This is a screenshot I took during a session with one online client yesterday.
The green line in this image shows a pattern we refer to as Pronation.
Pronation is usually thought of as a single movement in the foot/ankle.
And it's thought of as a problem by most.
This is an incorrect point of view.
This screenshot shows the moment that this particular client discovered a genuine pronation for the first time he can remember.
While it's far from perfect, this was enough for his leg to erupt with muscle activation, to start trembling as these fibres feel unfamiliar loading. Loading that should be as normal as taking a leak first thing in the morning!
His foot has genuinely accepted the weight of his entire structure and surrendered itself into a 3 dimensional pronation. Loading into the full tripod of the big toe knuckle, pinky toe knuckle and heel.
It has lengthened, it has widened and there's an opening of the joints on the medial (inside) of the foot, a closing on the outside.
This rotates the tibia inward (internal rotation), as it moves with the Talus and Calcaneus bones below.
Look up at the pelvis, see the loaded side is hiked up?
The whole pelvis has shifted over the loaded foot, so that THE CENTRE OF MASS COMES INSIDE THE BASE OF SUPPORT
Read that again, and again and again.
The centre of mass comes INSIDE the base of support.
See what that does at the knee? Most call this Valgus.
But a valgus movement is NOT a valgus collapse.
A Valgus movement is part of the pronation action, the femur and the tibia have both internally rotated, yes by different degrees, but the knee joint has enough rotation built in to allow for this.
Where valgus knee becomes a problem is when the femur and tibia move out of rhythm and go outside of the knees ability to handle that movement
When all the bones and joints move in rhythm with each other, the muscles experience optimal loading.
Loading that is shared across all the muscle fibres as they all experience lengthening and loading as the weight of the structure loads them up.
This loading and stretching is what signals the muscles to contract and pull you out of that position.
If only a few muscles are loaded, only those few will do the work.
Think of all those people with tightness / pain in the peroneals, the IT band, the Piriformis area, the psoas area
Are those muscles doing all the work?
Are you missing this pronation movement?