Many great exercises work the hamstrings. But if you spend time training one muscle group, you want to do only the best exercises, right?

A recent study conducted at the University of Memphis looked at the Leg Curl, Good Morning, Glute-Ham Raise and Romanian Deadlift (RDL) to find out which of these common exercises best work the hamstrings.

The researchers hypothesized that the Leg Curl would produce results similar to those of the Glute-Ham Raise, and that the Good Morning would do the same in relation to the RDL, because the pairs work the same movement patterns.

Twelve men with weight room experience performed each exercise at random for one rep at 85 percent of their max. Surface electromyography sensors were attached to the biceps femoris, semitendinosus and semimembranosus—the three muscles of the hamstrings—to determine levels of muscle activity.

Surprisingly, they found that the RDL and Glute-Ham Raise best activated the hamstrings. However, the results go a bit deeper.

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The RDL and Glute-Ham Raise maximized activation of the biceps femoris. Activation of the semitendinosus and semimembranosus was highest concentrically (i.e., in the upward portion of the exercise) during the Glute-Ham Raise, and eccentrically (i.e., in the lowering portion of the exercise) during the RDL.

These results suggest that the most effective way to train your hamstrings is to incorporate both the RDL and Glute-Ham Raise into your training, because they complement each other to hit the entire muscle group. The other exercises are still effective, but they don’t offer as much benefit for your time.

If you’re unfamiliar with the RDL and Glute-Ham Raise, here’s how to perform them. These are challenging moves, so don’t do them together in the same workout.

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Romanian Deadlift

• Stand with your feet hip-width apart holding a barbell in front of your thighs.
• Keeping the barbell close to your body and your back straight, sit your hips back to lower the barbell to mid-shin level.
• Extend your hips to stand up and return to the starting position.

Variations: Dumbbell RDL, Dumbbell Single-Leg RDL

Glute Ham Raise

• Position yourself on the glute-ham machine with your legs locked in place and your torso upright.
• Lower your torso until it’s parallel to the floor. Have a partner provide assistance if needed.
• Drive your knees into the foam pad until they are at a 90-degree angle and your body is upright.

Variations: Nordic Hamstring Curls