Romanian Dumbbell Deadlift

The deadlift is also known as the king of all exercises. Looking at the list of muscles involved above, you can infer why.

The calf muscles bring the forward-projecting lower legs back into alignment above the ankles when you stand up and also provide stabilization throughout the movement.
The quadriceps work hard to extend the knees.
The hamstrings and glutes work to bring the upper body upright by aligning the thighs and back.
The erector spinae, which runs along the spine, helps straighten the back.
The abdominal muscles primarily provide stabilization (the rectus abdominis acts as an antagonist to the erector spinae, while the oblique abdominal muscles act as a brake against lateral tilting)
The muscles in the upper back and neck become active to pull the shoulders upward and backward.

The Romanian deadlift falls between a conventional deadlift and the straight leg deadlift. In the straight leg deadlift the legs remain almost straight, so the quadriceps are barely active (only to stabilize). The hamstrings are stretched more and therefore loaded more. You also bend farther forward from the back, which places more load on the lower back and glutes.

In the Romanian deadlift, the knees are bent slightly more, but not as much as in a conventional deadlift. As a result, the quadriceps are loaded slightly less than in a conventional deadlift, but not relieved as much as during the straight leg deadlift.

Romanian Barbell deadlift execution

1
Move your glutes backward and your chest forward. Make your back slightly more arched than its natural curvature. Allow your knees to bend slightly, but not as far as in a conventional deadlift (approximately halfway).
2
Continue until the barbell almost touches the floor (or until you feel the greatest possible stretch in your hamstrings).
3
Raise yourself again by driving your pelvis forward and extending your back (see notes). Continue until your back is upright with its natural curve, as when you normally stand upright. Do not extend it too far, and do not create an exaggerated curvature in your back at the end of the movement (no hyperextension).
4
Repeat.

Romanian Barbell deadlift

Muscles involved:

Legs:

Hamstrings
Quadriceps (vastus lateralis, vastus medialis, vastus intermedius, and rectus femoris)
Sartorius

Glutes:

Gluteus maximus, medius, and minimus

Pelvis:

Iliacus (hip flexor)
Psoas major (hip flexor)

Calves:

Gastrocnemius
Soleus

Abdominals:

Rectus abdominis (rectus abdominis muscle)
External oblique abdominis (external oblique muscle)
Internal oblique abdominis (internal oblique muscle)
Transversus abdominis (transverse abdominal muscle, ‘corset muscle’)

(Lower) back and spine:

Erector spinae
Lumbar multifidus
Quadratus lumborum

Back and neck:

Trapezius
Rhomboideus
Levator scapulae

Romanian Barbell deadlift setup

Make sure any plates on the barbell are securely locked in place.
Stand directly in front of the barbell with your feet between hip- and shoulder-width apart.
Bend your knees and grasp the barbell with your hands slightly wider than shoulder-width apart. For a secure grip, it may be helpful to hold the barbell with one palm facing forward and the other palm facing backward. Wrist straps may be advisable with heavier weights.
Make sure your knees point in the same direction as your feet.
Maintain the natural curvature of your back. Do not round it, but do not overarch it either. To help with this, avoid staring tensely straight ahead (which quickly causes an excessive arch), and do not look straight down at the barbell (which quickly causes rounding). Choose a point on the floor diagonally in front of you.
Brace your abdominals and glutes like a natural weightlifting belt to protect your back.
Drive your heels firmly into the floor to bring yourself up. Keep the barbell as close to your shins as possible. This is your starting position

Romanian Barbell deadlift technique

The Romanian deadlift places more emphasis on the hamstrings, lower back, and glutes than the conventional deadlift.

The farther you lean forward, the greater the stretch on the hamstrings. The same applies to how straight you keep your legs. To prevent bending your legs farther than desired and to avoid falling forward, move your glutes backward from the ankles (not the knees).