The feet are often the literal foundation of yoga poses, yet they are largely overlooked. And for good reason: it's hard to be aware of the feet, as they're so peripheral, and our awareness tends to center on our bigger muscle groups.
I remember in one of my first yoga classes, the yoga teacher told us to lift and spread our toes. I looked down at my feet and attempted to follow her directions, but nothing happened. But here's the thing: even by just attempting to spread my toes, muscles in my feet and lower legs were activated, which is the ideal outcome. Through repetition and practice, you can learn to build awareness through the soles of the feet.
Let's take a look at how to use our feet to properly align our body:
Stand with your feet hip-width and rock forward and back, shifting the weight between the balls of your feet and toes, and your heels. Keep your knees a little soft as you do, and try to find the place where the weight feels balanced between the front and back of each foot.
Once that is established, lift one of your feet in the air a couple inches. On your standing foot, roll in and out on the foot and discern the difference between the inner and outer edges. I learned a lot by exaggerating these actions, and looking down to see the weight shift on the foot.
You may already know if your feet tend to pronate (roll in) or supinate (roll out). For supinators, you'll notice that when you emphasize pressing through your inner foot, there's muscle toning around your ankle, and up along your outer shin.
Whatever the patterns are for you, here are a few yoga poses to help build awareness of the feet, and begin to see the connections between the feet and other parts of the body.
In forward folds like Standing Forward Fold and Wide-Legged Forward Fold, weight tends to shift into the heels. Try bending your knees in these poses, and shifting your weight forward until you feel as much weight in the balls of the feet and toes as your heels. Then keep that balanced as you press your hands down and forward to access a deeper stretch.
In asymmetrical standing poses like Warrior II that have one bent leg, the bent leg will tend to do more than its share of work. Check out this video on transferring half of the pose's work into the straight leg, and note how that changes not just the feet, but also the pelvis, legs and torso.
Standing balancing poses like tree pose benefit greatly by balancing the action in the feet. If your knees lock (hyperextend), weight will dump into the heels, and balancing will be difficult. Feel it in tree pose: bring your left foot into your inner thigh or shin. Keeping your right knee bent an inch or so, shift weight both forward and back and in and out on your standing foot until it feels balanced. Notice how that engages muscles around your legs. As you press your leg straighter, think of extending from your pelvis directly down through a straight line in your leg, rather than pushing your knee back (and thus shifting the weight into your heel).
You'll find this essential as you move towards more complicated balancing poses, including turning your gaze up towards your thumbs in Tree pose. Try it!