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Runners Guide to Shin Splints

The following article is taken from the Kinetic Revolution blog. You can link through by clicking on the hyperlink provided below where you’ll find a wealth of information and links to other professionals in the field on all aspects of running injuries and prevention. Or find the article below.

http://www.kinetic-revolution.com/what-causes-shin-splints-in-runners/

Shin splints, or Medial Tibial Stress Syndrome (MTSS) to use the more medical term, is an incredibly common injury amongst runners. In fact, some studies have reported shin splints to occur in up to twenty percent of the running population.

Out of all of the running injuries that I regularly treat, I think this one is the least well understood, in terms of exactly what’s going on.

It’s an injury that I have personal history with. When I took up running again, after a long absence, it was the first injury I got, and the resulting frustration, is what kick started my journey into wanting to better understand running injuries.

Like so many of the running injuries we see in clinic every day, shin splints is classed as a ‘overuse injury’. It does appear in other sports, but is certainly much more prevalent in runners.

In addition, it definitely seems to be a condition that affects novice runners more than fitter, more experienced athletes, the reason for this should become clear later on in this article…

SHIN SPLINTS: TYPICAL SYMPTOMS

In typical cases of shin splints, pain is usually felt two-thirds of the way down the tibia, just off the inside edge of the bone.

In the early stages of the condition, pain is usually felt at the beginning of a run and then normally subsides during the training session itself. Commonly, symptoms also tend to reduce a few minutes after a given run session has finished.

If the injury worsens, pain is felt in less intense activities and can be present at rest.

It is often painful to apply direct pressure to the affected area. Because the antero-medial border (front/inside) of the tibia is directly under the skin, pitting oedema, and even callus formation, can be felt on upon close examination in some cases.

This is thought to be a response of the periosteum to micro-fracture formation.

THEORIES

So what exactly is going-on to cause the pain of shin splints!?

As I mentioned earlier, the variuos mechanisms causing MTSS, and what structures are involved, are still up for debate.

Let’s look at a few of the more plausible theories…

THE SOFT TISSUES OF THE TIBIA

One group of suspects in this case, are the soft tissues of the tibia. The muscles of the calf, and the smaller muscles of the ankle, have their attachments along the tibia. Specifically, the tibialis posterior, flexor digitorum longus and soleus muscles, have been implicated as possible sources of injury.

The theory being, that tightness, weakness, or excessive movement at the ankle causes traction or tugging at the site of their origin on the tibia, leading to an irritation of the periosteum.

However, this theory doesn’t really stand up to anatomic scrutiny, in that, all of the above mentioned muscles, have their origins above the site of pain. It seems unlikely that traction of an origin site, higher up the tibia, would produce pain at the distal (lower), medial (inner) shin.

There is however, another soft tissue that does attach to the medial border of the tibia, in the location of the symptoms. That structure is the deep crural fascia (fascia is a thin sheath of fibrous tissue enclosing muscles and organs).

This structure has deep insertions to the medial tibial border, finishing at the medial malleolus (inside ankle bone). It’s highly likely that the above mentioned muscles will be continuous with this fascia.

Therefore, from an anatomical point of view, the deep crural fascia could tug on the periosteum, in the location of symptoms, and create the traction mechanism of injury detailed above.

DECREASED CALF STRENGTH

Some studies have suggested that smaller calf size, and decreased calf strength, could be connected with shin splints.

The theory being, that it is the bone tissue of the tibia itself, that is the source involved in the pain response.

Bigger, stronger calf muscles encourage the tibia to become stronger, and therefore, able to take greater loading.

Additionally, the calf muscles themselves being stronger, would mean they would be able to absorb impact forces directly, again taking the load off the tibia.

TIBIAL BOWING / BENDING

This alternative explanation, again implicates the tibia itself. With this hypothesis suggesting that the problem arises via micro-trauma to the bone, due to repeated bending or bowing of the tibia.

It is well known in engineering, that when you load a long, narrow structure (like the tibia)axially, e.g. place a force through the centre of the object, lengthwise, it will result in bending moments at the structure’s lowest cross-sectional area (the narrowest part). The narrowest part of the tibia is the distal third where symptoms of shin splints are commonly felt.

It is generally suggested by biomechanists, that the tibia bends in the sagittal plane (forwards and backwards plane of movement) when running, placing most force at the distal anterior section of the tibia. But this of course depends on form; dictating where and how you strike the ground as you run.

Think of this a bit like a pole vaulter’s pole…

As they approach the jump, they plant the pole ahead of themselves (similar to an over-stride when running). Subsequently, we you see this big, anterior bowing of the pole. Great for pole vaulting but not so good for shins!

If we factor in three potentially important elements, we see that this anterior bowing force, in many runners, will be shifted medially, to where the symptoms of shin splints are reported.

