Gait Parameter: Ankle Rocker during the Squat as a predictor for Shin Splints.
Here is a brief video we shot in our clinic. One of the primary assessments we do with all clients is a basic squat. No a “potty squat” were the tibia remains vertical and the hips press backwards, just a basic squat where the knees come forward. We do this with toes down and toes up.
We shot this video so that we could have some visual to talk about a few things.
1. Why toes up ? You have read it here before on our blog. Raising the toes is done by use of the log and short toe extensor muscles (Extensor digitorum longus and brevis, EDL, EDB and of the hallux extensors EHL, EHB). When we activate the extensors the toes dorsiflex around the metatarsals and the toes elevate. This activates the windlass mechanism. This mechanism tightens the plantar fascia thus shortening the distance between the metatarsal heads and the heel. Thus, the arch is driven up. This is why we harp on gaining toe extensor strength in flat footed and hyperpronators. Go ahead, stand up, raise your toes and feel the arch lift. It is a solid biomechanical phenomenon.
So, why do the squat with the toes up ?
Because when the foot is weaker than it should be a squat can allow the arch to drop too much during the down-squat. If the arch drops the foot could pronate more than necessary. This can drive subtalar joint motion which can fake out the true squat determination and the true determination of available ankle rocker. The client will be able to get deeper into the squat but for assessment purposes this will be a fake out. We want to know true available functional range at the ankle mortise joint (tibial talar joint). With the toes up, the arch is maximized and cannot drop unless the toes drop. As you will see in this video, you can thus see the true ankle rocker in this client is barely sufficient however it is likely enough (100-110 degrees) for normal gait in the sagittal plane.
What if when they do this there is little if any rocker, less than this guy?
Then to get more (100-110, ie. 10-20 degrees past vertical) they will have to compensate. We talk about the strategies in this old video of ours (LINK HERE). One of the best ways to compensate is to pronate through the arch more than normal. This will drop the arch height and carry the tibia forward enough to allow for forward motion. Sadly, this increased pronation can do alot of things. One is to carry the knee medially and this can create patellar tracking issues or IT band tightness, to name just a few.
So, what is our point today ?
- You need to make sure your assessments are telling you what you need them to tell you.
- Sufficient toe extensor strength and range is critical in the gait cycle to ensure sufficient ankle rocker occurs at the tibial-talar joint and not somewhere else you do not want it ( a compensation). Any strength you put into a client who has insufficient true ankle rocker is strength into a compensation pattern. Can you say heightened eventual injury risk ?
- Ability to find the foot tripod is a skill. It needs to be developed in a simple skill like we show here and then the sensation can be carried forward into gait and running.
- A forefoot varus or forefoot valgus (please read our foot type blog posts over the past 3 weeks) can impair the foot tripod and thus the true ankle rocker.
- Make sure the knees hinges straight forward in this ankle rocker-squat test. If it is not a forward bend you must consider foot pronation excess, tibial torsion, hip version or torison, or simply the weak foot issues we are talking about here today.
- This is a form of homework for our clients, just want you see above in the video. We add layers to this as the gain strength. But that is a topic for another day.
This is a huge predictor and problem in chronic shin splints ? You bet ya it is ! It may be the main missed deficit we see in shin splints (both anterior and posterior shin splints). There is lots more to this topic, but we will stop here for today.
Shawn and Ivo…….. you have to know what you are seeing. And as Johnny Nash once said in his song
I can see clearly now, the rain is gone,
I can see all obstacles in my way
Gone are the dark clouds that had me blind
It’s gonna be a bright (bright), bright (bright)
Sun-Shiny day now that i understand ankle rockers better.”