Abduction, adduction, and rotation

Opening scene

Stand up and open your right leg out to the side.

Easy. Now, while keeping the same leg open to the side, check where your kneecap is facing.

In most people, the kneecap has turned upward instead of forward. So while opening your leg to the side, you did one more thing: without noticing, you turned it outward.

Two separate actions, in a single move.

Now the hard part: keep the leg at the same height and try to turn the knee forward again.

The leg probably dropped.

This lesson is about why that happens, and about why the name of a movement is often not a single word.

What this lesson covers

First we'll define the two actions tied to the midline: moving away and moving back toward it. Then we'll open up the rotation actions, and you'll see where internal and external rotation are measured from. After that we'll talk about why these actions almost never come alone, because joints like the hip and shoulder can perform more than one action at the same time. Then we'll get to the most visible result of this in yoga poses: two poses that look the same can carry completely different actions. We'll work through this with sixteen examples. By the end of the lesson, you'll be able to tell how many actions a joint is performing at the same time.

Starting point

In the previous lesson, you learned the sagittal plane's two actions. Now come the actions of the two remaining planes.

In the frontal plane, meaning the plane that goes sideways, there are two actions, and both are measured against the midline.

There's a simple way to avoid confusing the two words: adduction contains the idea of "add" — you're adding the limb back to the midline. Abduction means moving away — it comes from the same root as "abduct," to take away.

In the transverse plane, meaning the rotation plane, there are two actions as well.

Notice: in rotation, the limb doesn't go anywhere. Your leg stays in place, but the kneecap faces inward or outward. The location doesn't change, the direction does.

Now the critical point. These four actions and the previous lesson's two actions can happen in the same joint at the same time.

Mechanism

Which joint goes in how many directions

Joints aren't equal.

The hip and shoulder move in all three planes. That means they can go in six directions at once: forward, backward, opening to the side, moving back to the midline, and turning inward and outward. These are called ball-and-socket joints, and they're the ones with the greatest freedom.

The knee, elbow, and ankle, by contrast, work mainly in a single plane. The knee does have some rotation, but only while it's bent, and it's very limited; looking for rotation in a straight knee pushes against the protective limit we talked about in the previous lesson.

The spine can also rotate and bend sideways; but as you saw in the previous lesson, this capacity is distributed unevenly from region to region.

Actions don't come alone

Now, the real idea of this lesson.

If the hip can go in six directions, it's inevitable that a single movement sends it in more than one direction at once.

Remember the experiment in the opening scene. When you opened your leg to the side, you performed abduction. But once the leg reached a certain height, it also had to rotate outward to keep going. Your body did this without you asking for it, because continuing without rotating wasn't possible.

The consequence is this: an instruction like "open your leg to the side" doesn't describe a single action. If how far to open it and with what rotation isn't specified, everyone finds their own easiest combination.

And those combinations work different places. An externally rotated sideways opening and a neutral sideways opening are two different versions of the same pose, and they load different tissues.

Looks the same, isn't the same

Now let's get to what this looks like in yoga poses.

Two people are doing the same standing pose: feet wide, arms at the sides. In a photo, they look identical.

The first person's front foot is turned outward and the hip is in external rotation. The second person's front foot faces forward and the hip is neutral.

Not the same pose. The same image.

Being able to see this distinction is the foundation of adapting a class instruction to your own body. When a teacher states an arrangement, if you can read which actions that arrangement contains, you'll also know what to change when it doesn't fit your hip structure.

The arm's movement across the front

There's one more action, and it comes up very often in yoga, but it doesn't quite fit any of the four main names.

Open your arm out to the side at shoulder height. Now bring it forward, across the front of your chest.

What did you just do? The arm didn't drop down, so this isn't quite adduction. It didn't go up either, so it isn't flexion. It moved forward, in a horizontal plane.

This movement is called horizontal adduction; the opposite direction, opening the arm out to the side and back, is horizontal abduction.

Eagle arms, arms wrapping around the chest, every arm movement that crosses the front of the torso uses this action. So does bracing the arm against the opposite knee in twisting poses.

Why is it worth learning separately? Because a restriction in the shoulder in this direction never shows up in folding forward or raising the arm overhead. It only appears when the arm crosses the front of the torso, and the person usually says, "my back is tight." When a restriction has no name, its location can't be found either.

A fourth action

One last concept, because you'll run into it.

This is what you're doing when you swing your arm around in a circle. It carries a single name, but it's a sequence of four actions, and that's why it scans a joint's entire range in a single motion. That's why it's used so often in warm-ups.

One last warning, because this gets confused often. Turning your palm up and down isn't shoulder rotation; it's the two bones of the forearm turning over each other, and it carries its own names. The way to tell them apart is simple: hold your elbow bent at ninety degrees and against your body, then turn your palm. If the shoulder doesn't move at all, what's rotating is the forearm. This distinction is useful in every pose where the hand is on the floor, because whether the wrist feels comfortable usually comes from the forearm, not the shoulder.

Reading the examples

Master layer

Now let's refine this a bit.

I described simultaneous action as if it were a difficulty. In reality, it's the body's efficiency. If joints worked in a single direction, every movement would need its own separate joint. Combination is what makes a large number of movements possible with a small number of joints. So the goal isn't to keep actions separate from each other; it's to be able to separate them, and then combine them on purpose.

Second nuance: the reference that rotation is measured from. Internal and external rotation are a limb turning around its own long axis, and that axis shifts position as the limb moves. External rotation measured with the hip in flexion doesn't give the same number as external rotation measured in neutral. This is why a rotation measurement is always recorded together with the position it was taken in; a rotation number without a position can't be compared.

Third, the cost of isolating an action. Locking a joint into a single direction and training only one action is valuable for measurement and learning, but it isn't enough on its own in the long run; no movement in daily life is isolated. Isolation is a teaching tool, not a training goal. The next two lessons will do both of these in order: first isolate, then combine.

Fourth, and the subtlest point: individual variation in hip structure affects every action in this lesson, and this is exactly where the most argument in the yoga world comes from. The difference between two people's external rotation range isn't usually a difference in training, it's often a difference in bone; and an instruction like "everyone should reach this angle," given without knowing that, pushes the joint to its limit in some bodies. Adapting an instruction isn't disobedience; it's exactly what this lesson is teaching.

Common mistakes and misconceptions

Practice

Keep in mind

Abduction is moving away from the midline, adduction is moving back toward it; in rotation, the limb doesn't change place, it turns around its own axis.

The hip and shoulder move in three planes at once; in these joints, simultaneous action is the rule, not the exception.

Part of opening the leg to the side opens up through external rotation; a range measured without fixing the rotation is the sum of two actions.

Two poses that look identical in a photo can carry different combinations of actions; this is why you don't copy the shape, you target the action.

A rotation measurement is recorded together with the position it was taken in; a rotation number without a position can't be compared.

Bridge to the next lesson

You now know the name of all six actions. Now it's time to find them one by one in your own body. The next lesson is a lab: a fourteen-minute, guided scan. You'll move through each joint in turn, isolate each action, and record where it stops. Every term from this section will take on flesh and bone there, in a single session.