Our postures rely on a sound relationship between the soles and the ground. An unstable first point of contact destabilizes the body. Many who consult with me for pain and misalignment issues have weak feet muscles/tight tissues. This exercise is excellent to build your arches.
This client is undergoing my arch building protocol to change how his soles interact with the ground. The exercise above made him feel his bad side from the ankle all the way up to his shoulder. Some feel tension in their hands as they work their feet.
More info on the exercise:
