If you've ever wrung a cloth, or twisted one, you've seen how it get's stiffer the tighter you wring it. Apart from rolling the thighs in and out, the hip rotators, both internal and external can be used to a similiar effect. They can be used to tighten or stabilize the hip joints. In the same way the shoulder rotators can be used to stabilize the shoulder joint.
Rather than focusing on rotator muscles, the focus will be on actions, rotating inwards and outwards and also noticing how those actions feel. (That being said we will name those muscles.)
The descriptions below start with basic shoulder and hip rotations. These exercises ideally help you differentiate between internal and external rotation, so at least when you read on you'll know to which action I am referring to. In addition they give you a chance to feel the muscular actions that occur when you do either rotation. Your task then in the yoga poses that follow is to try to duplicate those actions.
In addition notice how the actions affect your yoga pose as a whole. Do the actions make the pose feel more stable or solid? Do they feel good? Do they feel "right"? Do they make the pose easier? Do they make the pose feel worse or simply different?
As you get more experience with the actions you can choose whether or not to use them. But first I'd suggest that you need enough experience to make informed judgements. That experience can include experimenting with these actions and with what you do around those actions. Is there a way to vary the tension that you feel when you do an external hip rotation?
A very simple standing shoulder and hip rotation exercise with a twist has the feet hip or shoulder width apart and parallel.
Turn the pelvis to the right so that you are twisting both hips. Then turn your ribcage to the right also so that you are twisting your thoracic spine.
With a twist of the pelvis to the right, the front of the right hip is closed. To accentuate this closing, roll the right thigh inwards. This uses the internal hip rotators of the right thigh. However you aren't just using them to roll the thigh inwards, in this pose you are also using them to help accentuate the turn of the pelvis to the left.
At the same time the front of the left hip is opened. To accentuate this opening roll the left thigh outwards. This uses the external hip rotators or the left thigh. These help to roll the thigh outwards but also help to turn the pelvis to the left.
You can duplicate these actions, or mimic them with the arms and chest.
Twisting your ribcage to the right relative to the pelvis, roll the right arm inwards and the left arm outwards. Do this with your arms down by your sides. Rolling the right arm inwards use the internal shoulder rotators of the right arm. These help to roll the right arm inwards. However, since the hands are not in contact with the floor, the arm only marginally assist in turning the ribcage right. With the left arm rolled outwards you are using the external shoulder rotators of the left arm.
Rest and then repeat the actions, turning the pelvis and then the ribcage to the right. Then roll the right leg and right arm inwards (internal rotation). Then roll the left leg and left arm outwards (external rotation.)
For external rotation of the legs, the inner thighs roll forwards. For external rotation of the arms, the biceps or fronts of the arms roll outwards. The opposite happens for internal rotation.
Each time you repeat the action to the same side notice where you feel the tension in your legs and hips when you turn your pelvis and rotate your legs. Likewise notice tension in your arms, shoulders and ribcage when you turn your ribcage and twist your arms.
Work at doing the actions smoothly. Hold the end postion and see if you can twist and turn deeper.
Activate your feet so that your arches lift and your feet grab the floor. You can also experiment with squeezing the knees (activating the muscles that act across the front and back of the knees.)
For the arms and shoulders, first feel your ribs. Try to open the front, sides and back of your ribcage. Create or redistribute the spaces between the ribs. Try to tighten the elbows and you can also try spreading the fingers and making them feel long for a full body experience.
So what then to do with the neck? Make if feel long. And turn it in the same direction as your pelvis and ribcage.
And as for your eyes, fix them on a single point or focus them inwards. Look inside your body.
Some of the standing yoga poses that these actions can be used in include triangle forward fold (parsvottanasana), triangle twist (pivrtta trikonasana) and warrior 1. You can also try it in chair pose.
Seated yog poses that you can use these actions in include seated forward bend with legs crossed, bound angle or butterfly yoga pose, frog pose, half splits, low pigeon and high pigeon.
You can also use them in backbending yoga poses like bridge and wheel pose as well as in forward bending yoga poses.
