The Lunge Test; forget ankle range, think ankle stiffness

I first came across the Lunge Test back in 2006 whilst reading a thread on Podiatry Arena.  It was at a time that my thinking was changing significantly with respect to what I had been taught during my undergraduate degree (2000-2003) and consequently the way I assessed my sports patients.  As undergraduates we were taught how to assess an ankle joint, and this primarily consisted of testing its range of motion by seeing how much you could push the foot towards the leg (a motion we call dorsiflexion), from a starting position with the ankle at 90 degrees, when a patient was lying supine on the examination couch.  We were looking to see if the patient had 10 degrees of dorsiflexion from the starting postion – a golden figure which was considered ‘normal’ at that time and which we were informed all individuals required.

The more I read the more I discovered that 10 degrees as a normal value was erroneous (infact it was not possible to even find the reference that this figure originated from).  What happens if you walk slower, or faster? What happens if you run? Was 10 degrees still valid?  The truth was that ankle range seemed to be hugely variable, and both subject and activity specific.

Then there was the actual method of assessing the ankle range – how hard should we push the foot when measuring dorsiflexion? Common sense would suggest we should apply as much force to the foot as is applied during gait.  Could we physically apply this much force?  Probably not.

At the same time I was trying to take in the bombshell that 10 degrees of ankle dorsiflexion was no longer something I needed to worry about I was reading a lot of work by Dr Kevin Kirby; a Sacramento based Podiatrist and Professor of Biomechanics who was pivotal in highlighting to me (amongst many others I’m sure) the importance of thinking more like an engineer.  In the discipline of engineering terms such as flexibility, mobility and rigidity are not used as they lack the precision to be mathematically quantified.  Instead the term ‘stiffness’ is used, and this describes motion or deformation in response to an externally applied force.  So when applying this concept to the ankle joint instead of reporting simply how much it moves (its range), we should instead consider how much it moves when various forces are applied to it (its stiffness).  Given that the foot and ankle are predominantly asked to perform their daily functions during weightbearing activity ‘stiffness’ seems much more relevant than non weight bearing range of motion.

So after abandoning non weightbearing ankle range and the mythical 10 degrees of dorsiflexion from my thought processes, and getting my head around the concept of stiffness Vs range of motion I stumbled across the Lunge Test – a weightbearing assessment of the ankle joint range which factored in the individuals body weight.  This is a test which has been shown to have very good reliability / repeatability (Bennell et al, 1998) and prospective studies have also shown it to be predictive of injury (Pope et al, 1998; Gabbe et al, 2004).  There are actually very few clinical tests we perform which have been shown to be prospectively predictive of injury so this is a test which should certainly not be left out (especially when screening uninjured sportsmen and women).

So how is the test performed?

1. Patient stands against wall with about 10cm between feet and wall.
2. They move one foot back a foot’s distance behind the other.
3. They bend the front knee until it touches the wall (keeping the heel on ground).
4. If knee can not touch wall without heel coming off ground, move foot closer to wall then repeat.
5. If knee can touch wall without heel coming off ground, move foot further away from wall then repeat.
6. Keep repeating step 5 until can just touch knee to wall and heel stays on ground.
7. Measure either: a) Distance between wall and big toe (<9-10cm is considered restricted) or b) The angle made by anterior tibia/shin to vertical (<35-38 degrees is considered restricted)
8. Change the front foot and test the other side (symmetry is ideal)

It is worth remembering that there are some validity issues with the wall to big toe measurement with respect to the proportions/ratios between an individual’s leg length and foot length.  Anyone who is very tall is likely to have the minimum distance required and anyone who is very short will probably not have the minimum distance; therefore it is generally considered better practice to use the tibial angle when interpreting the results.

So what does this test mean?

A restricted Lunge test essentially suggests there in an increased ankle joint dorsiflexion stiffness.  Research tells us this may increase an individuals risk for lower extremity injury.  It is also something which will often be considered by a Podiatrist when recommending footwear or foot orthoses for someone who is already injured.  The test is generally performed when shod (to allow for the heel height differential of the shoe) and whilst wearing orthoses; modifications are made as required in order to achieve an appropriate tibial angle.  It may also dictate the appropriateness of concurrent joint mobilisations or a soft tissue stretching programme.

References (please contact me if you would like a copy of any article)

Bennell, K. L., Talbot, R., Wajswelner, H., Techovanich, W., & Kelly, D. (1998). Intra-rater and Inter-tester reliability of a weightbearing lunge measure of ankle dorsiflexion. Australian Physiotherapy, 24(2), 211-217.

Gabbe, B. J., Finch, C. F., Wajswelner, H., & Bennell, K. L. (2004). Predictors of lower extremity injuries at the community level of Australian football. Clin J Sport Med, 14(2), 56-63.

Kirby, K. A. Foot and Lower Extremity Biomechanics Volume 3: Precision Intricast Newsletters, 2002-2008. Precision Intricast: Payson, Arizona, 2009, p50.

Pope, R., Herbert, R., & and Kirwan, J. (1998). Effect of ankle dorsiflexion range and pre-exercise calf muscle stretching on injury risk in Army recruits. Australian Physiotherapy, 44(3), 165-172.

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