Hamstring Rehab – Not just the Nordic Curl

I am surely not teaching you anything new when I tell you that the Nordic curl exercise has often been touted as a gold standard exercise for hamstring injury prevention and strengthening. There is indeed a lot of evidence to support its effectiveness in targeting the short head of the biceps femoris and the semi-tendinosus.

However, we must remember that the hamstrings are a bi-articular muscle, and this bi-articular anatomy means that the hamstrings are often heavily stressed over two joints simultaneously: at the hip and the knee.

There is also some evidence that there may be a neuromuscular component to hamstring strains due to the double innervation of biceps femoris.

But there are other potential contributing factors that are modifiable.  These include quadriceps or glute max imbalance, running posture, lack of hamstring extensibility or adverse neural tension, among others.

While I agree that the Nordic curl is an effective tool, this article will highlight rehab progressions to improve neural tension combined with exercises that generate a more uniform bi-articular activation of the hamstrings.

Failure to address these two important elements may slow rehabilitation and increase the likelihood of reinjury.

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ADVERSE NEURAL TENSION AND HAMSTRING STRAINS

Adverse neural tension can be defined as:

“abnormal physiological and mechanical responses in nervous-system structures when the normal range of movement and stretch capabilities are exceeded”

Given the close proximity of the hamstrings to the sciatic nerve, there is evidence to support that adverse neural tension may result from or be a contributing factor in the etiology of repetitive hamstring strains (1, 2):

-an increase in neural tension may result in pain, decreased neural mobility and decreased extensibility of the hamstrings

-repetitive hamstring strains, through inflammation and scarring, may interfere with normal neural mobility, contribute to adverse neural tension and influence hamstring flexibility

As always, the question is which came first, the chicken or the egg?  Either way, it becomes apparent that including neural mobilizations is an integral part of prevention and rehabilitation of hamstrings strains.

HAMSTRING TIGHTNESS OR NEURAL TENSION?

You might be thinking: How can I tell if my client has hamstring tightness or neural tension? 

Great question!

They can be quite hard to differentiate, especially subjectively from the part of your clients.  But the good news is, if you’re already looking at their hamstring flexibility, you’ll get part of the answer.  

As you perform a passive straight leg raise (PSLR) test for hamstring length, keep one hand on the ASIS.  If they have limited range on the PSLR (less than 80 degrees) and the ASIS moves as you try to bring them through range, that’s likely the hamstring pulling the pelvis posteriorly to get the hip into more flexion.  Hamstring length is probably an issue.  

If they have limited range and the ASIS does not move, neural tension is probably an issue.

If you’re not familiar with the PSLR, here is a video to take you through the test:

I won’t lie, sometimes there is both some lack of hamstring extensibility and some neural tension.  A trick is to dorsiflex the ankle at end range or have them flex the head.  If that makes the tension worse, there is most probably a neural element.

NEURODYNAMIC MOBILIZATIONS: GLIDING AND TENSIONING

Not only are neurodynamic mobilizations great to treat adverse neural tension, but as you progress from neural gliding to neural tensioning exercises, they can just as well serve to improve hamstring flexibility (3, 4).

Gliding exercises

Neural gliding exercises are a great starting point, especially if there is significant adverse neural tension and/or in the case of chronic, repetitive hamstring strains where we suspect there is some scarring and impedance on the neural tissue.

Neural gliding exercises produce a sliding movement of neural tissue by applying tension distally while simultaneously releasing tension proximally and vice versa

For example, simultaneously extending the knee and extending the head, then reversing that order to simultaneously flex the knee and flex the head:

As your client or athlete progresses, you can create more nerve excursion by increasing the range (and therefore also the intensity) of the neural gliding exercise:

Tensioning exercises

The next progression once there is significantly less adverse neural tension, is to go from gliding exercises to tensioning exercises.  These will also help improve and/or maintain hamstring extensibility.

