First off, positioning is different. For barbell deadlifts, one stands behind the bar and grasps it in a squatted position. Whereas, you have step into the hex bar and grasp the bar at the sides. This allows for a more upright position when doing hex bar deadlifts. This may be an obvious observation to those familiar with both exercises, so let’s talk about how this difference changes the stress put on the body.
Due to the positioning of the bar on barbell deadlifts, the load is farther away from the body. This is important to note because the farther away you hold an object away from the body, the more force (shearing) is placed on the spine. Alternatively, the closer one holds an object to their body the more evenly distributed its weight is over the joints in the body.
Swinton el al. found that when comparing the two exercises the hex bar deadlift placed less torque on the lumbar spine, hips and ankles, but an increase on the knee. This study was conducted using in 19 male powerlifters. Interestingly, they found that the men could lift more weight performing hex bar deadlifts than when doing barbell deadlifts. However, this isn’t always the case.
Camara et al. recruited 20 men with weight-lifting experience who could lift 1.5 times their body weight when doing barbell deadlifts. On separate days, they had subjects perform barbell or hex bar deadlifts for 3 reps using a load of either 65 or 85% of their one-rep max (1RM). What they found was that there wasn't much difference in weight used when using a hex or straight bar at either 65% or 85% of the subject's 1RM.
The difference between the two studies may be explained in the subject’s familiarity of the exercises. The Swinton study used competitive powerlifters and it's thought that they may have had more experience doing hex bar deadlifts than the subjects in the Camara. Who knows for sure tho.
Anyways, in the Camara study, the researchers attached electrodes to one of the muscles in the quads (vastus lateralis), hamstrings (biceps femoris) and lower back (erector spinae) to measure muscle activity during the concentric (lifting) and eccentric (lowering) phase of the exercises.
What they found was that the hex bar caused greater activation in the quads (vastus lateralis) on both phases of the lift. While the barbell deadlift displayed greater activation in the hamstrings (bicep femoris) during concentric phase and in the lower back (erector spinae) during the eccentric phase.
Finally, in a third study comparing the concentric (lifting) phases of the two exercises, researchers placed electrodes on the hamstrings (biceps femoris), lower back (erector spinae) and glutes (gluteus maximus) of 13 resistance-trained men. The men did a series of warm ups and then a one-rep max for each exercise.
What they found was that barbell deadlift displayed significantly greater activation in the hamstrings, just like in the Camara study. They also found that the concentric phase of the lift did not show a significant difference in muscle activity for the erector spinae. There were also no significant differences in the glutes between the exercises.
Summing It All Up
For those of you who are new to deadlifting or coming back after a long layoff or who have lower back issues then you may want to start off with hex bar deadlifts. Most hex bars have the option of using the higher grip, which allows you to be in a more upright position. This can come in handy if you have poor ankle and hip mobility (I’d still work on improving your mobility tho). On the other hand, if you're looking to build/strengthen your lower back and hammies then you may want to incorporate barbell deadlifts into your training program.
For more information:
1. Swinton, PA. et al. A Biomechanical Analysis of Straight and Hexagonal Barbell Deadlifts Using Submaximal Loads. J Strength Cond Res. 2011 Jul;25(7):2000-9
2. Camara, KD. et al. An Examination of Muscle Activation and Power Characteristics While Performing the Deadlift Exercise With Straight and Hexagonal Barbells. Journal of Strength and Conditioning Research. 2016. May. Vol 30. Issue 5. 1183–1188.
3. Andersen, V. et al. Electromyographic Comparison Of Barbell Deadlift, Hex Bar Deadlift And Hip Thrust Exercises: A Cross-Over Study. J Strength Cond Res. 2017 Jan 30.