There are a number of coaches and training styles that recommend only singles in Deadlift training. This always confused me. Why should you treat the Deadlift any different than the Squat, or the Bench for that matter? Most proponents never provide an answer that I’ve been satisfied with. After training the deadlift almost exclusively with singles for a bit, I think I have a decent answer.
If you’re concerned about lumbar flexion then the Deadlift has the greatest potential to produce lumbar flexion. In fact, the majority of Conventional Deadlifts have lumbar flexion when they Deadlift. Most say they only round the upper back but look for lumbar extension when they lockout. It’s a sure sign they had lumbar flexion.
If you have decent control over your lumbar then you should have no problem doing reps. However, if like many, you tend to round your back when deadlifting then doing reps just increases the potential for rounding. Can you control your lumbar for just one rep? If the weight’s not too heavy it’s likely you can. If you do round your lumbar, albeit rarely, it’s likely to cause more disruption/soreness to the low back area than those who pull rounded always.
Because of the potential to round the lumbar as you fatigue in the Deadlift we could consider the Deadlift the movement with the most potential for “catastrophic” form breakdown. Therefore anything we do to mediate that potential will be advantageous. Singles are a good way to prevent this form breakdown. Not that there will never be lumbar flexion during singles but it’s much easier to allow for some flexion when you’re doing multiple reps in the Deadlift.