The Nordic Hamstring Debate: What The Evidence Actually Says
This post explores the research underpinning the Nordic hamstring exercise and how it does (and does not) support injury prevention.
The Nordic hamstring exercise is one of those rare exercises that seems to sit at the centre of both strong evidence and strong opinion.
For some practitioners, it is a staple. A simple, low-equipment, eccentric hamstring exercise with a compelling injury prevention evidence base. For others, there are concerns about its compliance and the simplification that it can solve a complex injury problem on its own. As usual, I think the most useful answer sits somewhere in the middle.
This article is part of my Athlete Testing Series, in collaboration with VALD. Given VALD make the NordBord, it is important to be upfront that they have an interest in Nordic testing and training. However, the aim here is not to argue that Nordics are the only answer. It is to look at what the evidence actually supports, why the debate exists, and how practitioners might think about using Nordics in the real world.
Why The Nordic Hamstring Exercise Became So Popular
The Nordic hamstring exercise is not a new idea. In fact, some form of the movement appears in physical training texts dating back to the 19th century.
What has changed over the last two decades is the strength of the research base, and the ability to quantify the exercise through the NordBord.
At a simple level, the Nordic is appealing because it is practical. It requires relatively little equipment, it can be implemented in team environments, and it gives practitioners a way to load the hamstrings eccentrically through a knee-flexion dominant task. That matters because many hamstring injuries occur during high-speed running, when the hamstrings must tolerate high forces while lengthening.
There is also evidence in support of this exercise and injury risk mitigation. In the Bourne et al. (2018) Sports Medicine review, the authors note that a number of prospective studies have established that eccentric knee flexor strengthening can reduce hamstring strain injury risk (reported 50–70% reductions in hamstring injuries in sub-elite soccer), with the protective role evident only when compliance is adequate.
They also point out that the Nordic hamstring exercise has a uniquely strong evidence base for preventing hamstring strain injury, despite not closely matching the load, range of motion and velocity demands often proposed as essential for sprint-related injury prevention exercises.
That is one of the reasons this topic is so interesting. The Nordic is not sprinting, and it does not pretend to be. Yet it appears to influence some of the physical qualities we care about.
[M]any hamstring injuries occur during high-speed running, when the hamstrings must tolerate high forces while lengthening.
What Adaptations Are We Actually Chasing?
The case for Nordics is that it can influence physical qualities, and thereby risk factors, that are relevant to hamstring strain injury.
Nordics can improve eccentric knee flexor strength, increase biceps femoris long head fascicle length, and may shift the angle of peak knee flexor torque towards longer muscle lengths. In the Bourne review, these adaptations are discussed as likely contributors to the injury-protective effect of eccentric knee flexor strengthening, although the authors are careful not to reduce the mechanism to strength alone.
That caution is important: stating “stronger hamstrings do not get injured” is oversimplifying the message.
The figure below originally from Timmins et al. (2015), as discussed in the YouTube video, is a useful example. It plots pre-season biceps femoris long head fascicle length (y axis) and eccentric knee flexor (Nordic) strength (x axis) values for professional soccer players who did (red dots) and did not (green dots) suffer a hamstring strain injury in the subsequent competitive season.
The higher-risk athletes tended to sit in the lower-strength, shorter-fascicle region, which supports the relevance of those measures. Players with short biceps femoris long head fascicles (< 10.56 cm) and low eccentric strength (< 337 N) were 4.1 and 4.4 times, respectively, more likely to suffer a future hamstring strain injury than those with longer fascicles or higher levels of strength.
But the picture is not perfectly clean. Some athletes with stronger scores and longer fascicles still became injured, while some athletes with poorer profiles did not.
That is not a reason to dismiss the measures. It is a reason to interpret them properly.
A low Nordic score or short fascicle length may give us useful information about an athlete’s profile. A high Nordic score does not give us permission to ignore previous injury, sprint exposure, fatigue, running mechanics, training load, lumbopelvic control, or any of the other interacting factors that influence hamstring injury risk.
As is often the case in sports science research, it is important to point out that much of the Nordic hamstring literature has been conducted in male athletes, particularly in male football codes. That does not mean the principles are irrelevant to women’s sport, but it does mean we should be careful about making assumptions with other populations. This is why it's so important and exciting to see an increase in women's data available through projects such as the FIFA Female Health Project and VALD's recent Normative Data Report in the Women's Super League (WSL).
Why The Debate Exists
The debate around Nordics is partly evidence-based and partly implementation-based.
The evidence-based critique usually starts with specificity. The Nordic hamstring exercise is a knee-flexion dominant task performed in a constrained position. Sprinting, by contrast, requires rapid coordination across the hip, knee and ankle, with high-speed lengthening, force production, trunk and pelvis control, and very precise timing demands.
