The research objective is to determine the age-related peculiarities of development of motor abilities in 12-14-year-old boys. To achieve the tasks set, the research used the following methods: theoretical analysis and collation of scientific and methodological literature, pedagogical testing, methods of mathematical statistics. To determine the age-related changes in the motor readiness, the 12-14-year-old boys took some commonly known tests, and the results obtained underwent analysis by the Hotelling criterion. The study involved 12 boys aged 12, 12 boys aged 13, and 12 boys aged 14. Conclusions. The boys within the age range of 12-14 manifested an increase in their speed force and speed. With age, the 12-14-year-old boys do show positive dynamics in the tests “Bending and unbending of arms in the lying support”, “1,500 m running”. The 12-14-year-old boys demonstrated a clear structure of motor readiness, which tends to change with age. If endurance and relative strength are the priorities in development at the age of 12, it is agility and speed force that come to the forefront at the age of 14.