The research aims to study the effect of 5-10-15 training on the development of anaerobic speed reserve, some physical and physiological variables and the digital level of the 800-meter race for juniors under 18 years old. The researchers used the experimental method by following the experimental design for the two groups, one experimental and the other control using the pre- and post-measurements for both groups. The research sample was chosen intentionally and included (10) 800-meter racers under 18 years old from Kafr Saqr Club in Sharkia Governorate and registered with the Egyptian Athletics Federation for the 2020/2021 season. The researchers also used (4) racers from the same research community and outside The basic research sample for conducting the exploratory study and scientific transactions The researchers processed the data statistically using the following statistical analysis methods: arithmetic mean - standard deviation - median - skewness coefficient - simple correlation coefficient - Mann-Whitney test (i) - Wilcoxon test (y) - improvement rates (%) The most important results were that the 5-10-15 training has a positive effect on the development of anaerobic speed reserve, and some physical variables (acceleration, transitional speed, speed endurance and muscular capacity) and physiological variables (maximum oxygen consumption, maximum aerobic speed, maximum and average anaerobic capacity and fatigue index) and the digital level of the 800-meter race. There were also statistically significant differences between the experimental and control groups in the post-measurement of anaerobic speed reserve, physical variables (acceleration, transitional speed, speed endurance and muscular capacity) and physiological variables (maximum oxygen consumption, maximum aerobic speed, maximum and average anaerobic capacity and fatigue index) and the digital level of the race 800 meters were run for the experimental group and there were improvement rates for the post-test compared to the pre-test for the research sample members in the tests under study, as they ranged between (3.8%: 25.96%) in the experimental group and ranged between (2.31%: 18.99%) in the control group.