Shakir, H., Khazal Jabbar, A. ., & Louis William, W. . (2026). Effect of interval training with two methods gradual and intermittent in development of some special physical variables and achievement of running 400 m for juniors. مجلة دراسات وبحوث التربية الرياضية, 36(4). https://doi.org/10.55998/jsrse.v36i4.1450