A biomechanical analysis of straight and hexagonal barbell deadlifts using submaximal loads

The purpose of the investigation was to compare the kinematics and kinetics of the deadlift performed with 2 distinct barbells across a range of submaximal loads. Nineteen male powerlifters performed the deadlift with a conventional straight barbell and a hexagonal barbell that allowed the lifter to stand within its frame. Subjects performed trials at maximum speed with loads of 10, 20, 30, 40, 50, 60, 70, and 80% of their predetermined 1-repetition maximum (1RM). Inverse dynamics and spatial tracking of the external resistance were used to quantify kinematic and kinetic variables. Subjects were able to lift a heavier 1RM load in the hexagonal barbell deadlift (HBD) than the straight barbell deadlift (SBD) (265 ± 41 kg vs. 245 ± 39 kg, p < 0.05). The design of the hexagonal barbell significantly altered the resistance moment at the joints analyzed (p < 0.05), resulting in lower peak moments at the lumbar spine, hip, and ankle (p < 0.05) and an increased peak moment at the knee (p < 0.05). Maximum peak power values of 4,388 ± 713 and 4,872 ± 636 W were obtained for the SBD and HBD, respectively (p < 0.05). Across the submaximal loads, significantly greater peak force, peak velocity and peak power values were produced during the HBD compared to during the SBD (p < 0.05). The results demonstrate that the choice of barbell used to perform the deadlift has a significant effect on a range of kinematic and kinetic variables. The enhanced mechanical stimulus obtained with the hexagonal barbell suggests that in general the HBD is a more effective exercise than the SBD.