3 Truths Behind Hamstring Strains




1. Current evidence related to the mechanism behind a hamstring strain, the importance of particular exercises that can decrease the risk of hamstring strains


2. Exercise programming for the individual returning from hamstring injury.


3. How a hamstring rehab program can be a great hamstring strain prevention program!


What Is A Hamstring Strain?



Hamstring strains, normally classified as proximal or distal strains, mostly involve eccentric muscle action and generally occur in either a sprinting-type activity (e.g. leg deceleration in terminal swing) or stretching type activity (i.e. picking up a ball) (Tsaklis et al 2015). 


So very common in sports that involve high levels of sprinting and agility such as AFL, soccer and sprinters. 


Though a majority of function may be restored when an individual returns to play, eccentric hamstring strength has shown to be inadequate and a contributing factor to the high hamstring strain recurrence rates (Askling, Saartok & Thorstensson 2006).


Hamstring muscle group


Truth 1: Exercises Can Decrease Recurrent Strains!



Fascicle length


A muscle fascicle is a bundle of skeletal muscle which increases in length after resistance training, usually eccentric training. There is a significant correlation between short (measured by fascicle length) and weak biceps femoris with hamstring injuries.



Muscle fascicle


Prior hamstring injury and biceps femoris fascicle length is shown to have a strong relationship with each other (Alonso-Fernandez, Docampo-Blanco & Martinez-Fernandez 2017). With no previous hamstring injury, a relationship exists between shorter fascicle length and increased probability of hamstring injury (9cm associated with 38% likelihood, respectively).


With previous hamstring injury, the probability is significantly greater with a shortened fascicle length (9cm associated with 65% likelihood, respectively) (Opar 2016). Though the non-modifiable risk factor of previous hamstring injury is set, we are able to use exercise to modulate the modifiable risk factor of fascicle length.


Below is a graph demonstrating the relationship between bicep femoris fascicle length and Nordic strength. With a weak/short biceps femoris had a 40% probability of hamstring strain compared to 3% probability with a strong/long biceps femoris.


Quadrant of doom (Courtesy of In:Motion Technologies)


Truth 2: Eccentric Exercises Are Awesome!



Contraction type


Muscle contraction types have an effect on fascicle length adaptation. After a 6-week concentric or eccentric only hamstring strengthening program, both eccentric and concentric exercise adaptations occur within 2-weeks of an exercise program. With concentric training, there is a change in fascicle length by -13.3% at 6 weeks.


The shortened fascicle adaptation is maintained after the strength training stimulus is removed (-12.2% at 10-weeks). Moreover, eccentric training has a similar but opposite effect on fascicle length, fascicles lengthen (14.1% at 6-weeks and 0.8% at 10-weeks) yet all adaptations are removed once the eccentric training stimulus is removed.


This highlights the importance of continuing eccentric hamstring exercise application as a preventative measure of recurrent hamstring strains (Timmins et al 2016).


Contraction types


Truth 3: Hamstring Strength Is Not Enough





During detraining periods, as previously discussed, once the eccentric training stimulus is removed, fascicle length adaptations are lost. However, though there is a loss in fascicle length, only small losses in strength adaptations associated with eccentric training are observed (Timmins et al 2016).


This is an interesting finding, as it may demonstrate why so many athletes will return to sport with adequate strength, but may reinjure in the future. It may be related to either the lack of eccentric strength work completed during their rehab or the cessation of eccentric exercises once they return to play.


What can we do about it?



The goals of a well-rounded hamstring rehab program is to cover these areas:


1. Concentric/Eccentric Long Length

  • Hip extension based exercises that keep you locked at the knee and bending forward at the hip
  • This is really important for footy players as the requirements of the game involve bending down and picking the ball from the ground


2. Concentric/Eccentric Moderate Length

  • These are your bridging based exercises
  • We can really work at developing strength and power with these exercises


3. Eccentric Only

  • The Nordic curl (as discussed above) are the perfect example of and eccentric only exercises
  • These are quite difficult, so there are many variations that allow someone to slowly progress to a full Nordic exercise. As stated, this process can take weeks to months, depending on the individual’s hamstring capacity


4. Gluteals

  • We need the gluteals to work with the hamstrings
  • There are many exercises that can be done for glute strength. The key is to make it relevant to the sport and have a focus on control


5. Whole/Neuromuscular

  • This involves a full body movement that incorporates a mixture of trunk rotations, upper body strength and single leg exercises


6. Running Mechanics

  • A gradual running/sprinting program is vital for hamstring rehab and should be progressed over 3-6 weeks (depending on severity of this strain)


Now, if you have not covered all these areas in your previous hamstring rehab programming…it is likely that you have re-injured your hamstring at some point OR at increased risk of straining your hamstring.


Final Thoughts


What we see in the clinic quite often are athletes returning to their given sport too early after they have strained their hamstring. They usually think:


“My pain is gone, so it must be healed”


“I can lift heavy deadlifts, so my hamstring should be strong enough”


“It’s just a little sore, it should be right”


We need to ensure that we tick all the boxes before a safe return to sport and decrease the risk of re-injuring your hamstring.


If you would like me to call you to discuss your previous or current hamstring program, whether you are on the right track for preventing a future hamstring & how we may be able to offer you a solution, then please fill in the contact form below and leave your best contact number. 


If you’re sick of constantly “doing your hammy” and just want to get back to it without any worry… follow the book online link in the top right corner & we hope to help you soon!




David Bruzzese

APA Musculoskeletal Physiotherapist & Accredited Exercise Physiologist




Alonso-Fernandez, D, Docampo-Blanco, P & Martinez-Fernandez, J 2017, ‘Changes in muscle architecture of biceps femoris induced by eccentric strength training with Nordic hamstring exercise’, Scandinavian Journal of Medicine & Science in Sports, pp. 1-7.

Askling, C, Saartok, T & Thorstensson, A 2006, ‘Type of acute hamstring strain affects flexibility, strength, and time to return to pre-injury level’, British Journal of Sports Medicine, vol. 40, pp. 40-44.

Timmins, RG, Ruddy, JD, Presland, J, Maniar, N, Shield, AJ, Williams, MD & Opar, DA 2016, ‘Architectural changes of the biceps femoris long head after concentric or eccentric training. Medicine & Science in Sports & Exercise, vol. 48, no. 3, pp. 499-508.

Tsaklis, P, Malliaropoulos, N, Mendiguchia, J, Korakakis, V, Tsapralis, K, Pyne, D & Malliaras, P 2015, ‘Muscle and intensity based hamstring exercise classification in elite female track and field athletes: implications for exercise selection during rehabilitation’, Journal of Sports Medicine, vol. 6, pp. 209-217.


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