Military personnel must assume demanding physical activities during both tactical and physical training in military installations or theaters of operations. In military operations, high levels of aerobic capacity and muscular strength are required, that is why adequate fitness (aerobic endurance, muscular endurance, strength, flexibility, body composition) is an important factor in the performance and survival. PURPOSE: To determine the fitness of the military personnel in training of the different schools of the Colombian Army. METHODOLOGY: Cross-sectional study with an analytical component, where morphological and physiological variables were measured in 120 senior Military students in the three military training schools (ESMIC-Officers, EMSUB-NCOs and ESPRO-soldiers). The body composition was evaluated by electrical bioimpedance after checking the pre-test protocol conditions. The explosive strength of the upper and lower limbs was assessed in a jump platform, with the Push-Up and Squat Jump tests without load. The flexibility was assessed by the "Sit and Reach" test, the maximum consumption of VO2 with the "Léger" test and the prehensile force was evaluated by dynamometry. The comparisons were made using one-way analysis of variances (ANOVA) and post hoc tests. RESULTS: The comparison between the fitness of the students of the schools, showed differences in the consumption of VO2 (49.8 vs 48.3 vs 53.5 ml / min / kg, p = 0.001), flexibility (4.5 vs. 3.2 vs 10 cm, p = 0.001), prehensile strength (44.4 vs 37.1 vs 48.3 kilograms, p = 0.001), flight time in the Squat Jump test (481.6 vs 451.1 vs 482.4 milliseconds, P = 0.001), flight time in the Push Up test (404.6 vs 316.7 vs 375.5 milliseconds, p = 0.001), body mass index (23.5 vs 23.7 vs 22.4 weight / height2, p = 0.027) and an absolute value of fat-free mass (56.4 vs 52 vs 56 kg, p = 0.009). CONCLUSIONS: Although the training plan of the Colombian Army is standardized, it was found that there are differences in the fitness of personnel in military training, which could be due to the differences in intensity, volume, duration, density and frequency of training. Supported by internal Grant 001-2017 / Technological Support Command, Ejército de Colombia.