The power teaching career loves experimenting with fads that promise to provide athletes an edge. We transitioned by means of Nautilus machines within the ’70s, bounce sneakers within the ’80s, slideboards within the ’90s…and now we have now the Nordic curl. Lastly, the reply to stopping hamstring pulls, notably in sprinters.
Not so quick.
Don Chu, PhD, an achieved bounce coach and one of many foremost consultants on plyometrics, launched me to Nordic curls within the early ’80s throughout his weight coaching class. The train not too long ago acquired a strong jumpstart within the basic health inhabitants when Ben “Kneesovertoesguy” Patrick started selling it as a part of his knee rehab program. Patrick has constructed an enormous following, with greater than 1.3 million YouTube subscribers and an look on the Joe Rogan present.
The fundamental Nordic curl begins with you kneeling on the ground/floor with a coaching companion anchoring your toes (see picture 1 beneath). It is best to place a towel or pad below your knees for consolation. One suggestion I discovered from German sports activities scientist Dr. Tobias Alt is to increase your knees over the sting of the pad to allow the patella to glide simply (see lead photograph at prime). You may place your arms throughout your chest or at your sides, however one of the best ways is along with your arms bent in a push-up place. This place makes it simpler to catch your self on the backside and preserve excessive hamstring activation on the finish of the motion.
Together with your higher legs perpendicular to the ground and your torso upright, slowly decrease your legs and torso as a unit, catching your self along with your arms when you possibly can not management the motion. When your arms contact the ground, instantly straighten your arms explosively (corresponding to with a push-up) to return to the beginning.
The Nordic curl’s resistance curve is such that it’s rare for an athlete who has not trained on it for an extended period to perform it without collapsing at the midway point. Click To Tweet
The train’s resistance curve is such that it’s uncommon for an athlete who has not educated on it for an prolonged interval to carry out it with out collapsing on the halfway level, a lot much less return to the beginning with out help. In Dr. Chu’s weight coaching class, one elite male lengthy jumper might do it, and an elite feminine discus thrower who grew to become a nationwide weightlifting champion and American report holder acquired shut.
To progress within the train, you possibly can place a low platform in entrance of you to lower your vary of movement, decreasing the peak of the platform as you get stronger. There are additionally methods to change the resistance curve to match your power curve, corresponding to utilizing an elastic band, as proven in picture 1. Because the band stretches, it gives help on the finish vary.
For weight rooms with a wholesome price range, plate-loaded Nordic curl machines regulate to your power curve to allow a smoother movement. The most effective recognized is the Westside Inverse Curl machine®, patented and promoted by powerlifting legend Louie Simmons. The machine’s counterbalanced arm has a padded bar that rests in entrance of the chest, permitting you to extend the burden incrementally to make the motion simpler.
On the superior stage, resistance will be elevated by holding a weight plate throughout the chest or carrying a weighted vest. As a result of the train is so difficult, at first, extra resistance would possibly solely be used in the course of the reducing part (after which launched in the course of the concentric part).
Earlier than discussing a number of the peer-reviewed analysis on the Nordic curl, let’s take a look at one concept about why the train can adversely have an effect on sprinting capacity and enhance the danger of hamstring accidents.
Nordic Curls and the Velocity Lure
Probably the most outspoken critics of the Nordic curl is weightlifting sports activities scientist Andrew “Bud” Charniga. Charniga says that though the train might have worth for bodybuilding functions, athletes shouldn’t do it. His central argument relies on the anatomy of the calves and their perform.
The 2 major calf muscle groups are the gastrocnemius (higher calf) and soleus (decrease calf). Charniga says the gastrocnemius must be thought of a thigh muscle as a result of it overlaps the knee and contributes to knee flexion. These elements have implications for getting extra out of stretching and muscle-building exercises. Let me clarify.
