For school-age children to live with health and vitality in modern society, they need suitable physical strength and athletic ability, and measurements of physical strength and athletic ability that assesses those abilities are often considered essential. To address the problem of declining physical strength in recent years, City O has adopted an action plan. This action plan was established from a continuous 7-year survey of physique, physical strength, and athletic ability in fifth grade elementary school students and second year junior high school students. This study, to assess the effectiveness of City O's action plan, examined whether the trends in physical strength and athletic ability over those 7 years were rising or falling by analyzing the changes over time. The system adopted in this action plan is to measure the same items as in the physical strength and athletic ability survey conducted by the Ministry of Education, Culture, Sports, Science and Technology. From the results it is thought that an increase in exercise time was one factor in increased physical strength in City O. Behind this increase in exercise time was an increase in the percentage of children who belonged to a school team or sports club, and an increase in the percentage who responded that "Physical education class is fun." Above all was that action plans were included in the annual programs of all elementary and junior high schools in City O. and intentionally and systematically implemented. Therefore, in the system for increased physical strength and athletic ability based on the action plan of City O, exercise and physical activity time is ensured with participation in school teams or sports clubs. Furthermore, it is recognized that increasing the percentage of students who say that "physical education class is fun" was effective in raising the total score for physical strength and athletic ability over time. Particularly in second year junior high school girls, it would seem that the optimal valid physical strength of City O junior high school students could be advocated as a model for improving physical strength and athletic ability.