1. As the foot loads, pronation occurs, (we all do it to varying degrees) which will shift the ground reaction force more towards the medial shin, and cause more of a varus (side-bending) force in the tibia.
2. Pronation is usually coupled with medial rotation of the tibia, which also places more stress medially.
3. When we run, we tend to land more towards the midline than directly in line with our hip. This is because it’s easier to get our centre of mass over our base of support. The consequences of this, are that our tibias will absorb the ground reaction force at an angle, and therefore a varus (side-bending) force, will again, be applied to the medial tibia, at the part of the tibia with the least cross sectional area e.g. where most people with shin splints have their symptoms.

Additionally, the muscular contractions of our plantar flexors, namely soleus, can also cause a tibial bending moment. If you imagine the attachment site of soleus, at the top of the tibia, and its insertion at the calcaeneus.

As we go through mid-stance, and the soleus begins to contract to slow the acceleration of the tibia, the origin and insertion sites will be pulled towards each other, again causing an anterior bending in the sagittal plane.

It is important to note at this point, that bone stress is not a problem, if it’s applied at a gradual rate. Bone is an organic and dynamic structure. Like all living structures in the human body, it responds to stress by remodelling itself, to ensure it can cope with the demands being placed on it.

The problem comes, when the accumulated stress of training, outstrips the body’s ability to remodel the area. This gives us an insight into why this condition is more prevalent in novice runners, or less fit runners, because their bones have not adapted over time to the stress of repetitive, high impact exercise.

It also gives us another layer of evidence to illustrate that, when it comes to injury prevention, it may not be the sexiest intervention, but the most fruitful therapy is to obey the law of adaptation, and accumulate the stress slowly, giving your body’s tissues the chance to adapt and get stronger and therefore be able to withstand greater load.

The tibial bending theory has not been proven yet, but it certainly seems to me, to be the most persuasive of the current theories on offer. As always i’ll allow this to guide my practice, whilst keeping an open mind and following any further developments in the literature.

DIFFERENTIAL DIAGNOSIS

• Stress fracture – Interestingly, some authors feel that stress fractures are on a continuum with shin splints, whereas others feel they are similar but different conditions.
• Chronic exertional compartment syndrome or anterior biomechanical overload syndrome.
• Popliteal artery entrapment
• Tibial tumours
• Bone infections / Osteomyelitis

PREVENTION

Prevention is always the best medicine when it comes to running injuries. Shin splints are similar to most running injuries, in that the most effective way to prevent them is to respect the laws of adaptation. This means, firstly, listening to your body.

If you are feeling pain when running, it’s because your brain has decided, that a particular area of your body needs protecting. Usually, but not always, this is because too much stress, or load, is being accumulated in the painful area, and you are not leaving enough time in between stresses to allow the tissues to adapt.

So the key to injury prevention is gradual, patient loading.

Now, if you’ve gone past the prevention phase and are in the painful phase (and lets face it, if you’ve found this article, I imagine you’re in this phase already) the next sections will be helpful for you.

PAIN RELIEF

The reason that most people visit me is due to pain. Pain is often viewed as the problem. It isn’t. Pain is a symptom of the problem. Your pain system is complex and has evolved through millions of years of natural selection. It is essentially your alarm system.

Its purpose is to protect you, and alert you, to the fact something is not right. It’s not a nice feeling, but at the end of the day, it’s meant to be uncomfortable, otherwise you would ignore it!

Pain is your friend.

Dealing with pain is important, no-one wants to be in pain, it’s not a nice sensation at all and, to be fair, once we’ve worked out what the problem is and how to address it, the sensation becomes less helpful, so turning it down a bit is one of the early goals of physiotherapy.

Remember that we want to turn the pain down, but we have to work out why it’s is there in the first place, otherwise it’s like your burglar alarm going off, you getting annoyed and fed up of the repetitive, annoying sound and going to the box and turning it down.

It may make the noise a bit more bearable but does nothing to address the intruder in your house (a bit of a dramatic analogy, but you get the point).

When it comes to pain relief I try to keep it simple:

ICE

Ice works really nicely as an analgesic. Crushed ice appears to be more effective from the current research. Rough guidelines of 10 mins every 2 hours, if needed, are adequate (Remember to wrap ice in a damp towel to prevent ice burns).

Decrease the load on the sensitive area. Intuitively, if you continue to stress, the already over-stressed area, it will prevent healing or de-sensitisation. Decreasing the load can be as simple as rest, cross training or, my favourite option, running re-education – see below.

PAIN MEDICATION

Always consult your GP or pharmacist before taking any medication.

RUNNING RE-EDUCATION

The goal of running re-education is to assess an individuals running style, and see if, through subtle changes to their biomechanics, you can shift the load from the painful area, whilst not jeopardising their performance or creating an environment for another injury elsewhere in the body.

So in the case of shin splints, we are trying to reduce the anterior and medial tibial bowing.

Here’s some of the running cues that I like to try with this condition. It’s important to note that there is huge variability in what works for different patients.

Word of warning with these: If the cue is going to work for you, you should feel marked relief, and ideally no pain at all, within 30s – 1min of adopting the cue.

If you’re not getting any relief by then, try not to run through it.

If none of the below cues are working for you, then it may be time to see a physiotherapist, or other health care practitioner, for some advice, ideally make it someone who specialises in running injuries.

