Trends in muscular fitness performance among 9-12-year-olds: implications for monitoring and test selection

Background and Study Aim: Long-term trends in muscular fitness show a gradual decline, which has become even more intense due to the Covid-19 pandemic. Declines in muscular fitness are associated with deteriorated health and well-being parameters. It is crucial to monitor this decline and appropriate tests need to be selected and interpreted correctly. The aim of this research was to apply muscle fitness tests and compare the development of performance between 9 and 12-year-olds and, at the same time, to compare performance differences between boys and girls. Material and Methods: 225 girls and 259 boys aged 9 to 12 years (11.1 ± 0.9) took part in the studies. Seven tests were selected to assess muscular fitness: bent-arm hang (BAH), push-ups, sit-ups, standing broad jump (SBJ), medicine ball throw (MBT), handgrip dynamometry (handgrip), and pulling back-leg dynamometry (back-leg). Results: The results showed that the development curves of muscle tests are incomparable. A linear increase was recorded for the MBT test. The handgrip, back-leg, and MBT tests have similar development although they do not test the same type of force. A very different trend (stagnation, decline) was found for the BAH and push-up tests. Girls and boys showed a comparable trend in all tests, however, boys always had higher absolute performances. Conclusions: Our data are intended to contribute to the expert discussion on the choice of muscular fitness tests. Based on these results, the selection of multiple tests may be recommended for optimal assessment of muscular fitness. In future research, it would be advisable to follow up by testing a larger cohort.