Hip Flexion In Kicking Motion - Essay Example

Hip Flexion Kicking movement in football is a relatively easy series of rotational movements. During the kicking movement, the leg functions as an open kinetic chain. The motion pattern of kicking is generally accepted as a proximal-to-distal sequence of segmental motions in which the proximal segment (the thigh) initiates the movement, causing the more distal segment (shank and foot) to lag behind, followed by a deceleration of the proximal segment and an acceleration of the more distal segment just before impact (Lees, 1996; Lees and Nolan, 1998). During the kicking movement, the segments of the kicking leg move by rotating about an imaginary axis of rotation that passes through the proximal joint of the segment. The motion of rotating body segments in kicking can be described in terms of angular position, velocity and acceleration. The linear velocity of the centre of mass of the rotating foot hitting the ball is directly proportional to the product of the angular velocity and the radius of rotation of the consecutive body segments and the linear velocity of the hip joint. The timing of these rotational movements is important for the impact of the foot with the ball. Putnam (1983) used the time between peak angular velocity of the thigh until the beginning of knee extension as a measure of timing during kicking with the preferred leg. Luhtanen (1988) used the interval between the shank reaching maximum angular velocity and impact as a measure of timing (Simonsen, E.B., 2002). The acceleration of the kicking leg, in addition to the resulting velocity at impact, is concluded by the muscle forces being applied by the kicker. It has been accounted that the speed of the ball at impact was directly proportional to the calculated strength of his themes. The release velocity of the ball in regards to its timing had the strongest relationship to the maximal torque formed during the i. hip flexion, ii. Knee extension and iii. Short ankle alleviating in the kicking leg. In addition the relationship between the maximal resultant forces of the thigh and shank and the release velocity of the ball was tough. The link between the release velocity of the ball and age was elevated however less than with weight or height. Consequently the augment of the body mass means boost in the mass of the foot and this by design increases the release velocity of the ball in the kick. A significant ability in the game of soccer is the capability to kick the ball powerfully and precisely. The instep kick is the kick which is most frequently used for the utmost force as well as distance, as for a shot on goal or a long pass. The force for the long kick is put on from the run-up into the ball, and from the movements of a maximum number of body parts. These comprise hip and trunk rotation, in addition to hip flexion, knee extension and ankle plantarflexion to shape a rigid surface for impact. The kick with run-up creates longer and more potent kicks than the standing kick. This is due to the augmented momentum of the kicker at impact. If the kicker is moving onward straight at 4 m/s at impact with the ball, this velocity is put in to that imported by the kicking leg as it moves on the hip joint. Nonetheless, some of the horizontal velocity is vanished at the time of positioning the support foot; as the center of gravity must be held up to permit time for the full leg swing of the long kick. Biomechanical analysis of coordination and control of soccer skills Qualitative and quantitative methods have enabled the general characteristics and development of soccer skills such as kicking to be determined. Using qualitative methods has allowed a great deal to be learned about the characteristics of kicking and aspects of coordination and control of the skill. For example, the mature form of the soccer instep kick is characterized by an angled approach to the ball with one or more steps (Lees and Nolan, 1998). The steps leading into the kick increase body and hence foot speed, while the angled approach orientates the body so that the pelvis can rotate through a greater range of motion to ball contact. This orientation also has the effects of tilting the body to one side so as to lift the hip (of the kicking leg) and compensating for the flexion of the support leg, which lowers the body, enabling an appropriate foot-ball contact position. The length of the final step also enables the pelvis to be rotated backward: the longer the step, the greater the range of motion. This action allows the foot to be taken back through a greater distance and hence increases the acceleration path of the foot towards the ball. The forward motion of the kicking leg is initiated in a proximal-to-distal sequence of the thigh and shank following placement of the non-kicking foot. This sequence is prevalent in biomechanical analyses of other dynamic interceptive actions, such as volleyball serving (Luhtanen, 1987). The forward rotation is initiated by pelvic rotation about the hip of the support leg followed almost simultaneously by rotation of the thigh through hip flexion. The knee of the kicking leg continues to flex until it is maximal and then begins to rotate forward as the thigh approaches a vertical orientation. As the shank