Previous research have been shown that young people are sedentary in major ways, for this reason is possible to find a higher percentage of fat tissue, less muscular mass and an increased incidence of postural alterations. PURPOSE: To describe the relationship between physical capacities, body composition and their effects in the posture of Santo Tomas University’s first semester students in Colombia. METHODS: Seventy-seven subjects (35 Male, 42 Female, 18.5±2.3 yo) were submitted to a body composition evaluation using bioimpedance (BC), postural analysis with the plumbline method (PA) and physical tests: peak oxygen consumption with the multistage 20 meter shuttle run test (VO2), Eurofit Sit Up Test for abdominal endurance (AE) and sit and reach test for flexibility (FX). The differences between men and women were established by means of the Student´s t-test, and the Spearman rho correlations were used to evaluate the relationships between the variables, with significance level of 0.05. RESULTS: The differences between both, men and women using BC were significant: body fat percentage 35.7±7.6 in women vs 20.3±7.7 in men (p<0.05) and muscle mass percentage 25.7±4.0 in women vs 40.4±4.7 in men (p<0.05). On the other hand, men had a greater VO2 44.1±6.5 mL•kg-1•min-1 than women 34.6±3.9 mL•kg-1•min-1 (p<0.05). Men also had better results in PA and AE than women with significant differences, without differences in FX. Although, exists an inverse relationship in the women between muscular mass and PA (r=−0.29 p <0.05), no other variables were associated. Finally, a direct relationship between VO2 and muscle mass (r=0.77 p<0.05) and inverse with the fat tissue (r=−0.76 p<0.05). CONCLUSIONS: The values of VO2 are less than the expected values for the age. In addition, these have a direct association with the body composition (results previously demonstrated in other studies). However, despite the poor relationship that level of postural alteration has with VO2, it might be expected that in the coming years this relationship will increase, along with a higher incidence of non-communicable chronical diseases too. Therefore, it is necessary to increase exercise programs to improve body composition, posture and physical capacities in the University’s students.