Kinesiology of Athletic Movement: Kicking Zahra Abdalla Ayan Elmi Elizabeth Jenket Alejandro Morales Sondos Serageldin Jill Sutera Kevin Weeks
Background of Kicking • Kicking: A series of rotational movements. • The Aim: to produce through the kinematic chain of body segments, high angular velocity to the foot in order to exert enough force for the ball to move. • Kicking is a complex motor task, which rapidly develops between the ages of four and six.
Goal of Kicking • The “place kick” action is performed in order to accomplish a certain velocity of the ball ( needs greater swing limb/foot speed), or to direct the ball to a desired location. • The direction of the ball is determined by the position of the planted foot and the hip position at impact. • The length of time of the kick depends on the approach distance. • The intensity of the kick is determined by the desired distance and speed.
1) You put the foot back in order to gain enough kinetic energy before you hit the ball so the ball will move due to the kinetic energy of the foot 2) Work is done by the foot on the ball- you have to work against gravity (muscles have to exert a torque against the gravity torque) 3) Release Phase: torque due to gravity will change gravitational potential energy of the leg to kinetic energy thus transferring energy from the foot to the ball Biomechanical Analysis of Kicking Figure 3. The last step and kicking phase in a maximal kick (Luhtanen 1984)
Athletic Application of Kicking • The standing “place-kick” can be applied to soccer and point scoring in both rugby and football. • This kick action can be broken down into 6 stages: - the approach - plant-foot forces - swing-limb loading - hip flexion and knee extension - foot contact - follow-through
Kicking Application cont. • The Approach: As a child develops their kicking pattern they learn to pace the run up and adjust their approach into a diagonal angle. A 45-degree angle produces the greatest peak ball velocity. • Plant-foot Forces: The ground reaction force on the plant foot directly affects the ball speed. There is also a direct relationship between the direction of the plant foot and the direction the ball travels. The most accurate direction of the ball can be accomplished when the foot plant position is perpendicular to a line through the center of the ball. The optimal anterior-posterior (A-P) position of the plant foot is adjacent to the ball. This A-P position determines the flight path of the kicked ball.
Kicking Application cont. • Swing-limb loading: The swinging of the limb prepares for the descending motion towards the ball. During this phase the opposite arm is raised to counter balance the rotating body. Both arms help keep the center of gravity over the support foot and increases the moment of inertia of the trunk. The kicking leg is extended and the knee is flexed to store elastic energy and allow a greater transfer of force to the ball. At the end of this phase there is maximal eccentric activity in the knee extensors. • Hip flexion and knee extension: In this phase the thigh is swung forward and downward with a forward rotation of the lower leg. The leg then begins to accelerate due to the combined effect of the transfer of momentum and release of stored elastic energy in the knee extensors. The knee extensors then powerfully contract to swing the leg and foot towards the ball. After the kicking leg makes contact with the ball the knee is extended and the foot is plantarflexed. At this time the hamstrings are maximally activte to slow the leg’s eccentric movement.
Kicking Application cont. • Foot contact with the ball: When the foot makes contact with the ball 15 % of the kinetic energy of the swinging limb is transferred to the ball and the rest of the energy is used by the eccentric activity of the hamstring muscle group to slow the limb down. • Follow –Through: This serves to keep the foot in contact with the ball to maximize the transfer of momentum and therefore increase speed. This also serves to guard against injury by gradually dissipating the kinetic and elastic forces.
AGONISTS and ANTAGONISTS • Agonists: • Hip flexors: rectus femoris, iliopsoas, sartorius • Knee extensors: 4 • Dorsiflexors • Antagonists: • Hamstrings • Gastrocnemius • Plantarflexors
SYNERGISTS and STABILIZERS • Synergists: • Hip: internal & external rotators, adductors, abductors • Knee: adductors, abductors • Ankle: Peroneals (lateral) , post tibialis (medial) • Stabilizers: • Trunk stabilizers: Abdominals, psoas major, erector spinae and postural muscles • Muscles of the plant foot and leg
Neutralizers andPrimary Muscle Group IMAs & EMAs • Neutralizers: • Hip abductors and adductors, internal and external rotators • Foot inverters and everters, pronators and supinators • Primary Muscle Group IMA & EMAs: • Hip flexors, knee extensors, dorsiflexors of tailor joint
Major Muscles Contractors • Adductor Magnus • Pelvic on femoral adduction • Support body weight • Pectineus, Adductor Breves & Longus • Femoral on pelvic adduction torque • Accelerate the ball • Hamstrings & Quadriceps • Flexion &Extension • Creates force
Axis of Rotation of the Hip Saggital, Frontal and Horizontal Plane
Axis of Rotation of the Knee Flexion & Extension in the Sagittal Plane
Axis of Rotation of the Knee Horizontal Plane
Major External Forces • Gravity, friction, and time (duration of contact) • The ball will exert a force equal in magnitude to contact but opposite in direction
Major Internal Forces • The movements in soccer are monitored by players internally. Sense organs within the muscles, joints and tendons provide information to the central processing system about their movements. This is commonly called muscle sense or kinesthetic sense. In the internal loop the nerve endings in skin tell the footballer about the touch of the ball, kinesthetic receptors in joints control the joint angle, muscle spindles relate to the length change in the muscle, and the Golgi apparatus the tension in tendon. • Internal force phases of kick include: preparation, approach & kick, and follow-through.
Radius of Gyration The radius of gyration is the distance between the hip of the planted leg and the opposing hip is the axis of rotation of the kicking motion.
