The deadlift is a common and popular exercise to strengthen the lower body and posterior chain. The typical straight barbell deadlift primarily targets the hips and erector spinae, specifically in the lumbar spine region. This is because the bar is in front of the legs and there is a large moment arm for the erector spinae muscles. However as the weight increases, the amount of stress on the low back can become excessive. Studies have shown that there is greater biceps femoris activity (1 of the 3 hamstring muscles) during the lifting phase and greater erector spinae activity during the lowering phase.
One of the best—albeit uncommon—deadlift variations for (P)rehab and sport performance is the hex barbell, also referred to as the trap bar deadlift. This variation changes the relationship between the body and the bar, thus changing the muscle activation. The hexagon trap bar deadlift increases vastus lateralis activity during the lifting AND lowering phase of the lift. This variation is more like a hybrid of the squat and a deadlift, promoting you to bend your knees more during the exercise. It allows you to stand IN the bar, making the weights parallel with your spine instead of in front of it. This minimizes the torque on the low back compared to the straight barbell deadlift, where the weight is placed in front of your spine.
The best part - studies have shown the hexagon bar deadlift provides an enhanced mechanical stimulus. This specific variation significantly increases peak force, peak power, and peak velocity. With training and time, it has been shown you can lift more and increase your 1RM with the trap bar compared to the straight barbell. Variation provides increased stimulus, and stimulus combined with progressive overloading is how you can get bigger, faster, and stronger.
If you want to target your hamstrings and erector spinae, hit the straight barbell. But if you want to decrease the torque on your low back and target performance specific gains, hit the trap bar. If you want to preserve VELOCITY and FORCE performing this exercise, try out cluster sets (4 sets of 2x5rep clusters - 30s rest between clusters - 90s rest between sets). These parameters have been shown to improve velocity and force and as an added bonus, they help increase performance specific factors with the back squat!
Camara et al. 2016: An examination of muscle activation and power characteristics while performing the deadlift exercise with straight and hexagonal barbells.
Oliver et al. 2016: Velocity drives greater power observed during back squats using cluster sets.