For stretching, within the early ’90s, I attended a hands-on seminar by Bob Anderson in Colorado Springs. Anderson is the creator of Stretching, which offered greater than 33 million copies. Anderson advised us that tightness within the calves is without doubt one of the limiting elements to stretching the hamstrings. Subsequently, it is sensible to stretch the calves earlier than stretching the hamstrings.
For muscle constructing, Canadian power coach Charles Poliquin would use this information of purposeful anatomy to extend the work of the hamstrings throughout leg curls.
As a result of you possibly can decrease extra weight than you possibly can raise in leg curls, the train’s eccentric (reducing) part is just not loaded maximally. To get round this limitation, Coach Poliquin would have you ever raise the burden along with your toes dorsiflexed (toes pulled up) to allow the gastrocnemius to help with knee flexion. Then, you’d decrease it along with your toes plantarflexed (toes pointed down) to lower the work of the calves and enhance the work of the hamstrings.
As proven by these two examples, understanding the anatomical construction of the calves can enhance your capacity to stretch and strengthen the hamstrings. Nonetheless, from a motor studying perspective, Charniga contends that the Nordic curl is a horrific train for sprinters.
Charniga says most hamstring accidents in sprinting happen in the course of the late swing part when your entrance leg is prolonged and nearly to the touch the bottom. At this level, the lengthy head of the biceps femoris completes the longest stretch of the three hamstring muscle groups (the others being the semitendinosus and semimembranosus). How can the hamstrings chill out to increase the knee when the calves contract to provide the alternative impact? It may well’t—one thing should give, and that’s normally the hamstrings.
There’s probably no harm in occasionally performing the Nordic curl as a novelty challenge. However, its risks versus rewards may not be acceptable, especially for high-level athletes. Click To Tweet
There may be in all probability no hurt in sometimes performing the Nordic curl as a novelty problem, corresponding to with my expertise in Dr. Chu’s class. Nonetheless, the dangers versus rewards of this train is probably not acceptable, particularly for high-level athletes. Let’s take a look at some analysis.
The Age of Misinformation
Many web influencers have made extraordinary claims about the advantages of the Nordic curl, backing their claims with analysis research. Nonetheless, let’s learn past the abstracts, beginning with a meta-analysis on soccer accidents and the Nordic curl, which had this brain-teasing title: “Impact of Harm Prevention Packages that Embody the Nordic Hamstring Train on Hamstring Harm Charges in Soccer Gamers: A Systematic Assessment and Meta-Evaluation.”
A meta-analysis makes the research on a subject simpler for the reader by reviewing the outcomes of quite a few research. The researchers of this research concluded: “Groups utilizing damage prevention packages that included the NH (Nordic hamstring) train lowered hamstring damage charges as much as 51% in the long run in contrast with the groups that didn’t use any damage prevention measures.” Spectacular, however questions come up whenever you look intently on the Strategies part.
Solely 5 research met the researcher’s necessities of the research, and in just one was the Nordic curl the one intervention (so, not so “meta”). Right here is an instance of the intervention protocol in one of many research accepted for his or her evaluate:
Hamstring Intervention Exercise
Preliminary Operating Drills
-
Jog
Hip-In
Hip-Out
Circle Companion
Shoulder Contact
Reduce up and Again
Workout routines
Eccentric Hamstring (Nordic Curl)
-
Single-Legged Steadiness
Squats
Jumps
Ultimate Operating Drills
-
Dash
Bounding
Reduce Facet-to-Facet
With so many workout routines, how can anybody conclude that Nordic curls made a distinction? Maybe a discount in accidents occurred regardless of doing the Nordic curl, a priority identified within the researcher’s feedback: “As a result of we didn’t quantify physiologic variables, we can not adequately decide the mechanism of decreased damage danger or establish the simplest a part of the intervention program.” As for the only research the place the Nordic curl was the one extra variable, the outcomes had been underwhelming as a result of the researchers discovered that the Nordic curl “doesn’t cut back hamstring damage severity.”
