This is a video from their website which has a few redeeming qualities and teaching value.
1st of all, we notice that the shoe is rockered in the saggital (:02-:05 and :49-:54) AND coronal (:55-:59) planes. Rockers in the saggital plane are a Godsend for folks with hallux limitus and functional hallux limitus (limited ablility to dorsiflex the great toe, aka Turf Toe). Rockers in the coronal plane (the side to side motion plane) promote medial/lateral instability. This can be therapeutic, but ONLY if you have earned the right (through skill, endurance, strength) to be able to handle that instability. Challenges to the coronal plane, sometimes referred to as the lateral plane, are helpful in rehabilitating things like ankle sprains. Rockers, in general, have a higher metabolic cost and require greater proprioception and skill to handle, thus the “increased muscle activation” (1:12-1:23).
A saggital rocker can decrease stress on the knees and hips (1:27-1:30) because it limits the amount of ankle dorsiflexion needed and the “rolling” motion assists in knee and hip flexion. This increased motion comes at a cost of increased hamstring activation (1:15-1:17) and a smaller increase in gluteal activation (1:18-1:20). Do we really want to promote the hamstring dominance when the gluteus medius-maximus team is supposed to help carry us through the gait cycle? Remember, the Gluteus Maximus is only supposed to contract up to the moment before midstance, with a burst at toe off.
It would be interesting to see what effect (positive or negative), or if any, they have on foot intrinsic activity. With a rigid last (you cannot bend these shoes because of the rigid built-in rocker) the foot may be pretty silent since the shoe merely passively rocks you forward into each step.
On a positive note, they do promote a more upright posture (:18-:27) compared to a traditional heeled shoe which purchases the user forward as noted in the video. The shoes also have a decreased amplitude of vertical oscillation (:19-:22).
We again caution that need to “earn” you way into this shoe, and though it can be a rehab tool, we do not feel it is a great shoe for day to day activities or running in. One of our greatest concerns, other than what the shoe can be doing to the normal function of the foot muscles and joints, is the extremely soft crash-entry zone at the rear 1/3rd of the shoe (depicted here in red in the video). The EVA foam is so soft that a heel strike cannot be achieved. Heel strike is part of normal gait. However, as we have coined, there is a difference between heel strike/impact and heel contact. We recommend the thought of the heel “kissing” the ground and smoothly transitioning to midfoot strike, no matter what shoe is used in walking. Certainly running is a different matter, we prefer midfoot strike, where the foot type is accomodating so such a strike. Not everyone has a foot type that will respond to a forefoot strike (ie. forefoot varus) without eventual pathology or injury. If heel strike were to occur in the MBT the risk of knee hyperextension would be on the table and retrograde knee motion is never good and never helpful when progression forward is desired.
Almost every shoe has a perk and a drawback. You just need to understand the engineering of the shoe and understand the foot and body that is going into the shoe, to decide how it might help you. We do use this shoe for some foot types, mostly as a therapeutic device to help someone heal or improve skills to achieve performance success. But as a day to day shoe, this is not a shoe we ever recommend. This shoe alters normal biomechanical events, a compensated gait if you will.
The Gait Guys: just the facts, so you can make more educated decisions.