By Michael Joseph, DPT Student
The deadlift is one of the most effective and widely used exercises to build raw strength. There are many variations of the deadlift, including conventional deadlifts, sumo deadlifts, stiff leg deadlifts, Romanian deadlifts, and the popular hex bar deadlift (HBD). As opposed to a straight bar deadlift (SBD), where the bar is sitting in front of the body, this bar allows the lifter to stand within a hexagon-shaped frame and lift the weight from the ground. But, what is the difference between a straight bar and a hex bar? And why would you use one instead of the other?
Research
In a study by Swinton et al, a group of competitive powerlifters were recruited to compare the biomechanical differences between the SBD and HDB. Subjects tested their 1 rep max and submaximal lifts on both bars. 3-D motion analysis was used to measure body position and velocity and acceleration of the bar. The study found the powerlifters were able to lift an average of 45 lbs. more using the hex bar, compared to the straight bar. In addition, across submaximal loads deadlifts using the hex bar produced greater peak force, peak velocity, and peak power compared to the straight bar. This suggests that the HBD is a more effective exercise due to the greater mechanical stimulus produced during submaximal loads. 
A follow up study was done by Camara et al, comparing electromyography, force, velocity, and power characteristics between the two bars. Surface EMGs were placed on the vastus lateralis (quadriceps), biceps femoris (hamstrings), and erector spinae (low back) muscles. Force, velocity, and power were measured by attaching a velocity transducer to the barbells. This study also measured subjects’ 1 rep max and submaximal loads. EMG results found greater quadriceps activation during the HBD, but greater hamstrings and low back activation during the SBD. However, there was not a significant difference in the 1 rep max lifts. This study also confirmed higher peak velocity, peak force, and peak power with the HBD than the straight bar deadlift.
Clinical Application
Both studies confirm the SBD puts greater stress on the hamstrings and low back, while the HBD distributes loads more equally, putting greater stress on the quads. For individuals with low back pain or who are rehabilitating a low back injury, using a hex bar to deadlift may be a safer alternative to using a straight bar. Similarly, for a patient who may not be ready to perform a loaded squat, the HBD may be used as an effective alternative to strengthen the quadriceps. 
Both studies also agree that the HBD produced greater peak force, velocity, acceleration, and power. This suggests the HBD is a better exercise for overall strength training. The HBD may be a more beneficial deadlift variation than the SBD for athletes because it is more effective for improving overall strength, while putting them at less risk of a low back injury. So when should the SBD be used for patients and athletes? If the goal is to strengthen hamstrings and low back extensors specifically, the SBD will be more effective. Similarly, if the SBD is specific to the athlete’s sport, (for example, powerlifting or CrossFit) training the SBD may be more beneficial.
Blog Post written by Michael Joseph, DPT Student at Mount Saint Mary’s University. Michael is currently in his final Clinical Rotation with me at Catz Physical Therapy Institute.
References
- Swinton PA, Stewart A, Agouris I, Keogh JW, Lloyd R. A biomechanical analysis of straight and hexagonal barbell deadlifts using submaximal loads. J Strength Cond Res. 2011;25(7):2000-9.
- Camara KD, Coburn JW, Dunnick DD, Brown LE, Galpin AJ, Costa PB. An Examination of Muscle Activation and Power Characteristics While Performing the Deadlift Exercise With Straight and Hexagonal Barbells. J Strength Cond Res. 2016;30(5):1183-8.
Chris Butler Sports PT 