The forefoot is essential in making humans capable of standing upright and walking. The forefoot is the balance lever made up of the metatarsals and toes exerting pressure against the ground, making this possible.
The metatarsals counteract ground forces
The metatarsals and phalanges (toe bones) allows us to stand and move without falling from loss of balance. The equivalent to standing without the aid of your forefoot is to stand on stilts. All balancing is now accomplished by your upper body creating a balancing momentum by transferring weight front to back and side to side. Without the forefoot we would be unable to move with grace, agility and power.
The muscles controlling the metatarsals
The muscles controlling the metatarsals, located in the feet and lower legs, are instinctively designed to counter act ground forces. The more you lean your upper body forward, the harder these metatarsals press against the ground. That is the way the brain is programmed to respond. Conversely, if you are about to fall backwards, your whole foot and toes are instinctively pulled up even though it has absolutely no practical consequence. It is just another piece of information confirming the natural muscle responseof the metatarsals. When falling backwards, they are trying to reduce the pressure against the ground in an attempt to stabilize your balance.
If the first metatarsal is not on the ground, experiencing ground forces, the muscles have no reason to and will not generate a counter force by flexing. The muscles will not activate unless done consciously by will or subconsciously by pressure being felt underneath the metatarsals – ground forces. Not until the ground force pressure passes a threshold will the muscles contract to create a counter force. The metatarsals pressing back against the ground.
The first metatarsal
The first metatarsal in particular is vital to proper gait, balance and body posture. If the first metatarsal does not become weight bearing until very late in the contact gait cycle, it does not establish positive ground contact, and as a result weight bearing shifts to the second metatarsal which is a very typical gait pattern.
Loss of first metatarsal weight bearing
When body weight is mainly carried by the second metatarsal, the foot is unstable similar to wearing ice skates. All the calf muscles engaged in stabilizing the ankle becomes hyper active and muscles throughout the body is activated to stabilize the unstable body. This is the source of typical muscle overuse pain from head to toe. As the muscles tire and weaken with age, body mechanics becomes more distorted creating increased stress on the joints from misalignment. This is the source of most joint pain and early osteoarthritis.
Elevated versus hyper mobile
Many people are told by their foot doctor that they have hyper mobility of the first metatarsal which was sighted by Dr. Dudley Morton as part of the syndrome later named after him - Morton's Foot Syndrome, also called Morton's Toe. The first metatarsal is short relative to the second, and hyper mobile as in moving upwards without resistance. This raises two questions. 1] Why would hyper mobility only involve the first metatarsal and not the other metatarsals, or for that matter other parts of the foot and body? 2] Why would the muscles not respond to the ground forces if felt? Even though hyper mobile, the metatarsal should be on the ground. One could presume that because the metatarsal was hyper mobile, insufficient ground forces would develop. I.E. the threshold for activating the flexor muscles would not be reached until the motion limit of the first metatarsal would be reached, very late I the weight bearing cycle. Posture Dynamics have proposed a different theory, that the first metatarsal is elevated. This can be clearly displayed by performing a knee bend while forcing the middle of the knees to travel in alignment over the middle of the feet as they should. As can be seen using a pressure plate, the first metatarsals are not on the ground and bearing weight. Not until the knees are released to move medially (toward the mid-line of the body), will the first metatarsal reach the ground, become weight bearing and begin to support the body.
Restoring ground contact for the first metatarsal
Placing a small wedge underneath the first metatarsal and big toe will restore ground force input to the first metatarsal. The small wedge does not support the metatarsal, it merely changes the timing at which the first metatarsal senses sufficient ground forces to activate the muscles that push the first metatarsal to the ground. As the body continues forward during gait and the heel lifts off the ground, increased pressure builds underneath the first metatarsal which in turn increases the counter pressure generated by the muscles controlling the metatarsals.
When the first metatarsal is engaged and properly weight bearing, the forefoot is balanced, meaning the foot becomes laterally balanced. The ice skate has effectively been replaced by a tripod. At this point, the feet are able to fully support and balance the body so 1] all the postural muscles relax, and 2] the joints are maintained in better alignment so they are not being torqued and unevenly loaded.
Can arch supports achieve this balance?
An arch support can balance your feet to a degree while standing still, but an arch support will not bring your first metatarsal to the ground, and especially after the heel rises in gait, the weight will again be transferred to the second metatarsal and destabilize foot unless the arch is so severe it pushes your feet to a lateral toe off.