The paper aims to analyze the potential injuries induced by the seat belt in case of triggering the pretensioning mechanism. Two mannequins, with different geometries, have been installed on the front seat of the vehicle and were subjected to the efforts generated by the pretensioning of the seat belt, in the absence of an impact of the vehicle. The force due to the impact has been analyzed in various bibliographic resources, in the proposed model it can be taken into account. Efforts were measured in the belt strap for adult passenger and adult pregnant female passenger, or adult passenger with high BMI body mass index. The efforts that act on the human body, with emphasis on the abdominal loop, have been determined. It has been found that stress on the abdomen can cause internal damage, even just by simply triggering the pretensioning system, without taking into account the force on the body due to the impact.