1 in 3 Hamstring strains will reoccur, usually in the first 1-2 weeks after returning to sport. It has been speculated that there are potentially a few reasons for this. Are athletes returning too early to sport, are we missing a piece of the puzzle in rehab, or are there some risk factors that are stacked against us anyway?

To date, we don’t have an exact answer to this question, as most injuries are multi-factorial, it can go back to the correlation vs causation argument e.g. If you smoke, it doesn’t mean you definitely WILL get lung cancer, but you are more likely to get lung cancer. The figure below shows the consideration required to prevent injuries in a professional sports team – with a little bit of luck coming into the equation!

So how should we go about reducing these injuries if there are all these potential causes?

1. Starting well – is it actually a hamstring injury?

Pain at the back of the thigh can vary in cause and that is an important factor to note. We can’t manage an injury to its potential if we don’t know where the origin of the pain is coming from.

Some of the causes of pain at the back of the thigh include:

- Hamstring Strains – muscle tears and ruptures

- Neural Hamstring pain

- Referred Pain from the lower back or glutes (deep gluteal syndrome)

- Quadratus Femoris pain

- Tendon pain (tendinopathy)

- Delayed onset muscle soreness (DOMS)

- Adductor Magnus Muscle strain

A correct diagnosis is a great place to start. In most cases, this can be done in the clinic by a physiotherapist or sports doctor without imaging, however, there are some circumstances where medical imaging may be warranted. Imaging is justified if treatment will differ depending on the diagnosis or if required to rule out another diagnosis.

A sharp pain on a specific point at the back of the thigh whilst performing an activity such as running (usually sprinting), kicking or a rapid change of direction movement should create some suspicion of a hamstring strain/tear.

2. Age

Over the age of 23, hamstring injuries are more common. We call this a non-modifiable risk factor as it is something we can’t change, because we can’t turn back time! This means we just have to be more diligent with preventing and managing hamstring injuries after this age, particularly if there is a past history of hamstring injuries.

3. Previous history of hamstring injury

Unfortunately, once you have had a hamstring injury, you are more likely to suffer another one. This is likely to do with scar tissue (what replaces the injured muscle tissue) being weaker than the original muscle tissue. Like age, this is another non-modifiable risk factor.

4. Tendon involvement

The tendons in the hamstrings are very long, and in some places they overlap the muscle (see image below of the back of the thigh). The significance of tendon involvement is that it receives less blood flow than muscle, leading to a slower healing process. Tendon involvement can significantly slow the athletes return to play or cause a re-tear of the hamstring if certain activities are commenced too soon. Hence it is important to return to sport confident that all the boxes have been ticked by your physio.

5. Exposure to High Speed Running

As with strengthening your muscles in the gym via resistance exercise, if you perform high speed running, this will improve the ability of the muscle to withstand the forces required for running. As sprinting is one of the most common ways to injure your hamstring, it should be approached in a calculated manner (not too many) but not avoided completely.

The exposure to high speed running on a regular basis (>90% efforts) was successful for Tom Trbojevic’s return in the 2021 NRL season after a series of hamstring injuries.

6. Eccentric Exercises

Eccentric exercises are where the muscle is working as it lengthens, compared to a concentric contraction, where the muscle is working as it shortens e.g. lifting the weight up to your shoulder during a bicep curl). When you are lowering the weight back down to your waist/side (starting position), that is the eccentric phase.

The “leap” phase of running in the photo above, where the foot is advancing forward before impact is where the hamstring works most with sprinting. It works to decelerate the foot so that it doesn’t shoot out too far in front of you. This is where the hamstring is at its weakest and where we need to work on getting it stronger, it is an eccentric contraction as the hamstring is working but stretching at the same time.

Much like exposing your hamstrings to high-speed running to make the muscles more adaptable and resilient, we need to strengthen it in a certain way to get the best results.

Exercises like the Nordic are popular in hamstring injury prevention, reducing injury rate by around 50%. https://www.youtube.com/watch?v=NfBGKhjedD8 It is quite a challenging exercise, and can lead to DOMs (delayed onset muscle soreness for a few days afterwards. It is advised that you perform this exercise with good supervision at least initially and a proper warm-up or build up beforehand. Modifications are often required due to its difficulty.

It works the hamstrings eccentrically in the range of motion required to reduce the chance of muscle failure i.e. a muscle tear.

7. Returning to sport when the hamstring stops being painful (too early!)

The absence of pain when walking or jogging is not enough when it comes to returning to sport. In fact, pain free jogging and walking is generally something achieved quite early in the rehab process for a hamstring injury, it is high-speed running and kicking which needs to be built back in.

It is heavily encouraged to have a tickbox approach to return to play with set criteria, this should involve at minimum the following steps:

- Successful completion of high-speed running sessions

- Successful completion of a training week at full intensity

A physiotherapist will also use some of the following criteria to gauge readiness to return to training and sport:

- Full pain free strength, comparable to the other side

- No pain with stretching the muscle

- Completion of agility, hopping and running tests

- Other hamstring specific tests

- No pain when pushing (palpation) over the area of the tear

In Summary

Whilst hamstring muscle injuries are common and there are some risk factors that may be out of our hands (such as age and previous injury), it is important to have appropriate guidance with these injuries to rehabilitate them thoroughly and leave no stone unturned. Returning too early without completing adequate rehabilitation is something that is in our control.

If you need assistance or guidance with a hamstring injury, or any other muscle tear, feel free to contact one of our Sports Physiotherapists.

Written by Matthew Anthis – Titled Sports and Exercise Physiotherapist and Hamstring Researcher