Provided your technique is correct and you start out with a comfortable weight and build up gradually, you will become stronger and more resilient so your body will be able to withstand the spinal compression without sustaining any damage. But compressive forces are not the major issue here – it’s shear force, or the force that is applied to your spine at an angle, that causes excessive strain on the lower back.
The role of many elements of the proper deadlifting form, such as keeping an erect torso and not allowing the bar to drift away from the body, is to minimize shearing force. As you can already guess, the most common reason for back injury while performing deadlifts is the combination of compressive and shear forces, which happens as a result of poor form and weak lower body muscles.
To avoid this, watch your form. Bend down to grip the bar but push your hips back, keeping your torso as close to vertical as possible and your shoulders behind the bar. As you stand up with the bar, push your shoulders back. Avoid rounding your back at all times. If you still have a problem with handling the shearing force on your lower back, switch to sumo or trap bar deadlifts. The sumo variant involves a wider foot placement, which makes it easier to maintain a flat back, while trap bar deadlifts involve the least amount of shear force and are most suitable for people with lower back problems.
There’s a notion floating around that sumo deadlifts are easier than conventional deadlifts and should be even considered as cheating, mainly because there’s a difference in the hip extension torque required to lift the weight.
However, that’s not true. Simply put, sumo deadlifts are harder on your quads, while conventional deadlifts are harder on your hams and spinal erectors. If you don’t know your weaknesses, do both variants for a couple of months and notice the way you feel and the results you get. If your sumo max is higher than your conventional deadlift max, then odds are that your back is weak. On the other hand, if your conventional max is higher, even though your sumo feels better with lighter loads, chances are that your quads need more work.
When it comes to the trap bar, keep in mind that no serious lifter will ever ask you how much you trap bar deadlift – it’s just nowhere near as impressive as the conventional or even sumo variant. However, if developing max strength isn’t your primary goal, if you have lower back problems or if you simple lack the mobility to properly pull off sumo or conventional deads at the time being, go for the trap bar. In addition, trap bar deadlifts can be the best choice for someone concerned primarily with fat loss.
In terms of carryover, a wider stance will generally carry over into a narrow stance more effectively than the other way around. You will experience a great transfer between trap bar and sumo deadlifts, and between sumo and conventional deadlifts.
You can certainly achieve impressive results with any deadlift version, and we encourage you to experiment with all of them and see which works best for your body type and personal goals. That being said, a good rule of thumb is to train the variant that allows you to work on your weakest areas. If you get to know your weak links and then target them properly, always striving to perfect your form in the process, you’re guaranteed to experience powerful progress.