Objectives: Regarding children's and adolescents' development of physical fitness (PF), information about whether there are different performance classes in PF would potentially be helpful. If such classes also differ in related health parameters, this might indicate 'at-risk' groups requiring different support measures.
Methods: Factor mixture modeling was used to investigate whether participants of the German "Motorik"-Module (2003-2006) aged 6-17 years (N = 4,529) differ in their PF as described by endurance, strength, coordination, and flexibility.
Results: Four different classes of PF emerged after controlling for age and gender. Participants in classes 1 and 2 either performed well in all coordination or in all strength tests. Participants in class 3 and class 4 performed poorly in all coordination and in the push up (strength) tasks. Only participants in class 4 revealed significantly higher BMI values and less physical activity suggesting they are, in fact, an 'at-risk' group.
Conclusions: Different support measures are needed to enable adequate development. There might be a risk group demonstrating comparably low coordination that cannot be spotted by looking at BMI or activity level.