<p>Weight resistance training strains lower back internal structures, potentially leading to acute and overuse injuries. The objective of the present study was to evaluate the influence of using different weightlifting belts on the back kinematics and muscle activities in deadlift and back squat movements. Seventeen weightlifters performed both movements in three conditions: with No weightlifting belt, with a flexible weightlifting belt and with a stiff weightlifting belt. Compared to no weightlifting belt, lumbar lordosis angle was significantly reduced with flexible weightlifting belt (2.7° in deadlift and 3.4° in back squat) and stiff weightlifting belt (5.2° in deadlift and 7.0° in back squat). Lumbar Multifidus muscle activity was also significantly increased with stiff and flexible weightlifting belts in both deadlift and back squat, while Erector Spinae Longissimus and Iliocostalis Lumborum muscle activities were reduced with stiff weightlifting belt in back squat. These outcomes indicate a shift in the load-bearing responsibilities from the mid- to the lower back muscles. Thus, wearing a weightlifting belt might be a good support to stabilize the lumbar area during weightlifting activities, helping to keep the back straighter and to reduce the load on the spine.</p>