WHAT WILL YOU LEARN?
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?
WHO? WHAT? HOW?
Hamstring strains are a common acute sports injury that sports physiotherapists encounter regularly in the clinic.
They are 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)
Hamstring strains are very common in sports that involve high levels of sprinting and agility such as AFL, soccer and athletics (i.e. 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).
Truth 1: Exercises Can Decrease Recurrent Strains!
ANATOMY IS THE KEY!
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.
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.
In this graph, it demonstrates the relationship between bicep femoris fascicle length and Nordic exercise strength.
With a weak/short biceps femoris had a 40% probability of hamstring strain compared to 3% probability with a strong/long biceps femoris.
Truth 2: Eccentric Exercises Are Awesome!
ECCENTRICS ARE PREVENTIVE AND NECESSARY!
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).
Truth 3: Hamstring Strength Is Not Enough
WHAT ELSE IS IMPORTANT?
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:
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
Single Leg Bridge on Step Single Leg Deadlift
Concentric/Eccentric Moderate Length
- Hamstring curls are great for this but also include your bridging based exercises
- We can really work at developing strength and power with these exercises
Seated Hamstring Curl Barbell Hip Thrust
- 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
Eccentric Hamstring Curl on Ball Nordic Curl
- 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
Cable Glute Extension Rear-foot Elevated Split Squat
- This involves a full body movement that incorporates a mixture of trunk rotations, upper body strength and single leg exercises
Cable Wood Chop Drop Jump from Height with Hurdle Jumps
- A gradual running/sprinting program is vital for hamstring rehab and should be progressed over 3-6 weeks (depending on severity of this strain)
Resisted Sprints Agility Work
Photos supplied by Physitrack
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.
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.