Most lifters have always assumed that the Romanian deadlift (RDL) was a tad better for the glutes and hamstrings than the conventional deadlift (CD) because the quads (specifically, the rectus femoris) play such a big role in the latter.
It was a forgone conclusion, like how Eggos are better than English muffins, but no real-deal scientists had ever bothered to compare the two lifts – at least not until some researchers from Western Michigan University looked into it.
The scientists found 21 men with at least three year's experience with both the CD and the RDL. Each subject had a spider web of needles and electrodes affixed to their rectus femoris, biceps femoris, and gluteus maximus.
The lifters then alternated between performing RDLs and CDs, using 70% of their one-rep maximum on both.
They all used standard form on both of the lifts, with one exception: While the typical RDL range of motion usually comes to a halt when you start to feel a mild stretch in the hamstrings (which generally happens when the bar travels just south of the knees), the participants in this study were asked to at least attempt to lower the bar to the floor, flexibility permitting.
To no one's surprise, the CD evoked a much stronger response in the rectus femoris than the RDL – almost double the EMG percentage peak. The researchers also found that the CD caused significantly greater EMG values in the glutes, but this is where we have to take a brief side bar, your honor.
Scientists have an entirely different definition of the word "significant" than lay people. In science parlance, significant is kind of a weasel word that just means the amount was large enough to be noticed, or large enough to matter. It's closely related to the term "statistically significant," which means a difference that's unlikely to be caused by random chance.
However, if you said you had a significant amount of sex last night, it would likely mean something far different than an amount of sex that, when compared to the amount of sex you normally had, was unlikely to be caused by random chance.
So while the CD evoked a "significantly" greater response in the glutes than the RDL, the difference in EMG value in normal, non-science language was just a smidgeon, a duck snort that probably doesn't matter in the long run.
And while the CD came out on top with biceps femoris activation, too, the difference here was even less than we saw with the glutes.
In short, the CD definitely caused the rectus femoris, or predominant quadriceps muscle, to work a lot harder. As far as the biceps femoris (the predominant hamstrings muscle) and the glutes, the amount was pretty much a wash between the two lifts.
The real eye-opener in this study is just how much the CD relies on the rectus femoris, which presents a potential problem: A lot of us split our leg training as part of a push/pull workout, doing quad dominant movements (like the squat, leg extensions, etc.) on one training day and then doing hip-dominant exercises (deadlifts, glute thrusts, etc.) on another.
Since the CD recruits the rectus femoris so heavily, incorporating it into a push/pull workout is problematic. Let's say your push/pull workout includes squats on "push" day and CD's on "pull" day. That means you're working the quads twice as often as you intended.
Given this study and the results described in this article, it would be much more logical and efficient to keep the squats in your push workout but replace the CD with the RDL in your pull workout. The glutes and biceps femoris recruitment is virtually the same as with the CD, but you're getting minimal involvement of the rectus femoris.
If you're going to do RDLs instead of CDs, I suggest you make them count and do them on the Smith machine, as T Nation contributor Paul Carter suggests. (He prefers them to barbell RDLs because the stability afforded by the machine allows you to sit back farther.)
Paul also suggests you do them with with a 5-second eccentric to further accentuate the targeted glutes and biceps femoris. To really maximize recruitment, slap a couple of step platforms underneath the bar and stand on them. This will allow you to extend the range of motion (provided your spine is flexible enough).
A couple of sets of 10 should more than do the trick.
- Lee S et al. An electromyographic and kinetic comparison of conventional and Romanian deadlifts. J Exerc Sci Fit. 2018 Dec;16(3):87-93. PubMed.