Is there an official name for the alternating arms and legs position in this video? It is popular enough that it must have a name but I can’t seem to find one. Alternating arms and legs certainly work well enough. I teach this is a lot of my classes and it falls into the category of poses that drive me crazy. It is easy to lift the alternate arms and legs in a way that does the exact opposite of what is intended in the pose.
The lifted leg action is all about the gluteus maximus. The idea is to extend the leg backwards activating the big butt muscles that are often in need to retraining. It is my take that we all grip and tense our butts which, directionally and energetically, is the exact opposite of extension. There is a tendency for students to lift the leg too high to start or lift it with an external rotation of the hip both of which take us out of the gluteus maximus and hamstrings that are trying to lengthen the leg back.
Ideally, the lifted leg comes up  with the heel at the height of the top of the pelvis. The hip of the lifted leg should be in the same position of the hip of the leg that is still on the ground. This hike of the hip is the most common misalignment I see in the pose. If the pelvis is in the right position the kneecap and toes of the lifted leg will be point straight down to the ground.
Extending the leg higher than the pelvis is a fine thing to do in this pose but not if doing so changes the alignment of the pelvis. The leg should life higher with the assist of the balanced action of the inner and outer thigh muscles. If they work together the leg can lift higher without displacing the pelvis.
The arm should be an extension of the leg finding a straight line from the heel to the fingertips that it parallel to the floor. The upper arm externally rotates and the forearm internally rotates so that the palm of the hand is facing the cheek. For all of the extension of the arm and leg, the point of the pose is to establish core stability. When the arms and legs lift—ideally at the same time—the trunk should solidify so that the only thing moving are the extremities.
Alternating the arms and legs is another example of the abundance of basic core poses that are out there to help you strengthen and tone the body in order to live a long and pain-free life.
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