The main aim of the study is to propose an approach for 3D modeling and simulation of swimmers impulse during a grab start. Four national level swimmers were investigated. For every swimmer, 3D model was generated in BRG.LifeMOD TM on the base of individual morphologic parameters and kinematic data obtained by high speed video camera and passive markers attached at the level of each important articulation. The proposed approach allows predicting swimmer's joint moments for each important articulation during the impulse phase of the grab start and to analyze the segmental coordination for each studied swimmer in order to optimize the performance. The model was successfully validated by comparing the predicted speed and power values with experimental ground reactions data collected in situ.