Many different research on the Nordic curl have been carried out, however some should be checked out with skepticism. Based on a 2022 evaluate by Dr. Alt, “assessments and interventions suffered from imprecise reporting or missing info relating to NHE (Nordic Hamstring Train) execution modalities and subsequent analyses.”
I requested Dr. Alt to increase on his opinion of the Nordic curl, and he replied, “The traditional Nordic curl doesn’t evoke the complete potential the way in which most individuals carry out it, as solely 30 p.c of generated impulse is allotted to the primary 45 levels of knee extension…Alternatively, prolonged knee angles must be addressed with excessive depth for appropriate efficiency enhancement and efficient damage prevention through help or steerage.”
One other issue to think about is that despite the fact that most power coaches know in regards to the Nordic curl train (and plenty of are conversant in the analysis supporting it), the place are real-world success tales?
Even though most strength coaches know about the Nordic curl exercise (and many are familiar with the research supporting it), where are the real-world success stories? Click To Tweet
In soccer, contemplate the outcomes of a 2022 research involving 3,909 soccer gamers from 54 groups in 20 European international locations from 2001 to 2022. Quite than lowering, the researchers discovered that hamstring accidents doubled throughout this era and that over the past eight seasons, “hamstring damage charges have elevated each in coaching and match play.”
In American soccer, why haven’t hamstring accidents decreased within the NFL over the previous decade? On common, about two dozen NFL gamers are sidelined each week in-season resulting from hamstring accidents. For instance, 43 soccer gamers had been sidelined with hamstring accidents earlier than the beginning of the 2019 season, and between the 2018 and 2019 seasons, about 25 athletes couldn’t play every week resulting from hamstring accidents. This development continues at present; for instance, Charniga found that in one week in October 2023, 48 NFL gamers had been sidelined with hamstring accidents.
However It Works…or Does It?
Once more, with all of the glowing testimonies in regards to the Nordic curl with the ability to bulletproof the hamstrings towards damage, why are hamstring accidents so prevalent and rising in some sports activities? In case you want extra convincing with “evidenced-based apply” arguments, listed here are 5 extra variables to rethink the worth of the Nordic curl:
1. Biomechanics
Gestalt is the idea that the sum of the components is just not as nice as its organized complete, and in sports activities, gestalt might translate into “every part is related.”
The Nordic curl isolates one function of the hamstrings: knee flexion. This may be great if you’re a bodybuilder, but it’s not how the legs work in sprinting. Click To Tweet
The Nordic curl isolates one perform of the hamstrings: knee flexion. This can be nice for those who’re a bodybuilder, however it’s not how the legs work in sprinting. As confirmed by researchers in a single 2018 Particular Communication in Medication and Science in Sports activities and Train, “Accordingly, the hamstrings are stretched at each the knee and the hip joints throughout sprinting, however they’re solely stretched on the knee joint throughout NHE.”
As with the leg extension that isolates knee extension, the inflexible knee flexion movement is just not duplicated in sports activities, as concluded by one analysis 2019 research on Australian Guidelines Soccer (ARF). “The [NHE] motion doesn’t replicate what is required in the true world for ARF” and must be “included in a hamstring damage prevention program on this code with warning.” I might add that the mounted nature of the train immobilizes the muscle groups of the ankle utilized in working and leaping.
2. Power Manufacturing
The Nordic curl is carried out slowly, so despite the fact that muscle mass will be elevated, the elastic properties of the connective tissues will not be used to extend power manufacturing. The extended time below rigidity that happens in the course of the train modifications the group of the contractile elements of muscle fibers (pennation angle), decreasing a muscle’s capacity to provide power rapidly.
In high-velocity actions corresponding to sprinting, power is produced briefly, adopted by a chronic interval of leisure. “Sprinters are elastic, pulsating athletes. The quickest sprinters are the quickest relaxers, that means they get their muscle groups to fireside up rapidly after which chill out rapidly,” says backbone biomechanics professional Dr. Stuart McGill. “The identical goes for weightlifters. Russian sports activities scientist Leonid Medvedev confirmed that the muscle groups of elite weightlifters chill out six occasions quicker than the typical Muscovite strolling across the road.”
