What is the sagittal plane theory of foot biomechanics?

Foot biomechanics is a complex activity as there are so many bones in the foot and muscles controlling the foot that can be difficult to understand. There are many different theories on foot function that further complicate it. Sometimes it does get so complicated it is hard to understand. PodChatLive is a weekly live conversation for the regular education of Podiatrists and others who may be interested. There have been several episodes of PodChatLive devoted to the topic of the different biomechanical theories and ways to understand them. The livestream goes out live on Facebook and then is later uploaded to YouTube. Every livestream episode has a different person or number of guests to go over a different area each time and several episodes have been devoted to biomechanics. Questions are replied to live by the hosts and guests while in the livestream on Facebook. There is also a PodCast version of each show on iTunes and Spotify and the other usual podcast options. They've developed a big following that keeps growing. PodChatLive is regarded as one of the ways in which podiatrists could get free continuing education credits on biomechanics.
One of the guests that they had on to talk about the sagittal plane facilitation theory of foot biomechanics was Howard Dananberg. Howard is widely considered as the podiatrist that started the understanding of this theory of foot function. He talked about what it was that set him off down that pathway of his approach to the understanding foot biomechanics. He talked about just what it was that first starting his thinking about sagittal plane facilitation theory mechanics in the context of ‘functional hallux limitus’ and what that is and how that influenced his practice over the last three decades. Howard regularly teaches and lectures on the concept of sagittal place biomechanics in many different countries since his retirement from clinical practice.