The purpose of this paper isto preparing different training loads to develop speed endurance, adapt heart rate and achieving 400-meter hurdles under 20 years, and recognizing the effect of different training loads on developing speed endurance, adapting heart rate, and achieving 400-meter hurdles under 20 years.The researchers used the experimental method with an experimental design with a pre and post-test for the two equal groups (experimental and control) for its suitability to the nature of the research.The research community was determined for the players of the Babylon Governorate clubs (Al-Hilla Club 2 players), (Al-Kifl Club 2 players),(Al-Mahaweel Club 2 players), Al-Masharou Sports Club 2 players), (Al-Musayyib Sports Club 2 players) in the 2022 sports season, and their number is ( 10 players), as the research sample was chosen in a comprehensive inventory method, and the sample was divided into two groups, the experimental group and the control group,with (5 players) for each group

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