INCREASE CADENCE

One of my most used running re-education cues across the board. The best way to do this is with the aid of a digital metronome.

There are lots of free metronome apps, if you have an iPhone, or you can buy one pretty cheaply from places like Amazon.

There’s no set stride rate you should aim for so have a play around with it. Generally, I go for 5%-10% more than your current cadence and see what happens. You can always gradually increase it from there and re-assess the ‘experiment’.

The theory behind increasing your cadence is to decrease an over stride, get you landing closer to your centre of mass (COM) and with a straight tibia, as opposed to your tibia flicking out ahead of the knee.

As mentioned earlier this article, think of it a bit like a pole vaulters pole. As they approach the jump, they plant the pole ahead of themselves so you see this big, anterior bowing of the pole, great for pole vaulting but not so good for tibas!

If you can imagine the pole vaulter placing the pole down vertically, and not ahead of themselves, you will see a pretty crappy pole vaulter, but also less anterior bowing of the pole, that’s what we are looking for – less anterior bowing = less force through the painful area.

Read more about cadence training and metronome use here: Running Cadence: Research & Metronomes

INCREASE STEP WIDTH

Trying to move the load from the medial shin, to achieve less varus (side bending) tibial bowing. I try to bring about this change using a variety of cues. Generally, asking people to have some daylight between their legs or imagine running on either side of a yellow parking line, gets the right changes.

Recently, I’ve been getting my runners to run with a resistance loop just above their knees, and instruct them to keep the pressure on the band – this has been working really well.

STIFFEN THE ANKLE

The idea here is to decrease the amount of dorsiflexion the ankle goes through. Lessening dorsiflexion means less tibial bowing from the action of soleus, as it tries to decelerate the tibia as it moves into end of range dorsiflexion.

Stiffening the ankle also helps to pretension the muscles, so they can work reactively and elastically. Good for speed but also takes the load of the bone itself.

CHANGE THE DIRECTION OF THE GROUND REACTION FORCE

Again, we are trying to decrease the anterior tibia bowing. If we go back to our rubbish pole vaulter, as we discussed, if he places the pole out in front of him with forward and downwards force it will create anterior bowing.

However, if he plants the pole down with a backward and downwards force, it will not bow anteriorly, but posteriorly. Bad for a pole vaulter, but good in our tibial context! i.e the force will go more through the back of the tibia.

Any change in the direction of the ground reaction force, to a more backwards and downwards force, will decrease the load in the anterior tibia and may be enough for us to keep running without pain. To cue this, I often video them and freeze the frame of them running when their swing leg is at its highest.

From this position, I instruct them to push their leg back and down in a backwards tick type direction, using their glutes to perform the movement. Sometimes I’ll ask them to paw back on the ground (bit of a controversial cue from a performance perspective, but can just get them to direct the force more backward and down).

POSTURE

Encourage the patient to ‘run up tall’. I often use the ‘helium balloon attached to the crown of the head’ cue or get them to imagine their spines like a slinky toy, and wanting to open it up. This cue helps decrease an anterior pelvic tilt, or a forward lean from the waist.

Both of these mechanics lead to the centre of mass shifting forwards during stance. To compensate for this, you will have to over stride with the next step = more load on knee and shin area.

Usually I use a combination of the above. Have a play around with these cues and let me know what works for you. As always, never run through pain.

There are some occasions, when no matter what alterations you make, you can’t offload the area sufficiently and pain is still present. In those cases, it is wise to take a short break from running, to allow the area to settle some more.

Cross-training can be effective at this point, to maintain strength and fitness. Remember you only need to offload the painful area, not your whole body. I prefer aqua-jogging, or running on an alter-G treadmill (if you’re lucky enough to have access to one).

This way you can still work on technique, and keep your running specific movement patterns with very little stress on the musculoskeletal system.

OTHER TECHNIQUES THAT MAY HELP

ORTHOTICS / TAPING

Generally, I try to avoid orthotics or taping if I can, but they can still be great tools to offload an injured or sensitised area. Often a medial arch support works well to offload the medial tibia.

CALF STRENGTHENING

As mentioned earlier, weak calves have been implemented in shin splints. So seems like a good idea to strengthen these muscles as a way to create a stronger, thicker tibia, but also being able to take more load themselves.

CHANGING THE SURFACE YOU RUN ON?

Bit of a weird one this, intuitively you would think that running on softer ground, such as an athletics track, sand or grass, would be easier on the legs, but the literature suggests that when we run on softer ground our leg actually stiffens more to compensate for the softness, and the reverse is true when running on hard ground i.e. less stiff legs.

This has led many to suggest that it may be better for runners with shin splints to run on harder ground. I remember when I had my shin splints, I found it better running on softer ground, but might be worth bearing in mind if you find the pain is worse on softer ground.

RUNNING BAREFOOT OR IN MINIMALIST FOOTWEAR

Some evidence that this can shift the load from the shin and knee, more to the foot and ankle. Probably by, subconsciously, increasing cadence and landing closer to CoM.