In strength coaching circles, there’s a highly effective hamstring exercise that is well known to coaches, athletes, and sports medicine personnel.
The exercise has many names, including the Russian leg curl, Russian lean, Russian ham curl, kneeling Russian hamstring curl, Nordic ham curl, Nordic hamstrings, Nordic hamstrings lower, Nordic leg curl, Nordic reverse curl, glute-ham curl, bodyweight leg curl, natural hamstring curl, and bodyweight hamstring curl. The most common name used in the literature is the Nordic ham curl (NHC).
These exercise variations typically involve kneeling on a pad and lowering under control while the ankles are held in place by a partner, a lat pulldown apparatus, a sit-up apparatus, a loaded barbell, a poor man’s glute-ham apparatus, or any other immovable object you can think of using. Here’s a video of my sister from several years ago busting out 3 reps.
NHC and Hamstring Strain Injury Prevention
I would guess that the NHC is one of the top ten most studied and referenced exercises in the literature, probably behind squats, Olympic lifts, bench press, push ups, lunges, and deadlifts. In fact, at the end of this article, you’ll see over 100 studies listed. The reason why it is so popular is due to the prevalence of hamstring strain injuries in sports and the belief that the NHC can help prevent them. The eccentric nature of the NHC is believed to increase hamstrings length and shift the maximum strength of the muscle toward longer muscle lengths, which is believed to be important in sports. For more information along these lines, please read:
Questioning the NHC as a Hamstring Injury Prevention Method
If you’re a strength coach or physical therapist, then you should definitely include the NHC in your arsenal. There’s a wealth of research behind it, and there’s no doubt that it can help prevent hamstring strains. Moreover, knee flexion torque is highly correlated with sprint speed, and the hamstrings contract to both extend the hips and flex the knees during sprint running (and this is vital during the window immediately before, during, and immediately after the foot strikes the ground). So knee flexion shouldn’t be omitted in sport training.
But before I delve further, I want to be very clear about something. Possessing high levels of eccentric hamstring strength does not guarantee that hamstring strains will not occur. In Hamstring strain injuries: are we heading in the right direction?, Mendiguchia et al. explain how hamstring strains are predicted by the interrelated nature between flexibility, strength, fatigue, core stability, architecture, and previous injury.
An athlete could possess sound levels of hamstring strength to absorb eccentric stress, sound levels of hamstring flexibility to lengthen sufficiently during high load activity, and sound levels of core stability to prevent aberrant pelvic motion, but still wind up with a hamstring strain due to excessive fatigue, a prior injury, or simply a skeletal anatomy or muscle architecture that lends itself to large strains on the hamstrings.
Furthermore, the NHC works primarily on knee flexion. In sports, the knee joints do not move independently from the hip joints; they work in concert with one another. Moreover, hip extension exercises stretch the hamstrings to a greater degree than knee flexion exercises. Therefore, it is very important to perform hip extension exercises as they will lead to a greater stretch in the hamstrings, and they are more specific to sport movement.
The NHC as a Hamstrings Builder
Can the NHC pack on serious hamstrings muscle mass? I believe it can. Take a look at a study conducted by Ebben et al. which showed that NHCs (in this study they were called Russian Curls or RCs) outperformed seated leg curls, stiff leg deadlifts, single leg stiff leg deadlifts, good mornings, and squats in hamstring EMG activity.
As you can see, the NHC is no joke. Now, there are several articles in the literature investigating hamstring EMG activity, and they show conflicting results, probably because hamstring activation is highly influenced by the precise placement of the electrodes along the length of the muscles. At any rate, the NHC undoubtedly leads to high levels of hamstring muscle activation and should be included in a comprehensive hamstring strengthening protocol, especially in conjunction with other exercises such as Romanian deadlifts (RDLs), glute ham raises (GHRs), and lying leg curls. RDLs, GHRs, and NHCs are well-suited for producing high levels of tension and damage, whereas lying leg curls are well-suited for producing high levels of metabolic stress.
The Band Assisted Nordic Ham Curl: A Better Alternative
In this article, I’d like to impress upon you what I believe is a more effective NHC variation compared to the standard exercise. The vast majority of lifters and athletes are not strong enough to adequately control the lowering portion of the exercise throughout the entire range of motion (ROM). Almost inevitably, athletes lower their bodies under control during the first half of the movement and then sink like a ship during the second half of the movement. This rapid descent is accompanied by a sharp decline in muscle activity.
To prevent this occurrence, the lifter can simply use a band to provide assistance, which kicks in more and more as the lifter descends into the latter portion of the movement. This is importance since the torque angle curve of the NHC is sharp such that the most torque out of the knee flexors is required at the end of the movement when the muscle is lengthened (but it’s important to realize that in a NHC, the hamstrings don’t even reach resting length at their maximum stretch).
Of course, not every athlete needs the band assisted version of the NHC. Take a look HERE at former NFL athlete Adam Archuleta – skip to the 2 minute and 32 second mark and watch Adam bust out NHCs with ease. But guys like Adam are the exception, not the norm.
In the video below, you can see that I’m able to control my body throughout the entire range of motion. In fact, I don’t even have to use my arms to “push up” and provide assistance.
I hope that you give this variation a try, I think you will find it to be more effective than the traditional version, at least until you build up enough strength to sufficiently control your bodyweight during the eccentric phase without the use of bands.
Research on Nordic Ham Curls
Below is a list of over 100 linked journal articles that investigate, program, discuss, or recommend the Nordic Ham Curl exercise.
Development and validation of a questionnaire (FASH—Functional Assessment Scale for Acute Hamstring Injuries): to measure the severity and impact of symptoms on function and sports ability in patients with acute hamstring injuries.