As we are starting to up our running in preparation for marathon training we start to notice a pain located in our inner shin. We continue the run and it eases off slightly. We go out again the next day and it develops further into a sharp pain causing us to halt our run and disrupt our already busy training schedule. The dreaded medial tibial stress syndrome, more commonly referred to as ‘shin splints’. Now what?!
This blog post will look to identify what shin splints actually is, when to seek help and how best it should be treated to ensure you are still able to keep on with your marathon training.
What is Medial Tibial stress Syndrome (MTSS)?
Exercise related lower leg pain is common within the running community and MTSS is one of the most common presentations especially amongst novice runners. MTSS is pain on the inner aspect of the shin that is exacerbated by loading activities (ie. Running, jumping/landing etc). There are a couple of different hypotheses as to what causes MTSS; Bone overload and traction.
Loading can affect the bones in different ways. For example, if it is not loaded enough then it can become weaker and if it is optimally loaded then it becomes stronger. However, bone overload occurs when the load applied surpasses the threshold capacity resulting in microdamage and pain.
It was initially thought that the pain was as a result of the densely innervated periosteum (outer layer of bone) however it is now thought that sensory nerve fibres also innervate the mineralised bone and bone marrow and that these sensory fibres can be stimulated by mechanical distortion.
The traction theory on the other hand suggests that it is the repeated traction on the periosteum by fibres of muscles/structures attached to the length of the medial tibia (flexor digitorum longus, soleus and deep crural fascia) that may be responsible for MTSS. Unfortunately the pathophysiology is still up for debate.
So how would I develop MTSS?
The most common cause for a stress response is overload, whereby the load placed upon the bone outweighs its capacity to tolerate it. This usually occurs through training errors. By doing too much too soon and not allowing adequate time for healing and remodelling of the bone to take place. So for example if our training suddenly increases in frequency or intensity this can result in overload and pain. In novice runners it may take a little longer to adapt to the load and therefore a gradual approach/increase in training is always advisable. Changes in lifestyle factors can also have an impact on our bone health. For example changes in sleep pattern and diet.
Other factors that are linked to developing MTSS can include a higher navicular drop. This is used as an indicator of increased foot pronation. It is thought that increased pronation can potentially cause added traction from the muscles during repeated loaded tasks.
Athletes with MTSS have also been shown to have endurance deficits of the ankle plantar flexors (ie going into a calf raise). The calf complex is thought to produce up to 60% of propulsion force during running and the soleus has been shown to be very important absorbing load during running. If these are weaker then it may result in excessive load being transmitted through the tibial cortex producing a stress response.
Unfortunately females are thought to be three times more likely to develop MTSS. In addition, an impaired ability to maintain dynamic joint stability is a significant contributor to the development of MTSS in females. It is therefore important that we assess and work on hip stability and strength to help minimise the risk.
How will I know if I have MTSS?
In mild cases you may feel some slight discomfort in the medial aspect of the shin during a run. Usually if you reduce your training for a week, ensure that the pain does not worsen and gradually return to your activities it will settle. In more severe cases it is worth getting it checked out by a healthcare professional. The reason it is important to have it further investigated is because it is thought that MTSS is on a continuum and could potentially develop into a stress fracture.
The diagnosis of MTSS can be made using the Yates Criteria (2004)
1) Exercise induced pain: Posterior-medial border of the tibia
2) Pain on palpation of posterior-medial border of the tibia
3) Site of pain spreading over a minimum of 5cm
Two simple tests can also be utilised for the assessment of predicting MTSS; the shin palpation test and Shin oedema test. A diffuse pain on palpation of the distal 2/3 of the posterior-medial aspect of the tibia is usually associated with MTSS. Pitting oedema after a sustained 5 second hold of the distal 2/3 of tibia is also associated with onset of MTSS.
(images taken from Newman et al. 2012)
How do I know I haven’t got a stress Fracture?
It can be hard to differentiate between MTSS and stress fractures. On assessment focal bony tenderness and associated night pain as well as sharp pain on loading can indicate a stress fracture. By having it further investigated with imaging is the best way of identifying stress fractures. An X-ray can sometimes miss these and therefore an MRI scan is probably the most useful. If a stress fracture is suspected or diagnosed then it is important that a sustained period of rest is completed to allow time for healing and then a gradual return to activity as guided by your therapist.
How do I treat MTSS?
The first line of treatment is to redu
ce the amount of load being transmitted through the bone. This may therefore require a period of rest from impact training in the acute phase for 2-6 weeks. In order to maintain CV fitness, cross training can be utilised (such as cycling, swimming, aqua running). To offload the affected area, orthotics, tape and supportive shoes can be utilised. These may help reduce the traction forces being placed upon the bone. Compression socks have also been found to be useful for providing some pain relief.
Targeting areas of weakness and stiffness will also be important during the rehabilitation phase. For example working on ankle mobilisation and calf muscle length and proximal hip strength and stability will be important. T
here has also been some good evidence to support the use of shockwave therapy in the management of MTSS.
Building calf strength and capacity is going to also be an important factor in the management. As mentioned earlier, people with MTSS often present with a reduction in calf endurance and with the additional period of rest, things are likely to become more deconditioned. It is important that the whole calf complex is targeted (gastroc and soleus) and that a progressive strengthening programme is commenced.
Finally a gradual return to running programme should be implemented. By gradually increasing your running will allow for positive adap
tations of the bone and muscles to take place. This should then be closely monitored throughout the programme to ensure that training errors are minimised.
Closing thoughts
Hopefully this has given you some further information as to what MTSS (shin splints) is. I would always advise getting this checked out as there are differential diagnoses that can present in a similar way. We would also want to ensure we rule out any sinister pathology. Your therapist will be able to identify potential risk factors or deficits and the then target these in the rehabilitation phase and gradually guide you back to running.
As always, thanks for reading,
Josh
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