Hamstrings: Leg curls?

We suggest that you try an exercise for the hamstrings that outperforms leg curls and can be incorporated into one routine or another.

The standard exercise for the hamstrings is the lying leg curl, which works well and is excellent; however, it can become boring.

At your gym, you can see people training this muscle group on a specific machine that has long been widely used by the best athletes and bodybuilders in the world… but is it the best?…

Some researchers decided to find out by conducting a serious, independent study published by the American Council on Exercise.

The 2018 study answers some questions and draws interesting conclusions about training on leg day.

Hamstrings: comparing the exercises

In this study, 16 bodybuilders—8 women and 8 men—were recruited to perform different exercises for the hamstrings:

• Machine lying leg curl
• Machine seated leg curl
• Barbell Romanian deadlift
• Dumbbell Romanian deadlift
• Machine hip extension
• Nordic hamstring curl
• Kettlebell swing
• Swiss-ball leg curl
• Reverse hip extension

Surface electrodes were placed on each subject to measure their levels of muscle activation, using weights equal to 70% of 1RM.

The thick black line on the graph represents the efficiency value of the lying leg curl, showing that the kettlebell swing slightly outperformed it in terms of biceps femoris activation.

The other measurable muscle in the hamstring group is the semitendinosus, which was evaluated by comparing the leg exercises.

In this case, the Swiss-ball leg curl, reverse hip extension, and Nordic hamstring curl outperformed the lying leg curl.

Since the third hamstring muscle was not tested because it is not possible to place an EMG electrode on and isolate the deep semimembranosus, some conclusions can still be drawn.

A practical application

What does this mean for you? Well, the leg curl machine is excellent and an essential accessory for the hamstrings.

When the data are viewed collectively, they reveal that only two exercises—kettlebell swings and single-arm/single-leg Romanian deadlifts—had similar levels of muscle activation in the hamstring muscle groups compared with the lying leg curl.

We all know that time is essential in the gym, and these results reveal that these three exercises stimulate the hamstrings equally well and can be used interchangeably.

• Kettlebell swings are an excellent option for workouts at home or in the park. Likewise, using a Swiss ball as a complementary exercise to extend the hips and flex the knees can be effective on an autumn afternoon.
• For those who enjoy the gym even when it is cold, instinct—and now science—suggests that the lying leg curl efficiently isolates the specific muscles; you can also combine it with single-arm/single-leg Romanian deadlifts.

Many of the other exercises can be very difficult to perform and, even if your trainer tells you otherwise, you now know which exercises are key to getting the maximum benefit for your hamstrings.