Purpose. This paper aims to examine how the knowledge of biomechanics, specifically of mechanics principles used in teaching aikido techniques, affects the precision of aikido movements execution. It also aims to answer the question whether secondary-school teaching of solid-state mechanics, using examples from aikido and other sports, improves the learning outcomes. Basic procedures. The experiment involved 60 second- and third-form secondary-school students, divided into two groups: F (n = 27) and E (n = 33). The research on the understanding of mechanics principles was based on the results of a written test. Group F (experimental group) had been taught the principles of rotation mechanics, using examples from aikido and other sports, as opposed to group E (control group). Surprise tests were applied to assess the understanding of mechanics rather than retrieving of definitions learned by heart. The experimental group took a written test to assess their understanding of aikido mechanics. Over the period of one month the students in this group had been taught four selected aikido techniques. Using a ten-point grading scale the precision of execution of aikido techniques was evaluated. Main findings. Student's t-test and regression analysis were used for statistical analysis. A statistically significant difference was found between the aikido-enhanced and the conventional ways of teaching solidstate mechanics: the experimental group attained much higher test results than the control group. There was a strong correlation between understanding aikido mechanics and the performance of aikido techniques. Conclusions. Understanding aikido mechanics improves the performance of aikido techniques. Teaching solid-state mechanics, using examples from aikido and other sports, is more effective than teaching physics in the conventional way.