Introduction to Kicking

The mature form of the kicking skill has been characterized by an approach to the ball of one or more strides with the final stride being that of a jump, step or lunge. The placement of the supporting foot is at the side, and slightly behind the stationary ball. The kicking leg is first taken backwards and the leg flexes at the knee (called leg cocking). The motion of the swing leg initiates an action-reaction of the opposite arm (Newton’s third law of motion: if a body exerts a force on another, there is an equal and opposite force, called a reaction on the first body by the second). Forward motion is initiated by rotating the pelvis around the vertical axis (the supporting leg) and by bringing the thigh of the kicking leg forwards while the knee continues to extend. Once this initial action has taken place, the thigh begins to decelerate until it is essentially motionless at ball contact and the action-reaction causes the opposite arm to the kicking leg to reverse their rotations around its vertical axis. During this deceleration, the shank vigorously extends about the knee to almost full extension at ball contact the leg remains straight through ball contact and begins to extend during the long follow-through. The foot often reaches above the level of the hip during the follow-through and a final jump or hop can be seen when conservation of momentum continues past its point of impact.

Abstact:Introduction to impact force and muscle turning

Researcher's such as Dekel and Weissman, 1978; Radin et al., 1973, 1978 and Serink et al., 1977) state that If the joints are regularly submitted to such high-frequency impact force peaks, subchondral bone and articular cartilage begin to degenerate with speculation that these ‘impact force peaks’ are the causative factors in the development of lower back pain and running injuries in runners (Clement et al., 1981; James et al., 1978).

In an attempt to minimise these impact forces, changing the foot and leg geometry along with ankle and knee joint stiffness have been described by Lafortune, Hennig and Lake (1995) as being important developmentally both individually as well as collectively. Nigg (1997) suggested that the strategy of changing the coupling between the soft and rigid structures of the individuals’ leg termed ''Muscle Tuning'', may also be of much importance.

Nigg (1997) spoke of the muscle turning as a concept suggesting that the impact forces during heel strike should be considered as an input signal, characterized by amplitude and frequency. This impact force signal could produce bone vibrations at high frequencies and soft tissue vibrations of the human leg (e.g., triceps surae, quadriceps, or hamstrings muscles) at frequencies that might concur with the frequencies of the input signal.

Abstract on windlass mechanics

It is during the action of dorsiflexion of the toes, which occurs in late stance phase that the plantar aponeurosis is stretched as it wraps around the metatarsal heads. This is the so-called windlass mechanism. Windlass is the tightening of a rope or cable (Viel and Esnault, 1989), which according to Hicks (1954) is like a triangular structure or truss, which occurs in the late phase of stance. This windlass is responsible for the stretch tension from the plantar fascia preventing the spreading of the calcaneus and the metatarsals and maintainsing the medial longitudinal arch (Fuller, 2000), which contributes to stiffening of the foot by pulling on the heel, causing inversion at the subtalar joint and `locking' the midtarsal joint (Briggs and Tansey, 2001). This occurs by shortening the distance between the calcaneus and metatarsals with the plantar fascia forming the tie-rod that runs from the calcaneus to the phalanges via the midtarsal joint, which carries as much as 14% of the total load on the foot whilst lowering the arch degenerates the load bearing capacity of the foot (Kim and  Voloshin,1985).

Abstract on the proximal to distal sequencing

There are currently two explanations for the proximal-to-distal sequence, both based on the principle of conservation of angular momentum. Theory One ''external moment'' states that once the motion of the system begins, an angular momentum is developed in the system and the distal segment lags behind. As the proximal segment approaches maximum velocity, an external force opposes this motion, which negatively accelerates the proximal segment, allowing inertia to propel the distal segment forward (Ford, 1998; Marshal and Elliott, 1999). Theory Two '' internal moment'' contends that no external torque is applied to the system after the initial acceleration of the system takes place. The system with some mass, is said to move with a given angular velocity, thus having an angular momentum, which is conserved throughout the action (Putnam ,1983: Ford, 1998).

However, these theorys may not  tell the full story and may infact only explain partial representation.