A thread on how to use the shin angle and foot position to bias certain muscle recruitment & biomechanics in exercise

The shin angle is a lens into more simple exercise selection specific to human movement.

Think about a sprinter taking off in acceleration with a forward shin..

angle. It would make sense to train that into the weightroom, right?

We have three primary phases of gait with three different shin angles and three different muscular orientations:

Heel strike: Negative shin angle
Mid-stance: Vertical shin angle
Late stance: Positive shin

HEEL STRIKE

Here, the pelvis is biased towards an externally-rotated state with the foot in supination.

The shin angle is more "negative" as that is an effective position for the leg to be in to strike the lateral border of our heel. This is a heavily eccentric phase of gait.⁣

To bias a negative shin angle, we can elevate the heel. This will allow for increased eccentric activity of the external rotators like the glutes.

I like this for someone who can produce a lot of force, but can’t accept it as well. Think of your “tight” but strong athletes.

MID-STANCE

This is the phase of internal rotation. The shin angle becomes vertical to allow for a perpendicular line of force going into the ground as we load our bodyweight over that side.⁣

The foot is biased towards pronation and at this point.

To bias internal rotation and a vertical shin, we can elevate the ball of the foot. This will also help pronate the foot to allow for more internal rotation at both the legs and pelvis, as pronation is coupled with those actions in the gait cycle.

This will also help people “hinge” better because it allows for an easier posterior translation of their center of mass.

This can be applicable to things like deadlifts to prevent excessive lumbar flexion.

LATE STANCE

This final phase is also one biased towards external rotation, but more on the forefoot. I like to think of it as more “concentric external rotation”.

This phase can be thought of as a highly propulsive phase of gait once the heel starts to lift off of the ground.⁣

To bias a forward shin angle, the rear foot elevated position is great for this.

This pushes the weight onto more of the forefoot to allow for more of that “concentric external rotation”, allowing the glutes and hip extensors to work as they would in activities like sprints.

I’m a fan of anything that allows for less coaching and the outcome we want to achieve. Using foot constraints is an ideal way to do this.

You can also pair this with things like different types of loading to maximize the outcome you want. More on that here: https://twitter.com/conor_harris_/status/1301664826142334977