Introduction
The Nordic hamstring curl (NHC) – also known as just ‘Nordics’ – are becoming increasingly popular among people wanting to run faster, jump higher and prevent injuries. But are Nordics really all that they are made out to be?
Nordics may be helpful long term for sprint and general athletic performance, but they are by no means the best (or even a good) exercise for targeting sprint performance. Nordics may also not have the purported injury-prevention effects that most people claim. Nonetheless, even if Nordics are widely ‘overhyped’, it can still be beneficial to implement them into one’s training occasionally.
In this article we are going to dive into the theory and science of Nordics as they relate to athletic performance and injury prevention. Just before that, if you really want to improve your acceleration speed, then check out this article where I’m offering a free technique critique + suggesting improvements.
Now back to Nordics. Let’s go.
Update: I’ve since made a video on this topic that you might be interested in checking out
What are Nordics?
If you’re reading this article, then you likely already know what the NHC is. For the unfamiliar, the NHC, as the name suggests, is a hamstring exercise.
It is a bodyweight exercise that is performed by securing your feet under a heavy object (for example, under a barbell with a lot of weight on it) with your feet pointing down.
You then slowly lower your body into the ground via extension at the knee joint. The movement can be loaded, however for most people using only their bodyweight is already difficult enough.
Here’s a video demonstrating the movement.
In the above video we can see the ‘kneesovertoesguy’ demonstrating the NHC. I would attribute much of the rise in popularity of the NHC to the kneesovertoesguy.
He claims in the video that the ability to do the NHC is the greatest common denominator between ‘horizontal athletes’ (think sprinters, long and triple jumpers). He also mentions the study that has shown that the NHC can prevent hamstring injuries by as much as 50%.
I’ve also heard another argument in favour of the NHC which goes like this: during sprinting, when the leg touches the ground, the hamstring is in a lengthened position. Nordics train the hamstrings to be strong in a lengthened position. Therefore, Nordics help you get faster.
Here’s my counter argument – sprinting is extremely specific. It’s always difficult to predict how a certain exercise will transfer to sprinting, simply because sprinting really is like nothing else.
While you are sprinting, your whole body must coordinate in a highly specific way, with your muscles shortening and lengthening at a rapid rate and your feet contacting the ground for ~1/10th of a second.
Sprinting is specific. It’s very difficult to predict whether an exercise in the weight room will transfer over to the unique nature of sprinting.
Any exercise you do in the gym will most definitely look completely different from sprinting. The body’s movement during sprinting is very different than during a Nordic. Also, the speed at which each movement is performed is also opposed (one possibly being the fastest movement the human body is capable of, the other occurring over several seconds).
So, saying that your hamstrings need to be strong in a lengthened position and therefore that NHC = sprint gains won’t cut it.
Instead, we need to look to people who have actually done the experiments. So, let’s get into the studies.
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Do Nordics Make You Faster?
Nordics may improve sprint performance over a small distance compared to a control group.
The reason I say ‘may’ is because there is conflicting evidence in the literature.
For example, let’s consider a study titled “Effects of the Nordic Hamstring exercise on sprint capacity in male football players: a randomized controlled trial”.
This study found that the best 10m sprint time out of a repeated-sprint ability test was higher in athletes that had undergone strength training involving the NHC.
This study looked at amateur soccer/football players and assessed their progress using a repeated-sprint ability test. This means that the athletes did not get much rest in between reps or sets.
Sure, if you’re a soccer/football player, then you ought to aim to improve this quality. However, if you’re a sprinter, then your race only involves one rep. The study concluded that the NHC showed small to medium improvements in sprint performance after 10 weeks of training.
For whatever reason, a lot of the studies looking at the relation between the NHC and sprint performance was done using soccer players. Hence, be wary that the results found in these studies may not generalize to wider populations.
Now let’s consider another study called “Sprint versus isolated eccentric training: Comparative effects on hamstring architecture and performance in soccer players”.
This study compared the effects of sprinting vs Nordics vs the control group on sprint performance (as well as hamstring muscle ‘architecture’) over a 6-week period in soccer/football players.
The study found that only the sprint training group was able to simultaneously improve their sprint performance as well as increase their biceps femoris long head fascicle length (which is believed to help prevent hamstring injury). Only trivial to small negative changes in sprint performance and sprint mechanics were observed in the Nordic and the control group.
In other words, only sprinting itself was able to improve sprint performance whereas Nordics only resulted in trivial positive changes to sprint performance at best and negative changes at worst. This result agrees with the statement I made previously about sprinting being highly specific.
Now let’s consider a meta study (in other words, a study that reviews and summarizes the results of many other studies). The title of the study is “The effects of the Nordic hamstring exercise on sprint performance and eccentric knee flexor strength: A systematic review and meta-analysis of intervention studies among team sport players”.
