First, internal rotation is described as the rotation of a joint towards the midline in the transverse plane. For example, if we are standing with are arms at 90 degrees to our sides and elbows flexed at 90 degrees with the palms facing the wall in front of us (like we are making a field goal), if we rotate our palms down in this position without letting the elbow drop, this is internal rotation of the humerus bone at the shoulder joint.

Now, more important that the anatomical definition of internal rotation is what we use internal rotation for (it’s more than just mobility to achieve different positions). Internal rotation is necessary for force creation! When approach the bottom of a squat for example, we are lengthening muscles and moving through joint positions as we control the descent. This is more of a globally externally rotated state as the body and joints create space for the bones to move in. Eventually, we need to overcome these positions and an internal rotation state is needed to close the joints and take space away.

The squat is broadly a movement of hip flexion, knee flexion, and ankle dorsiflexion. These motions also require femur external and internal rotation (more external) and tibial rotation. Don’t forget about the pelvis, which needs to be able to flex and extend as the sacrum nutates and counter-nutates. That being said, we also need strength in the core to create stability for the lower extremity to move. So, there is a lot going on!

To summarize, we often think of hip hinging as a deadlift or some deadlift variation, but there is much more we can do that utilizes the hinge. For instance, in sport we are hinging and creating force from a hinged position constantly. Think of a lineman in 3 quarter stance or tennis players reaching low and exploding back out of the position. CrossFit of course uses the hinge in all deadlifting variations but we can also see it in motions like toes to bar and kettlebell swings.