Dumbbell Straight-Leg 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 lower legs, which extend forward, back into alignment above the ankles when you stand up and also provide stability throughout the entire movement.
The quadriceps work hard to extend the knees.
The hamstrings and glutes work to bring the torso upright by aligning the thighs and back.
The erector spinae, which runs along the spine, helps straighten the back.
The abdominal muscles mainly provide stability (the rectus abdominis acts as an antagonist to the erector spinae and the oblique abdominals act as a brake on lateral tilting).
The muscles in the upper back and neck engage to pull the shoulders up and back.

In the straight-leg deadlift, also known as the stiff-legged deadlift, the emphasis is different. The legs remain almost straight, so the quadriceps are barely active (only to provide stability). 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.

Dumbbell straight-leg deadlift execution

1
Push your glutes back and your chest forward. As you do so, arch your back slightly more than its natural curve. Keep your knees almost straight.
2
Continue until you feel as much stretch in the hamstrings as possible.
3
Raise yourself again by pushing your pelvis forward and lifting your back (see notes). Continue until your back is upright with its natural curve. Just as when you normally stand upright. Do not extend it too far and therefore do not create an exaggerated curve in your back at the end of the movement (no hyperextension).
4
Repeat.

Dumbbell straight-leg deadlift

Involved muscles:

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

Abdomen:

Rectus abdominis (rectus abdominis muscle)
Obliquus externus abdominis (external oblique muscle)
Obliquus internus 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

Dumbbell straight-leg deadlift setup

Stand with the dumbbells in your hands, the dumbbells close in front of your legs and your palms facing backward.
Place your feet between hip-width and shoulder-width apart.
Tense your abdominals and glutes like a natural weightlifting belt to protect your back.

Dumbbell straight-leg deadlift technique

The straight-leg deadlift is better compared to a good morning than to a conventional deadlift. The emphasis is much more on the hamstrings, lower back, and glutes than on the quadriceps.

The farther you tilt forward, the greater the stretch on the hamstrings. The same applies to how straight you keep your legs. To keep your legs (almost) straight and avoid falling forward, move your glutes back from the ankles (and therefore not the knees).