A meta study that considered 17 distinct studies on the NHC and its effect on sprint performance
After looking through 17 distinct studies, this meta-analysis found that Nordics had a positive effect on sprint performance over 10m. However, it was also found that Nordics did not make a significant difference when looking at 5m and 20m sprint times.
I found this quite strange. You would think – with all else being equal – that an improvement in 10m sprint time would result in an improvement in 20m sprint time. I therefore have my suspicions about the studies considered in this meta analysis, and perhaps will look further into them at another time.
Methodological differences could potentially be the culprit for the conflicting results throughout the literature. For example, whether the exercise was performed immediately before sprinting or as a more general strength program at a separate time.
It is possible that performing 1 or 2 Nordics immediately prior to a sprint may have a potentiation effect, thereby increasing sprint performance in the short term. However, it is possible that Nordics in the long term may not have a positive effect on sprint performance.
Nonetheless, if we take this study at face value, it does appear that Nordics might have a small positive effect on 10m sprint speed when incorporated into a long-term training program (10 weeks+).
Does this mean that we should be doing Nordics if we want to get faster? Not necessarily (I’ll get back to this part later)
Nordics – Elite Sprinters vs non-Elite
Let’s now tackle the idea that kneesovertoesguy (and many more) have espoused: the ability to do Nordics is the key to being really fast.
I’d consider myself to be quite good at Nordics. I can go ‘nose to ground’ and up again without using my hands. I can also do the same whilst holding a 10kg (22lb) plate to my chest. I’d also consider myself to be quite fast relative to the general population. However, I’m by no means close to being an elite sprinter.
Now let’s look at this video of current 200m Olympic gold medallist Andre De Grasse struggling to complete the full range of motion whilst doing a ‘Razor Curl’ – an exercise that is extremely similar to a Nordic hamstring curl.
Skip to 7:25 in the video to see De Grasse doing the Razor Curl exercise
I’m fairly confident that I’d be able to outperform De Grasse when it comes to Nordics or Razor Curls. Nonetheless he would wipe the floor with me if it came to anything sprint related.
I’m sure you see the point here. While I’m willing to bet there is some correlation between eccentric hamstring exercises like Nordics and sprint performance, it doesn’t appear to be the ‘magic ability’ that is the key to being fast.
Do Nordics Prevent Injury?
Another claim to fame is that Nordics help prevent hamstring injuries by up to 50%. The study that this claim comes from is titled “Including the Nordic hamstring exercise in injury prevention programmes halves the rate of hamstring injuries: a systematic review and meta-analysis of 8459 athletes”.
Nordics are typically thought to be one of the best hamstring ‘prehab’ exercises, but is that really the case?
This study was also a meta study. However, a recent study from late 2021 titled “Why methods matter in a meta-analysis: a reappraisal showed inconclusive injury preventive effect of Nordic hamstring exercise” has argued that this previous meta-analysis used inappropriate methodology to arrive at their conclusion of injury reduction by up to 50%.
Furthermore, this study argues that if more appropriate methodologies are used, then the evidence underpinning the protective effect of the Nordic hamstring exercise so far remains inconclusive.
In other words, due to potential methodological flaws in the now famous “Nordics decrease injuries by up to 50%” study, these results cannot be replicated. In reality, the injury-prevention abilities of the NHC are unclear.
Advantages and Disadvantages of Nordics
We have already considered a lot of information relating to the Nordic hamstring curl. Before we consider all of it as a whole, let’s finally consider some other relevant points.
Nordics may help improve acceleration mechanics
Previously I made an Instagram post describing how Nordics may help improve your acceleration mechanics.
In short, by increasing your eccentric hamstring strength, you prevent your leg from ‘opening up’ around the knee join when you bring your leg forward during acceleration.
This therefore allows you to strike backwards under your center of mass during acceleration therefore preventing overstriding (for more information on acceleration mechanics, the importance of striking under your centre of mass and overstriding – check out this article here).
For a clear visual explanation of this idea check out the linked Instagram post where I’ve included some pictures to help explain.
However, sometimes this is a form issue rather than a strength issue. Therefore, doing some resisted sprinting (check out my article on resisted sprinting for more information) as well as implementing some appropriate cues may solve the issue.
In this case, your body is already strong enough and you just need to teach it to move correctly. Therefore, Nordics would not help.
Nordics induce hypertrophy of the hamstring muscles
In another article where I considered the most important muscles for sprinting, I looked at a study that compared the muscle volume of elite and sub-elite sprinters. One of the muscles groups that varied significantly between elite and sub elite sprinters were the hamstring muscles.
