Sex differences in motor performance and anaerobic peak power of Japanese primary school children aged 11 to 12 years

The purpose of this study was to investigate sex differences in motor performance and anaerobic peak power in children. Furthermore, the relationship between power-associated variables and motor performance was also examined. Ninety-four Japanese primary school children aged 11 to 12 years volunteered. Grip strength, repeated lateral jumps, 50-m sprint, and standing broad jump were assessed following the guidelines published by the Japanese Ministry of Education and Science. Anaerobic peak power was assessed based on 6 sec sprint cycling with 4% of body mass as the braking load. The absolute peak power and peak power normalised by body mass were calculated as power-associated variables. The correlation analysis revealed that normalised peak power was moderately and strongly correlated with 50-m sprint time in both sexes, indicating the possibility that the sex difference in sprint performance could be derived from the discrepancy in anaerobic peak power. Sex differences were found in normalised peak power, lateral jumps, and 50-m sprint time. However, absolute peak power and standing broad jump did not differ significantly, and the results were not consistent with those of previous studies that examined participants in a different age range. The non-significant results in terms of absolute peak power and standing broad jump distance suggested the notion that sex differences in some variables fluctuate depending on the participants’ age. Therefore, future studies are required to investigate the sex differences in motor performance and anaerobic peak power in children of different age groups.