For these causes, the Nordic curl must be regarded primarily as a bodybuilding train, not an train to develop athletic health. Let’s take a look at some analysis.
Power is measured by the equation: Power = Mass x Acceleration, and peak forces in sprinting can attain 8x physique weight. Though the Nordic curl is prescribed to cope with the high-velocity forces that happen in sprinting, researchers who evaluated the Nordic curl concluded in a 2021 research, “General, peak hamstring power throughout NHE (Nordic Hamstring Train) was not similar to the height hamstring power throughout sprinting.” There’s extra.
One 2019 research examined how the Nordic curl affected dash efficiency. The researchers concluded, “The NHE group reported trivial enhancements in dash efficiency,” and “dash coaching additionally produced higher perceptions of soreness than the NHE.” Then there’s a 2017 research the place researchers discovered {that a} six-week Nordic curl intervention program elevated muscle mass however “didn’t considerably enhance eccentric hamstring power as anticipated.” In different phrases, the NHE doesn’t enhance dash efficiency or develop eccentric power in addition to sprinting does. Moreover sprinting, sprinting, and sprinting some extra (which will be impractical in cold-weather environments), one different is flywheel coaching.
In other words, the Nordic curl doesn’t improve sprint performance or develop eccentric strength as well as sprinting does. Click To Tweet
As a result of eccentric contractions produce the very best muscle contractions, a flywheel gadget can present eccentric overload to attain these peak forces by multiplying the power achieved in the course of the concentric contraction. Video 1 reveals a kBox getting used to provide eccentric overload quickly, one carried out with out help and the opposite with help. Artur Pacek, MS, CSCS, PhD candidate, an elite power coach from Poland who has labored extensively with Knox and his athletes, produced the movies and the info.
What’s distinctive about these two movies is that they present how enhancing stability—on this case, holding onto a barbell—can enhance power manufacturing. The non-supported model might be thought of extra sport-specific, as the steadiness would switch higher to lateral actions, however the supported model would produce extra power. Thus, a exercise to do each might start with unsupported squats and end with supported squats to extend power manufacturing.
Video 1. Flywheel resistance coaching units can present excessive ranges of an eccentric load to cope with the excessive forces that happen in sprinting. This evaluation reveals that increased power ranges will be achieved within the squat when athletes enhance their stability by holding onto a sturdy object. (Movies courtesy Artur Pacek, MS, CSCS, PhD candidate)
3. Vary of Movement
Some web health influencers declare the Nordic curl strengthens the hamstrings by means of a full vary of movement. It may well’t. The Nordic curl begins along with your thighs perpendicular to the ground, so it can not work the biceps femoris by means of an entire vary of movement.
Some internet fitness influencers claim the Nordic curl strengthens the hamstrings through a full range of motion. It can’t. Click To Tweet
In distinction, contemplate the supine leg curl with cables and curler boards that allow the heel to the touch the glutes within the peak contracted place proven in picture 5: workout routines that can be carried out with flywheel models. One benefit of those variations is the working leg will be rotated internally and externally fairly than being held inflexible in a single motion sample as with the Nordic curl. Altering the strains of pull permits for extra full muscular growth. In addition they don’t limit the motion of the patella as happens with the traditional Nordic curl.
Additionally, as a result of gravity applies power vertically downward, there isn’t any resistance till a number of levels of movement are achieved. In case you observe the coaching of elite bodybuilders, it’s typically characterised by partial-range workout routines. Partial-range workout routines, well-liked with bodybuilders to overload all factors of an athlete’s power curve, additionally change the pennation angle, affecting the power of the hamstrings to exert power.
4. Athletic Testing
The Nordic curl is sometimes used to check power, however what muscle groups does the train take a look at? Is the train testing the power of the calves or the hamstrings, and what are the contributions of every? Additional, in what athletic actions is that this movement duplicated? What sport is carried out from a kneeling place with the decrease limbs and ankles immobilized—kayaking?
