The posterior tibialis is an often under appreciated calf muscle. It is one of the main supports for the arch, it inverts the heel and assists with plantarflexion, and it is a key dynamic stabilizer of the foot and ankle complex. Because of its location underneath that gastroc and soleus, the posterior tibialis gets easily overshadowed by these larger muscles.
The strength and health of the posterior tibialis is important for maintaining the medial arch. Before discussing different ways to strengthen the muscle to help with pronation and flat feet I want to discuss a condition called Tibialis Posterior Tendon Dysfunction (PTTD). Not too long ago I wrote about Achilles tendon ruptures and how they are a result of a degenerative process of the tendon tissue. PTTD has a lot in common with Achilles tendinopathy, except applied to women. Whereas Achilles tendon ruptures typically occur in men, usually in their 30s and 40s, PTTD mostly happens to women after the age of 40.
Comparison to Achilles tendon problems
The posterior tibialis tendon runs along the inside of the ankle and attaches to the arch and underside of the foot. Weakening of the tendon leads to a progressive collapse of the arch. Similar to Achilles tendinopathy, the exact cause of PTTD is not well understood. Previously, the problem would often be mistaken for similar conditions like ankle sprains or Achilles tendinosis.
Research has shown the dysfunction is not the result of an inflammatory process as once thought, but rather a degeneration of the quality of the tissue that comprises the tendon. What causes the tendon to deteriorate still remains a mystery. There is some evidence that systemic diseases (e.g. rheumatoid arthritis) may affect of subset of people who develop the problem but when PTTD occurs as an isolated incidence, in the absence of other tendon problems throughout the body, the dysfunction is thought to be caused by mechanical stress or overuse.
Regarding the mechanical theory of PTTD there is also some debate about what came first: the tendon insufficiency or the flat foot? One study looked at x-rays of the non-involved leg in people presenting with PTTD. The researchers in that study concluded that a pre-existing flexible flat foot was often present and likely contributed to the development of the problem.
This is supported by other studies that have shown increased EMG activity in the posterior tibialis muscle in people PTTD and flat feet that could predispose the tendon to overuse. When the posterior tibialis tendon completely stretches out or ruptures there would likely be a further collapse of the arch due to the increased strain transfered to other structures.
If the origin of the problem is mechanical issue, than a prevention strategy should be aimed at reducing abnormal stress on the posterior tibialis and performing exercises that strengthen the muscle and tendon. In order to relieve the stress there are two basic options. Orthotics or a program to correct the mechanical problems causing flat feet.
There is some evidence that orthotic inserts can prevent the muscle from being overworked. In my view this is more a compensation for the problem than it is a solution. Adopting the orthotic approach means being chained to using the insert. Wearing an orthotic may mask the symptoms, but the bad biomechanics will still exist and will likely recur whenever the person is not using the device.
Prevention and Management
A better option would be focusing on all the contributing factors causing the muscle to be strained, and this would include most of the biomechanical faults that are associated with flat feet: limited ankle mobility, calf inflexibility, weak arch supporting muscles, poor posture and hip strength. A recent study in the Journal of Orthopedic and Sports Physical Therapy showed that women with PTTD had not only weak ankles but weak hip muscles as well.
For individuals in the early states of PTTD there is mounting evidence the a program involving posterior tibialis strengthening exercises, and in particular eccentric type exercises, is effective in reducing symptoms and improving function. This makes since, given the similarities of this problem with Achilles tendinopathy, as eccentric strengthening is currently the gold standard intervention for treating the Achilles tendon. I would propose that PTTD and Achilles tendon problems are very closely related. The reason women get PTTD and men tear their Achilles may be be due to some yet unidentified variable that predisposes each gender to one and not the other.
Here are two videos that are helpful demonstrating some basic exercises that target the posterior tibialis.
For more specifics about the PPTD risk factors and symptoms you can visit its stand alone page on in the injury section of the site found here.
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