In neural tensioning exercises, you are applying tension both distally and proximally so as to “stretch” the neural tissue

These are more intense, which is why they come later in the progression.

If we take the same example as above, we would simultaneously extend the knee and flex the head, so as to “pull” on both ends of the neural tissue:

DON’T FORGET TO STRENGTHEN

If you know me, you know “rehab is training”.  

Neural mobilizations help to restore the balance between movement of the neural tissue and surrounding tissues, and in this case, specifically the hamstrings.

As you work through the different levels of neural gliding and tensioning exercises, you can match this with your selection of strengthening exercises.  

Your neural mobilizations will give you range of motion to work with, and you want to load these new ranges of motion

The hamstrings can undergo strong elongation in the deceleration portion of the running cycle, where there is a strong eccentric deceleration of combined hip flexion and knee extension.  This is the common mechanism of injury for many hamstring strains.

This means that earlier in the rehab process, you may not be able to overload the muscle via a lengthening exercise, like an RDL, where the torso is moving over the hips and the hamstrings are eccentrically lengthening.

Many of your higher intensity loading exercises may be focused on knee flexion exercises where the muscle is shortening, as tolerance to this is higher earlier on.  This is where your leg curls and Nordic curls come in handy:

As you start to increase the excursion on your gliding exercises, this will match with initiating hip extension exercises.  Because they are performed at longer lengths, hip extension exercises generate a more uniform bi-articular activation and may be beneficial in hamstring injury rehabilitation and prevention of reoccurrence.

You might start with a shorter range of motion exercise like a kickstand (or staggered stance) RDL:

Your final progression would be a full range of motion hip extension exercise such as a single-leg RDL:

I tend to use a supported single-leg RDL when I am focused on overloading, so that balance does not become my limiting factor.  However, somewhere in the program, there will also be true single-leg work given that this is an important element to transfer over to the athletic environment.

THE FINAL TAKE-AWAY

Strength in the continuum of care is always a crucial aspect of rehab programming.  

I would argue that the most important element of rehab is applying strategies that balance protecting the injury will still exposing clients and athletes to load.  Then, using periodization to progressively expose them to the loads (and positions, postures, movements) that were initially offensive so that they regain tolerance.

In the case of hamstring strains, think of matching:

– neural mobilizations in a progression from shorter excursion, longer excursion then tensioning 

-loaded exercises progressing from shortening, short range lengthening then full range lengthening

This is a great progression to improve adverse neural tension, tolerance to stretch, hamstring extensibility and strength through range.

Of course, we haven’t yet touched on speed and timing of contraction further down the rehab continuum, but that will be for another article. ?

References

1. Turl, S. E., & George, K. P. (1998). Adverse neural tension: a factor in repetitive hamstring strain?. The Journal of orthopaedic and sports physical therapy, 27(1), 16–21. 
2. Newsham, Katherine. (2006). The Role of Neural Tension in Minor and Recurrent Hamstring Injury, Part 1: Evaluation. Athletic Therapy Today. 11. 54-56. 10.1123/att.11.4.54.
3. Castellote-Caballero, Y., Valenza, M. C., Puentedura, E. J., Fernández-de-Las-Peñas, C., & Alburquerque-Sendín, F. (2014). Immediate Effects of Neurodynamic Sliding versus Muscle Stretching on Hamstring Flexibility in Subjects with Short Hamstring Syndrome. Journal of sports medicine (Hindawi Publishing Corporation), 2014, 127471. 
4. RAGIA M. KAMEL, Ph.D., S., & SALEH, Ph.D., M. (2021). Immediate Effect of Neurodynamic Tensioner Versus Proprioceptive Neuromuscular Facilitation Stretch on Subjects with Short Hamstring Syndrome. The Medical Journal of Cairo University, 89(June), 627-634.

Mai-Linh Dovan M.SC., CAT(C)
Certified Athletic Therapist
Founder of Rehab-U