5. Knee Stress
In comparison with multi-joint workout routines the place stress is distributed over many constructions, the Nordic curl is an isolation train specializing in a single construction. Energy coach and posturologist Paul Gagné addresses this matter. Gagné has educated greater than 500 NHL gamers and labored with Dr. Man Voyer, a well-known osteopath who gave seminars on knee accidents (which I attended), and he’s not a fan of Nordic curls.
“The popliteus (a serious muscle concerned in knee stability) will get actually hammered, particularly on the backside place the place the knee has no give,” says Gagné. “I’ve hardly ever seen folks with good approach. They lack management on the backside of the motion—it’s harmful.” He provides that the Nordic curl locations a excessive stage of stress on the meniscus and a continual irritation situation known as Housemaid’s Knee (prepatellar bursitis).
Don’t Purchase What They’re Promoting
Social media has given us entry to appreciable details about athletic health coaching, however the draw back is that a few of what we learn, see, and listen to is misinformation. It’s one factor for a well-liked web influencer (and even a analysis research) to recommend that an train will produce outstanding ends in athletic efficiency and cut back damage, however then there’s actuality. Such is the case with the invoice of products we’ve been offered with the Nordic curl.
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References
Alt T, Private Communication, 1/4/24.
Charniga B. “Hamstring Harm: Prophylaxis Fallacies in Sport,” Sportivnypress.com, 6/29/21.
Al Attar WSA, et al. “Impact of Harm Prevention Packages that Embody the Nordic Hamstring Train on Hamstring Harm Charges in Soccer Gamers: A Systematic Assessment and Meta-Evaluation. Sports activities Medication. Might 2017;47(5):907–916.
Alt T, et al. “Quo Vadis Nordic Hamstring Train-Associated Analysis? – A Scoping Assessment Revealing the Want for Improved Methodology and Reporting.” Worldwide Journal of Environmental Analysis in Public Well being. September 7, 2022;19(18).
Ekstrand J. “Hamstring damage charges have elevated throughout latest seasons and now represent 24% of all accidents in males’s skilled soccer: the UEFA Elite Membership Harm Examine from 2001/03 to 2021/22. British Journal of Sports activities Medication. December 6, 2022;57:292–298.
Afonso J, et al. The Hamstrings: Anatomic and Physiologic Variations and Their Potential Relationships With Harm Threat. Frontiers in Physiology. July 7, 2021;12.
Charniga B, Private Communication, 1/3/24.
Li Li and Ruan M. “Nordic Train Ought to Not Be Used for Predictive Modeling of Hamstring Accidents,” Particular Communication. Medication and Science in Sports activities and Train. December 2018;50(12).
Milanese S, et al. “Hamstring accidents and Australian Guidelines soccer: over-reliance on Nordic hamstring workout routines as a safety measure?” Journal of Sports activities Medication. July 23, 2019;10:99–105.
McGill S. “An Method to Ache-Free Coaching for Observe Athletes with Stuart McGill.” SimpliFaster. 1 December 2023.
Ruan M, et al. “The Relationship Between the Contact Power on the Ankle Hook and the Hamstring Muscle Power Through the Nordic Hamstring Train. Frontiers in Physiology. March 9, 2021;12.
Freeman BW, et al. “The results of dash coaching and the Nordic hamstring train on eccentric hamstring power and dash efficiency in adolescent athletes.” Journal of Sports activities Medication and Bodily Health. July 2019;59(7):1119–1125.
Alt T, et al. “What Are We Aiming for in Eccentric Hamstring Coaching: Angle-Particular Management or Supramaximal Stimulus?” Journal of Sport Rehabilitation. June 20, 2023;32(7):782–789.
Pacek A. Private Communication. 12/20/23.
Gagné P. Private Communication. 12/15/23.