The research aims to compare the effect of training with short or long repetitions on the development of some physical and physiological variables (maximum aerobic speed, maximum oxygen consumption and anaerobic capacities) and the numerical level of the 1500m race. Statistical manipulations: - arithmetic mean - standard deviation - median - skew coefficient - Simple correlation coefficient - Mann-Whitney test (j) - Test (t) - percentage of improvement (%) - Cohen's test (d) to measure the effect size (low effect ≥ 0.2, medium effect ≥ 0.5, high effect ≥ 0.8). The most important conclusions were: 1- Training with short-term repetitions positively affects the development of some physical and physiological variables (maximum oxygen consumption, maximum aerobic speed, time to fatigue, anaerobic abilities) and the digital level of the 1500m race. 2- Training with long-term repetitions positively affects the development of some physical and physiological variables (maximum oxygen consumption, maximum aerobic speed, time to fatigue, anaerobic abilities) and the digital level of the 1500m race. The most important recommendations were: 1- The use of training with short-term or long-term repetitions interchangeably to reduce the monotony of training and in developing physical and physiological variables and running performance in track and field competitions. 2- A comparison between the effects of training with short and long repetitions and other types of high intensity interval training on developing aerobic and anaerobic abilities and the digital level of medium and long sprints. 3- Studying the functional and biochemical responses to each of the training with short or long duration repetitions and comparing them between middle and long distance runners of both sexes and different age groups.