That distinction is valid. Nordics are not sprinting, and practitioners should not behave as if they are.
This is exactly where the debate can become, in my view, unnecessarily polarised. Saying “Nordics are not sprinting” is true, but it does not make the exercise useless. A squat is not jumping. A calf raise is not sprinting. An isometric groin squeeze is not changing direction. Yet all of these exercises can still provide useful information and create useful adaptations when applied in the right context.
The question is not whether the Nordic perfectly replicates the sporting action. It does not. The better question is whether it targets a relevant capacity that the athlete needs, and whether it is being used alongside the other exposures required to prepare the athlete for sport.
Nordics Are One Hamstring Exercise, Not The Hamstring Exercise
One of the most useful parts of the Bourne Sports Medicine review is the discussion around exercise selection, and how hamstring activation patterns and training adaptations differ between exercises.
In general, hip-extension oriented movements such as stiff-leg deadlifts appear to show relatively greater biceps femoris long head, while knee-flexion oriented movements such as Nordics and leg curls appear to show relatively greater semitendinosus activation (see below).
That finding challenges the idea that any one exercise can cover the entire hamstring group or the entire injury problem. If different exercises create different stimuli, then exercise selection should be driven by the adaptation we are trying to achieve.
In practice, Nordics may sit alongside hip-dominant strength work, progressive high-speed running and sprint exposure, isometrics, calf and hip assessment where relevant, and broader trunk and pelvis work. The exact blend depends on the athlete, the sport, the phase of the season, and the problem you are trying to solve.
If different exercises create different stimuli, then exercise selection should be driven by the adaptation we are trying to achieve.
This is also where practitioner judgement matters. A Nordic may be a good option for one athlete and a poor option for another at a particular moment. The exercise itself is not the programme.
Where NordBord Testing Fits
One reason the Nordic conversation evolved is that the exercise became measurable via the NordBord. Counting repetitions alone tells us what was prescribed, but it does not tell us what was produced.
Two athletes might complete three sets of Nordics and create very different force outputs, asymmetries, movement strategies and training stimuli. That is where the NordBord can add value. It allows practitioners to quantify eccentric knee flexor strength in real time, particularly now with Training Mode, monitor left-right differences, assess repetition quality alongside what we see with our eyes, and track change over time.
As with any testing tool, though, the score needs context. It gives us one lens on eccentric knee flexor capacity, but it is not a complete hamstring risk profile. If an athlete has a high NordBord output but poor sprint exposure, altered running mechanics, unresolved symptoms, poor tolerance to high-speed running or deficits elsewhere in the posterior chain, I would not be reassured by the score alone.
For more detailed guidance on NordBord protocol, testing setup and analysis, see the video below from my VALD Athlete Testing Series.
Implementing the Nordic Hamstring Exercise
The bigger practical question is not just whether Nordics can work, but whether they are introduced in a way that athletes tolerate and actually continue to do.
That sounds obvious, but it is a recurring problem in injury prevention. An intervention can be well-supported in the literature, but if it causes too much soreness, competes poorly with the rest of the training week, or never quite gets coach and athlete buy-in, the real-world effect is going to be limited.
That is why I would be cautious about dropping high volumes of Nordics into a programme without considering the athlete’s training history, current load and previous exposure to eccentric hamstring work. A gradually progressed approach is far more likely to be sustained. The VALD Practitioner Guide to Hamstrings outlines an initial progressive period and notes that, once this has been established, preventative benefits may be maintained with as little as two sets of four repetitions once per week.
In practice, I would not ask simply whether Nordics work or do not work. I would ask what adaptation I am chasing, whether the athlete tolerates the exercise, how I am progressing or regressing it, what the output looks like, and what other gaps still need to be addressed.
For some athletes, Nordics may be a useful way to build or maintain eccentric knee flexor capacity. For others, they may be too provocative, poorly performed, or less relevant than another option at that moment. In rehabilitation, they might begin as an assisted variation, an isometric hold, a partial range exposure, or a full eccentric task depending on the athlete’s symptoms, capacity and confidence.
They also need to sit alongside sprint exposure. If the athlete’s sport requires sprinting, eventually the athlete needs to sprint. Nordics may help develop useful capacity, but they do not replace preparation for the task itself.
Final Thoughts
The Nordic hamstring exercise has one of the strongest evidence bases we have in hamstring injury prevention. That should not be dismissed just because the exercise is not perfectly sport-specific.
At the same time, Nordics are not a magic bullet. They are not sprinting, they are not a complete hamstring programme, and they are not a standalone risk prediction tool.
For me, the debate should not be whether Nordics are good or bad. The better question is how, when, why and for whom we use them.
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