The feet and toes play an important role in making sure that your ankles, knees and hips fall in alignment. When working out, walking and going up stairs, there is a tendency for people to roll to the outside of their feet and lift their toes.
This results in a collapse of the knees and a shifting of the hips from side to side. A way to test for your big toes activation is by putting a band under your big toe and making sure to keep the band pinned down when performing squats.
There are 4 points of contact that you should have on your feet when standing, squatting, lunging and deadlifting; your weight dispersed evenly across your (1) heel, (2) forefoot , (3) big toe and (4) a little bit of weight on the outside of your foot.
When properly driving the big toe into the ground, it will become easier to engage the glutes and stabilize the knees and hips.
The feet and glutes work together to make sure that your lower half stay aligned. To properly activate your big toe, drive it into the ground, do not let the ball of your foot come off the ground. This will cause the foot to roll to the outside. Instead learn to activate your arch and lower leg to lift your arch upward and drag your forefoot and big toe back toward the heel maintaining contact with the ground.