Israa Kamil Hasan and Asmaa Hameed Gambash 2023. The effect of exercises in both high and repetitive interval training methods to develop speed endurance, strength endurance, and the achievement of 400 meters’ hurdles under (18) years old. Modern Sport. 22, 1 (Mar. 2023), 0078. DOI:https://doi.org/10.54702/ms.2023.22.1.0078.