It can also be useful in poses where the arms support the weight of the body. Downward dog, chaturanga, table top yoga pose and reverse plank.
What follows are some examples of what I've tried. Use them as guidelines for your own practice.
Sticking with the feet shoulder width apart, we can experiment with doing the leg actions while doing a standing forward bend. Rest with your hands on your thighs, or shins or on the floor. Roll both thighs to the right (right leg rolls out, left leg rolls in), relax and then try it to the left.
In a bent forwards position it can be difficult to decide which way is left and right when turning the pelvis. So instead, don't worry about it and instead focus on twisting your legs.
Then rest. We'll return to this yoga pose momentarily.
We can now try the same thing in chair pose. Reach your hips back, bend your knees and reach your arms forwards. Roll the thighs to the right (right thigh rolls out left thigh rolls in.) Roll the arms in the same way (right arm rolls out, left arm rolls in.) Then return to center and then do it to the left. Then stand to rest and repeat.
What you may have noticed is that your pelvis twists as you do spiral your thighs.
When doing these actions in this yoga pose, keep your knees the same width apart. Allow them to move but keep them the same width as your knees.
Next while standing with legs straight, roll both thighs out, then roll both thighs in. Do both actions slowly and see how these actions affect your pelvis. For myself when I roll my thighs out my pelvis tilts forwards so that my pubic bone moves down. When I roll my thighs in my pelvis rolls back so that my pubic bone lifts.
Alternate both actions while doing the standing forward bend and then chair pose. When doing chair pose, because the knees are bent, work at keeping the knees foot width apart. Rather than letting them move in or out keep them still. You can roll your arms out and in with the legs.
In the forward bend, since when the thighs roll in the pelvis tilts back, you can go with this action and bend your spine forwards. Then since when rolling the thighs out the pelvis tilts forwards, arch your spine backwards.
Another point to notice is the feeling at the back of the thighs. I find that when rolling the thighs inwards the back of the thighs feel like they are spreading. This may make tilting the pelvis forwards easier.
Now lets return to the first action where the thighs roll in the same direction (both to the right or both to the left.)
Standing with the right leg forwards and the left leg back, with both knees straight and the pelvis facing the front, we can practice turning the pelvis to the right while rolling the right thigh and right arm inwards. We can roll the left thigh and left arm outwards. (The torso is still upright.)
With the arms on the front shin or the floor, do the same thing. Now turn the pelvis to the right and the ribcage. Reach the arms back or reach the left arm across the right thigh. Here again right thigh and right arm roll inwards while left thigh and left arm roll outwards. Find a slow and steady rhythm and practice activating and then relaxing.
Say you want to get more of a twist out of the second yoga pose, triangle twist (the first was triangle forward bend.) With the right leg forwards we can try turning the pelvis to the left but then turn the ribcage to the right. Since we want both legs to help in turning the pelvis, we then roll the right thigh out and the left thigh (the back thigh) in. Try to keep the arches of both feet activated while doing so.
Since the ribcage is turning to the right, the right arm rolls in and the left arm rolls out.
Both arms can reach back, or you can rest one hand on the floor or on the front leg. Try reaching the other arm out to the side.
…. right side open so right arm rolls out, left side closed so left arm rolls in.
At this point I should talk about the arms for a bit. If nothing else these exercises can be used to build awareness. One such awareness is that the upper arms can rotate at the shoulder. And your forearms can twist relative to the upper arm. When doing these actions focus on the upper arms. Do twist your forearms also, but pay more attention to the upper arms. One way to tell if your upper arm is twisting is to feel or watch the point of your elbow. To tell if your forearms are twisting watch the direction of your palms relative to your elbows.
And when your hands are on the floor this all changes. When your forearms twist with the hands on the floor or other surface, the upper arm and forearm turn together. When the hand is free, the upper arm can turn relative to the shoulder and the forearm can turn at the elbow relative to the upper arm.
Rolling the upper arms outwards (with the arms by the sides) the the points of the elbows with face the body. Rolling the arms inwards the points of the elbows with turn outwards.
For warrior 1, the normal tendency is for the pelvis to turn away from the front leg. The challenge is then turning the pelvis square to the front.