In terms of muscle volume, one of the biggest differences between elite and sub-elite sprinters are the hamstrings
Hence, hypertrophy of the hamstring muscles over time may lead to increased sprint performance. Moreover, eccentric exercises (such as Nordics) have been shown to be excellent at inducing hypertrophy.
Therefore, Nordics may be able to increase sprint performance through hypertrophy of the hamstring muscles.
Nordics require large amounts of recovery time
However, if you are performing high volumes of Nordics (for instance, a 5×5 session), then it takes quite a long time to recover. This is quite a significant problem.
For instance, if you have track/sprint training multiple times a week, or maybe you play a team sport with weekly training and games, then it can be hard to find time for Nordics.
You especially do not want to be doing something like a 5×5 Nordic session followed by a high intensity sprint session the next day (unless you want to injure yourself). Personally, I know that I need at least one day of recovery after I do a high volume of Nordics (although more often than not I’ll need two days recovery).
Remember, just because an exercise might make you faster, doesn’t mean we should immediately assume we should be doing it. We only have a limited volume of exercise we can perform in a given time. We have to be smart with which ones we pick.
Nordics might help us slightly improve our sprint performance down the line. However, if we have to invest several days of the week to fully recover from them, then that’s not a good return on investment.
Should you be doing Nordics?
Alright, so we just covered a lot of information, but should we be doing Nordics if we want to get faster? Let’s first look at the literature side of things.
People love to cite one piece of literature and say “See, Nordics definitely do/do not improve speed”. Let’s not take such a dogmatic approach. Every study has it biases and flaws (only using a sub-population of athletes, only using a small number of athletes etc…) and new studies continue to come out all the time.
Sure, on topics with repeated results being observed over the years and with a large consensus amongst the experts, we might be more confident in our conclusions. However, this doesn’t appear to be the case with Nordics and their relation to speed.
Nonetheless, it does seem that performing Nordics may result in small increases in sprint performance over small distances (10m).
Also, Nordics may help improve acceleration mechanics and induce hypertrophy of the hamstring muscles which have been shown to be bigger in elite sprinters.
That being said, recovering from Nordics can take significant time and the purported injury-prevention effects of Nordics may not be as clear as previously stated.
However, my biggest problem with the whole ‘Nordics for speed’ idea is that you shouldn’t even be worrying about Nordics if you aren’t already sprinting. That’s because sprinting is both the best way to improve your sprint performance, as well as prevent injuries.
If you want to get faster, sprinting comes first. Only then can you think about accessory exercises to implement.
So, the answer I would give to ‘Should I do Nordics to get faster’ would be probably not.
If you are already sprinting on a regular basis and find that you personally recover from Nordics quickly enough that you can fit them in to your training routine – then go ahead. Doing so might help you improve over short distances and could potentially lead to greater hamstring muscle volume down the line. However, if you’re not already regularly sprinting, then start there first.
Conclusion
Are Nordics necessary to get faster? Absolutely not. Should you be doing Nordics if you want to get faster? Probably not. That is because even though the literature shows that Nordics might help athletes make small improvements over 10m, recovering from Nordics usually takes a substantial amount of time. Moreover, recently the injury-preventing abilities of Nordics has been called into question.
However, what is not in question and will have definite results is sprinting itself, which makes you both faster and reduces the risk of injury.
That being said, if you already sprint on a regular basis, find that you recover from Nordics relatively quickly, and are looking for some additional exercises to incorporate in the gym, then Nordics may be appropriate for you. Just don’t believe that they are the ‘magical speed exercise’. They are simply an optional accessory to the real magical speed exercise – sprinting itself.
References
1) Ishøi, Lasse, et al. “Effects of the Nordic Hamstring exercise on sprint capacity in male football players: a randomized controlled trial.” Journal of sports sciences 36.14 (2018): 1663-1672.
2) Mendiguchia, Jurdan, et al. “Sprint versus isolated eccentric training: Comparative effects on hamstring architecture and performance in soccer players.” PLoS One 15.2 (2020): e0228283.
3) Bautista, Iker J., et al. “The effects of the Nordic hamstring exercise on sprint performance and eccentric knee flexor strength: A systematic review and meta-analysis of intervention studies among team sport players.” Journal of Science and Medicine in Sport 24.9 (2021): 931-938.
4) Van Dyk, Nicol, Fearghal P. Behan, and Rod Whiteley. “Including the Nordic hamstring exercise in injury prevention programmes halves the rate of hamstring injuries: a systematic review and meta-analysis of 8459 athletes.” British journal of sports medicine 53.21 (2019): 1362-1370.
5) Impellizzeri, Franco M., Alan McCall, and Maarten van Smeden. “Why methods matter in a meta-analysis: a reappraisal showed inconclusive injury preventive effect of Nordic hamstring exercise.” Journal of Clinical Epidemiology 140 (2021): 111-124.
