Biomechanical analysis of the role of shoe inserts for over pronated foot during running

Gait is the more specific way of locomotion of the lower limb. Human bipedal gait can be distinguished in 3 different tasks: walk, run, and hop. Walking is characterized by a double limb support phase, while running has only single limb support and a swing phase of the not supporting-leg. Both of them are the states of a dynamic equilibrium in which the person has to control his posture in order to not fall. Gait cycle is primarily divided into 2 phases: stance phase and swing phase. The stance phase starts with the initial contact of the foot with the ground (heel strike), then the leg increases the loading on the foot as the foot comes down, until it leans completely on the ground (mid-stance). The second part of the stance phase changes the loading from the rear foot to the forefoot and the heel is lifted (heel off). Finally the terminal stance (push off) is characterized by the toes pushing against the ground to give a propulsion to the body. The swing is divided as well in 3 components, the initial swing (acceleration phase), midswing, terminal swing (deceleration phase). The stance initial contact phase is characterized by energy absorption while the swing push-off phase is the time of energy release. The stance phase is 40% of the gait cycle in running while in walking it is 60%. During Gait Cycle there are 4 mechanism of energy transfer:

-Pendulum: swing leg

-Joint force transfer: the energy transfer from one body segment to another (change the direction of movement)

- Whip: early swing and end of swing

-Tendon: store elastic energy. One joint muscles can transfer energy from one segment to another , two joint muscles can also transfer energy from one joint to another.