The length of the body segments or the radius of rotational movements influences the linear velocity of the rotating foot. The linear velocity of rotating levers can be expressed as a product of the radius of rotational movement and angular velocity. A skillful soccer player produces high ball velocity by maximizing angular velocities of the thigh and shank (Asami et al. 1976). Linear and Angular Velocity
Torque: exerted by the muscles to rotate the lower leg around the knee joint in order to move the lower leg in position to kick the ball Torque due to gravity: knowing the line of action of the weight (perpendicular distance to the line of action of the weight of the leg) Note: When you try to kick the ball, kick it at the center of mass- force from the foot should hit it in the center of mass to achieve total translational energy so the ball can reach farther, yet if not achieved it will be more stable Torques and Center of Mass http://www.bethpage.ws/admin/chiscock/Kicking_Ball.jpg Figure 8. Torque of hip, knee and ankle in a maximal instep kick (Luhtanen 1988)
1st Law: A body continues in a state of rest or uniform rotation about its axis unless acted upon by an external torque. 1) Rotatory motion of a lever usually results when muscle pulls on bone, providing the external resistance is less than the amount of muscular force acting on the bone. 2) If the mass is concentrated farther away from the axis of rotation, the moment of inertia will be greater, thus the system (i.e., lever) will be harder to start or stop. 3) The mass distribution about an axis of rotation (i.e., joint) may be altered by changing the limb position. Newton’s Laws and Angular Motion: Newton’s 1st Law
2nd Law: The acceleration of a rotating body is directly proportional to the force causing it, in the same direction of the force and is inversely proportional to the moment of inertia/ mass of the body. Work=Force x Distance: the magnitude of force applied by the kicker against the ball and the distance the ball moves in direction of the force of the kick Angular momentum of a limb is increased if the angular velocity is increased ex. kicking a ball Acceleration of the Ball= Force Contact/ Mass of Ball Reactive Forces Foot hits the ball: force applied on the ball (contact force) and ball exerts reactive force back which gives rise to the acceleration of the ball Newton’s Laws and Angular Motion: Newton’s 2nd Law Figure 5. Vertical, horizontal and lateral ground reaction forces during maximal kicking (Luhtanen 1984)
When the foot touches the ball an impulse is exerted by the contact force of the foot I= Force contact x Time (duration of contact) P= Impulse (P= change in momentum of the ball) The momentum of the kicking foot and leg= mass of the leg + velocity of the foot at impact + velocity of the body as the player approaches the ball. If you want to give the ball higher momentum your impulse must be higher. The greater the mass of the leg, and the greater the velocity of the foot at impact, the greater the resultant velocity of the ball at impact. Newton’s 2nd Law: Impulse-Momentum http://home.flash.net/~waynok/graphics/flyingthroughtheair.jpg
The velocity production of the ball can be evaluated according to the conservation of the linear momentum in collision. The action of the ankle can increase the release velocity of the ball a little. Through elastic collision, linear momentum transfers partly to the ball. The bigger the leg mass the higher the ball velocity. The point of application must be inside the effective hitting area, which depends on the tension in the ankle. Impulse-Momentum Continued…
When a torque is applied by one body to another, the second body will exert an equal and opposite torque on the other body. F=ma; the kicker and the ball experience different acceleration effect, that is dependent on its mass Acceleration of the Ball= Force Contact/ Mass of Ball So the ball will exert a force equal in magnitude to contact but opposite in direction Newton’s Laws and Angular Motion: Newton’s 3rd Law http://www.shetland.gov.uk/community/news/images/j0400097.jpg
The acceleration of the kicking leg, and the resultant velocity at impact, is determined by the muscle forces being applied by the kicker. The release velocity of the ball with respect to timing had the strongest relationship to the maximal torque produced during the 1. hip flexion 2. knee extension and 3. short ankle stabilizing in the kicking leg. Thus the increase of the body mass means increase in the mass of the foot and this automatically increases the release velocity of the ball in the kick. The regulation of the effective mass in the kicking foot might play an important role for getting the high release velocity to the ball (Luhtanen 1988). Acceleration and Velocity
The role of the arms in kicking is primarily to maintain the balance of the body. The arms are usually extended out to the sides of the body during the forward motion of the kicking leg, to help to keep the center of gravity over the support foot, and to increase the moment of inertia of the trunk and increase resistance to rotation around the spine, or the long axis of the body. As the kicking foot contacts the ball, the opposite arm moves forward and upward across the body to help keep the trunk down and the body in balance. The Role of the Arms http://students.umf.maine.edu/~pullenam/soccer.jpg
Kicking Questions • What are the primary movers (agonists) involved in the swing phase of kicking? a) Quadriceps, hamstrings, plantar flexors b) Hamstrings only c) Gluteus medius, soleus, tibialis anterior d) Adductor magnus, soleus, fibularis longus,sartorius • The greater the mass of the leg, the______ the velocity of the foot at impact, • the ________ the resultant velocity of the ball at impact. a) greater, lower b) lower, greater c) lower, lower d) greater, greater • The momentum of a soccer kick is dependent on: a) The velocity of the kick b) The mass of the ball itself c) The duration of the impact between the foot and the ball d) All of the above • What is the purpose of the arms during kicking? a) To allow greater transfer of force to the ball b) To increase the intensity of the kick c) To counter balance the rotating body d) To increase speed • How is Newton’s third law applied to the motion of kicking? a) Work= Force x Time b) The ball will exert a force equal in magnitude, during contact, but opposite in direction. c) The length of body segments influence the linear velocity of the rotating foot. d) When the foot touches the ball an impulse is exerted by contact forces of the foot.
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