Oftentimes we mistake hard abs for core strength, but in yoga we want to cultivate a deeper understanding and connection to our own core.
Adductors
The adductors are the muscles of the inner thighs. Often addressed in the instruction of asanas, the inner thighs are required to inwardly or outwardly rotate, depending on the pose. Also, they can be pulled up toward the inner groins to assist the deepening of the groins into the body. Adduction moves the legs toward the mid-line of the body; connecting with the adductors helps us draw the action of the asanas into the body's core. When you walk, you may turn your feet out or feel like your moving in different directions. If you bring your awareness to your inner thighs, have the sense of them moving toward the space behind you, your gait feels more centred.
If you don't feel the connection, don't worry about it. Just know that by toning the adductors you are connecting to your core, including the stabilizing transversus abdominus, whether you feel it yet or not.
Supta ardha pavanmuktasana
Connecting to this 'core line' is helpful in a variety of poses. Supta ardha pavanamuktasana is an easy way to make the connection to this core line.
Urdhva prasarita padasana
Also, feel your abdomen. Is it bulging? Can you keep it wide as you draw the leg up? If not, move a little closer to the wall.
Do the other side.
Repeat several times. Each time the heels come to the wall, let the touch be light. Also, connect to your core line. Imagine the block between the thighs and act as though the two legs were one.
When you are finished spend some time relaxing the abdomen. Though we want strength in our abdominal muscles we also want to maintain a softness too. Otherwise, our breathing can become restricted and our abdominal organs constricted. Lying on the back with knees bent and hands on the belly offers you a connection to this softening. Feel how the belly moves with the breath. Widened out on inhalation. Relaxed down on exhalation.