To help this action we can roll the back thigh out and the front thigh in. However we don't want the front knee to collapse inwards. And so we keep the knee stable, pointing over the foot but we duplicate the feeling of internal rotation.
For the arms, since the ribcage is square to the front, both arms can be doing the same action. With arms above the head, rolling the arms out causes the elbows to face forwards. Rolling the arms in causes the elbows to point out to the sides. I'd go with rolling the arms out. This also helps to spread the shoulder blades and it may give more room for the trapezius muscle to pull up on the shoulder blades causing them to lift.
Now these are suggestions. And what I actually do is try out both internal and external rotation to see how each feels. You can do the same thing. It helps if you know what you are trying to do in a pose, but even if you don't experiment and see what feels good or what makes the yoga pose you are doing feel easier, more comfortable or less fragile. You could describe it as a feeling of working hard but the work feels like good work that you and your body both enjoy.
Now then, to the floor.
In one of my yoga classes I wanted to teach these actions for the first time to some students but I wasn't sure how to start in a seated yoga pose. So I tried it with legs crossed. We did thighs rolling out with the arms reaching straight ahead and also rolling out.
The feeling is like the inner thighs are pressing outwards.
This action lends itself to low pigeon, particularly the screaming pigeon variation.
in bound angle pose, while sitting upright with arms behind the back I found that pressing the inner thighs forwards, internally rotating the thighs, helped get my knees down. And bending forwards this continued to be true.
In frog pose you can experiment with rolling the thighs, both thighs, inwards and then outwards. Or focus on pressing the inner thighs up and then down. You might also experiment with rolling both thighs in the same direction. You may find that this lessens the fragile feeling of this pose. For me I normally feel this deep in the hips, as if I' working on the connective tissue at the joint capsule. Spiralling the thighs seems to lessen the discomfort.
With legs wide in seated wide leg forward bend, you can do the same thing, roll thighs in and out but in this yoga pose keep the knees pointed upwards.
Do the same in hero pose (virasana) and even reclining hero pose (supta virasana.)
To get into chaturanga dandasana from a laying down position, my feeling is that spiralling the upper arms made it easier to stabilize the arms and so then it was easier to press forwards and down with the hands to lift the torso. Lifting all the way up into plank pose with a different manner and you can read about one way to modify this pose to make it easier to work towards the full pose (which is actually nothing more than a push up but with elbows pointing back.)
Getting into wheel pose, the same action can be used though it may take a while to get used to it.
Meanwhile we can get back to focusing on the legs. Using bridge pose as a warm up for wheel pose, you can focus on rolling the thighs out in order to push the pelvis up. The feeling I have is that of pushing up with the inner thighs. That being said experiment (or know that it is an option) with rolling the thighs inwards.
Do keep the knees the same width as your feet and have your feet parallel.
Make your feet active to keep them parallel as you lift up.
To get up in wheel pose first use your legs to lift your hips, then go up on to your crown. In this position, with your crown on the floor, focus on rolling the upper arms outwards. You elbows will move inwards. Try to keep this action and push up. Use your legs at the same time.
One set of yoga poses that use the arms includes table top and reverse plank. In table top the knees are bend. For both poses elbows are straight. Roll the arms out. Open your chest at the same time. And keep your knees the same width as your feet and try to roll the thighs out.
You may find that this pose is easier if you make your elbows feel strong, unbendable. To do so engage the front and back of each arm to tighten the elbow joint. A similar feeling can be created by trying to make your elbow feel straighter.
In reverse plank the knees are straight.
Usually with twists I admonish students to keep the pelvis level from side to side or square to the front. This is actually to build awareness. If you can hold your pelvis level and or square then that means that you have some awareness of the pelvis. You can then play around with it in different positions while being aware of how the new position relates to it being either square to the front or level or both. If you don't learn to play with the pelvis, one of the problems with holding the pelvis level or square, when doing twisting poses is that while it does focus twisting in the spine, it leaves the hips in a stabilizing role with no chance to work on the hips themselves, say to improve flexibility.