For exclusive access to all our stories, including sequences, teacher tips, video classes, and more, join Outside+ today.
When my children were very young and seated in a highchair, they would deliberately drop pieces of food—one by one over the edge of the tray, each time delightedly watching them fall to the floor. By the time my third child reached this stage, I had changed my perspective. Instead of being annoyed, I told myself that she was just “experimenting with gravity.” That always made me smile.
When you practice asana, you are constantly experimenting or dancing with the force of gravity and its effects on a pose. If you are to understand how to practice, and certainly how to teach, you must be aware of how gravity “chooses” which muscles are working, and which are not, in each asana, and why this is so. This understanding is what I call movement literacy, and it is the guiding principle of my online and in-person course on experiential anatomy.
Movement literacy is based on the understanding that the body is an orchestra and movements are the music it creates. When you can see, feel, and understand the specifics of the body’s movements, not only do you become a better practitioner, but you now have the tools to help your students practice more safely and even potentially to help them eliminate pain when they struggle in an asana.
Here is an example: Both Supta Padangusthasana (Reclining Hand-to-Big-Toe Pose) and Uttanasana (Standing Forward Bend) are forward bends. Both poses are practiced by flexing the hip joints. But there is a big difference in which muscles are creating each asana. In Supta Padangusthasana, you begin by lying supine on your mat. To practice the pose, you exhale as you flex your hip joint, bringing your thigh toward your trunk. Your leg comes straight up, moving against the force of gravity the whole way. Finally, catch your big toe or hold on to your outer ankle or lower leg, depending on your flexibility.
The action of raising your leg up is created in this position by the hip flexor muscles that are found on the front of the body. These are principally the iliopsoas, the rectus femoris portion of the quadriceps, the sartorius, and the pectineus.
When you lift your leg up against the force of gravity, these muscles undergo a shortening contraction, also called a concentric contraction. The hip flexor muscles are creating the movement of bringing the thigh to the trunk, that is, hip flexion. The entire action is occurring against the force of gravity.
Supta Padangusthasana (Reclining Hand-to-Big-Toe Pose)
Begin by lying supine on your mat. Exhale as you lift one straight leg up, moving into hip flexion. Catch the big toe with your fingers, or hold your outer ankle or lower leg if your hamstrings are tight. This action, moving against the force of gravity, is created by the hip fl exors undergoing a shortening contraction against gravity.
But just because you are moving into hip flexion doesn’t necessarily mean that you are creating the movement by using your hip flexors. When you are standing up, for example, and bending forward to practice Uttanasana, it is actually the muscles in the buttocks and back thigh that are controlling the creation of hip flexion, not the hip flexors. Thus, the muscles that are creating hip flexion in Uttanasana are muscles on the back of the body: the hip extensors.
Uttanasana (Standing Forward Bend)
From standing, with your feet hip-distance apart, hinge forward from your hip joints, keeping a long spine. Notice how muscles on the back body, especially the hamstrings in the back of your thighs, are controlling the creation of hip fl exion, not the hip flexors. The hamstrings are working with the force of gravity to let you down gradually.
The hip extensors are the gluteus maximus and all of the hamstring muscles, except the short head of the biceps femoris. Plus a small percentage of the movement is created by the posterior fibers of the gluteus medius.
Hip extension is the movement of the femur backward when standing, like when you prepare to kick a ball. Or, in asana practice, extension of the hip joint occurs when you lift one leg up in the Adho Mukha Svanasana (Downward-Facing Dog Pose) variation often called Three-Legged Dog, or when you move into Urdhva Dhanurasana (Upward Bow Pose).
All of these movements are shortening contractions of the hip extensors. But the hip extensors are also active when moving into Uttanasana, which paradoxically is hip flexion. When bending forward in the pose, you are now moving with gravity. When you begin the pose by tipping the trunk slightly forward, gravity immediately begins to pull more and more of your body downward toward the earth.
The hip extensors are now undergoing a lengthening contraction. They are slowly letting you down, like you would let someone down with a rope over the edge of a cliff. The hip extensors are acting like a brake on the body to control the gradual descent into hip flexion. This is more metabolically efficient; you need less energy to move with gravity than against it. In other words, by using the hip extensors, the body uses less energy to create hip flexion. Without the lengthening contraction of the extensors, you would simply crash down onto your legs or onto the floor because the force of gravity is pulling you down.
Just the opposite occurs in the hip extensors with Salamba Sirsasana (Supported Headstand). Think about coming into Sirsasana with both legs straight. You prepare for the pose in hip flexion, with your arms and head in Headstand position, and your weight on the balls of your feet. You slowly move into the pose by creating hip extension against gravity as you lift both legs up, stacking your feet over your hips. You are moving into hip extension against gravity and therefore the hip extensors are creating the movement.
When you come out of Sirsasana, you are moving into hip flexion but the hip extensors are still controlling the movement. They are undergoing a lengthening contraction to slow the descent against the force of gravity and to protect you from injury.
Whether you are practicing or teaching yoga, it can be difficult to keep all the actions of muscles at the forefront of your mind. But if we begin to think first of the effect that gravity might be having on the body in a pose, it is easier to quickly figure out which muscles might need to be stronger, and which might need to be stretched.
In Sirsasana, for example, it might not cross your mind that the hamstrings need to be both stretched and strong in order to come up with two straight legs. In Uttanasana it might not seem like the hamstrings are doing most of the work of creating the pose, both as you descend and ascend. But the hip flexors in Uttanasana are not creating hip flexion, even though you end up in hip flexion. Because we swim in a sea of gravity, it is indeed the hamstrings that are mostly controlling both the ascent and descent.
Begin to notice in your own practice which muscles are activated as you practice. Start slowly with the poses offered here, and then begin to observe your muscle action in other poses. Not only will this be an effective way to study muscle actions, but it will help you appreciate even more how wondrously subtle and intelligent all of our movements really are.
About the Author
Judith Hanson Lasater, PhD, PT, has taught yoga since 1971. She is the author of nine books on yoga, including Restore and Rebalance and Yogabody: Anatomy, Kinesiology, and Asana. For more information, visit judithhansonlasater.com.
Take Judith Hanson Lasater’s Experiential Anatomy course, and put these principles into practice. Sign up for the online course today at judithhansonlasater.com/yj.