Funky Foot Drop

Ever hear of the funky new dance move called the foot drop? It’s kind of like a booty drop but a little more neurotic in nature! In all seriousness, there is a pathologic musculoskeletal condition called foot drop. This is when you have difficulty bringing your toes towards your nose, also known as dorsiflexion at the ankle joint. There are many causes of foot drop ranging from stroke to multiple sclerosis, but a more common cause is compression of the deep branches of the common peroneal nerve.

Example of foot drop. Credit Everyday Health

The muscle that allows your foot to come into dorsiflexion is the anterior tibialis. It’s the muscle in the front of your shin (tibia and fibula) that originates on the lateral aspect of your tibia and inserts on the medial cuneiforms in your foot. This muscle is innervated by the deep peroneal nerve, which is a termination of the common peroneal nerve; nerve roots L4, L5, and S1. The important piece of information here is that it comes off the common peroneal nerve; a nerve that wraps around the head of the fibula before moving inferiorly down towards the foot. This is a common point of nerve injury as the head of the fibula is readily palpable and exposed.

Anatomic location and exposure of the common peroneal nerve. Credit OrlandoNeuroTherapy.

So why am I talking about this? About two months ago, I was doing legs in the gym and was using the seated leg curl machine. This machine targets the hamstrings nicely through the way it positions your legs. But for it to get sufficient leverage it requires a foam covered bar to come down over the front of your shins. While I was using it I noticed that I had a slight foot drop in my right foot.

With the suspicion of an acute nerve palsy I decided to investigate what was going on. It appears that the top bar of the machine was pushing up against the head of my fibula thereby compressing the common peroneal nerve. This of course went away, but I wonder what the long term damage would be for someone who uses this machine several times a week over the course of a long period of time? How many people in the gym have a foot drop because of this? Can we develop a machine that is more friendly to our anatomy?

Top pad causing point of compression.

Now I use the machine without bringing that top bar down. I’m still able to target my hamstrings efficiently however, I am not able to use nearly as much weight.

Let me know if you experience this same problem!