The foot is designed to strike the ground, dissipate the bodies weight as it strikes, the structure is designed to “give” and pronate/flatten in order to shock absorb. Then as one rolls forwards with the body over the foot one goes onto the toes and so causes a bend at the big toe joint. This bend then tightens the spring ligament under the arch of the foot and so creates tension in the sole of the foot, which stabilises the structure and of the foot and also tensions the ankle joint, which in turn creates an external rotation in the lower limb. The rotation stabilises the knee and the stabilisation journeys up the leg to the hip and so creates a better support to the pelvis and lower back.
When one is bare foot or in normal shoes that are tied/attached to the feet, this method and the above system falls into place.
When one wears shoes such as Flip flops or Ugg boots the shoe is slopping around on the foot. Several things happen:
1.The foot “claws” in order to hold the shoe on. This firstly causes a raise in the forefoot which can lead to calluses on the top
of the foot and sores under the mid foot. It causes stress on the end of the bone that are designed to lie flat to the floor not at an angle into the ground.
Due to the forefoot arch there is no way that the big toe joint can work as it is designed. So tension is lost in the spring ligament, under the arch of the foot and there is no support to the knee from the ground up. The problem with this is the knee gets worn and tired and unstable from constant walking with no structure from below.
2. The second thing that happens is that often the shoes have no grip on the sole and are slippery so to avoid the foot sliding in the shoe the feet start to turn out like “a duck”. When this happens the ankle often collapse in and the foot flattens, because the push off in the gait no longer comes across the foot and off of the big toe, but it comes from the sideways push off the inside edge of the ball of the foot. The spring ligament cannot be tensioned and so the ankle become lax and the knee is not stabilised either, because when walking there is no bend in the big toe joint.
So the argument that flip flops are closer to being bare foot than shoes is nonsense. They cause the foot to work in an incredibly dysfunctional way which is detrimental to the knee and hip and lower back.
The foot is designed to be used straight on. Toes pointing forwards, so that the ligaments can work correctly. When this is done the hip stabilising muscles – the gluteus muscles will activate and then control the knee from above and so the leg functions correctly and injury is avoided.
The discussion about shoes versus bare feet – is a different one. Shoes do inherently have a heel. The problem with a heel is this causes a shortening in the calf muscle and will by the nature of lengthening the back edge of the leg make it easier to heel strike. The conversation here is then about landing on a jarring straight leg. This is not what my conversation is about. My conversation is about making sure the big toe can work properly and so trigger the spring ligament and look after the knee. Years of walking with toes out and slumping into the hips will cause a weakness in the ankle and so a weakness in the knee. Toes turned out means upper leg is turned out – which means it is wearing incorrectly in the hip joint as well. So if the person is not into exercise and correction it would be much more advisable to wear decent shoes to protect the leg and hip joints.