five leap tests (p= 0.001/p= 0.009) in baseline than single sport participants among boys. Likewise, multi-sport participants showed significantly more improvement in the throwing and catching combination test between study years among boys F1,159= 3.570,p= 0.030. Among girls, no differences were found in any study variable between single and multi-sport participants.Conclusions: From the perspective of fitness and motor competence tests, there are no arguments for participating in just one sport at an early age. Instead, multi-sport participants performed better than single sport participants in the majority of test variables.