accelerates forward, the thigh is slowed down. Energy flows from the thigh to the shank and increases its angular velocity. In skilled kicking, the peak linear velocity of the foot is achieved just before contact with the ball. The kicking leg is almost fully extended at ball contact and remains extended throughout the early stages of the follow-through until the end of the follow-through, where the knee begins to flex. These actions enable the foot to reach a high velocity, which is the main determinant of ball velocity. Other factors such as ball mass, effective striking mass of the foot, ball pressure and foot deformability all affect final ball speed (Lees, 1996). Qualitative analysis can be used to identify most of these characteristics of the kicking skill. It has also been used to define the development characteristics of the skill. Wickstrom (1975), in a review of cross-sectional and longitudinal developmental studies of kicking, suggested a four-stage developmental model for children aged 2-6 years. The first stage involved a basic pendular motion of the kicking leg with little knee flexion; the second stage exhibited an increase in the preparatory backswing of the kicking leg through hip extension; the third stage demonstrated greater knee flexion and the fourth stage used pelvic rotation. In a later study, Bloomfield et al. (1979) identified six stages of development for the soccer instep kick in boys aged 2-12 years. The stages are similar to those described by Wickstrom (1975, 1983; see Table 1). In addition, they reported the introduction of a run-up in the fourth stage and an angled approach in the sixth stage to define the full mature form of the skill in which coordinated hip hyper-extension and knee flexion during the backswing were demonstrated. It appears that the main features of the kicking skill can be developed in some individuals by the age of 6 years. This finding has implications for talent identification and skill development. It is worth noting that these largely qualitative analyses have clearly identified features of the kick, such as angled approach, tilt of the trunk and pelvis, which demand a full three-dimensional analysis of the movement. Table 1. Framework for analysis of development of coordination in the mature kicking pattern (Wickstrom, 1983) (a) Developmental sequence of Characteristics of coordination and timing kicking action in the motor system Phase 1 Preparatory forward step on the support leg to rotate pelvis backward on the opposite side and to extend the thigh of the kicking leg Phase 2 Forward pelvic rotation and swing of the kicking leg with simultaneous flexion at the hip and at the knee Phase 3 Vigorous extension of the lower part of the kicking leg Phase 4 Momentary slow-down or cessation of thigh flexion as the lower leg whips into extension just before the foot contacts the ball Phase 5 Forward swing of the opposite arm in reaction to the vigorous action of the kicking leg (a) Note how more biomechanical degrees of freedom are brought into play as skill develops, and how skilled kicking involves taking advantage of existing forces through precise coordination of the relative timing of action sub-components (Burwitz, L., 2000). Using quantitative methods, typically the position of joint centers in two- or three-dimensional space provides the source data, from which various temporal, linear and angular displacement, velocity and acceleration variables are computed. In particular, quantitative analyses methods can provide the means whereby the coordination and control of a movement can be investigated. Most quantitative methods have been conducted using two-dimensional methods (see Lees and Nolan, 1998, for a review). The reason for this feature of the data is largely technological, as three-dimensional analysis methods have only recently become commonplace. Lees and Nolan (in press) briefly reviewed the three-dimensional studies in the literature; of the five reported, only two contained data on the genuine three-dimensional aspects of the kick (i.e. pelvic rotation) as described above, and which might be influential in terms of coordination and control. This gap in existing research signifies that the information used to explain coordination and control of the kicking skill is limited and incomplete. The two-dimensional kinematics characteristics of the skill are largely defined by the linear and angular data associated with the foot, shank and thigh of the kicking leg. There are extensive normative data for the magnitude of these variables in the literature. However, there is also wide variation in their values for several reasons. These include different standards of skill examined (e.g. collegiate vs. professional players), different experimental task constraints (e.g. the use of a target or not), different variants of the skill (e.g. length of approach), different types of footwear, surface and ball (e.g. boots outdoors vs. trainers indoors) and different standards of physical and psychological preparation during testing. Despite these limitations, some biomechanical investigations have reported data or used analytical methods which have a bearing on the coordination and control of the kicking skill (Burwitz, L., 2000). A significant feature of the soccer kick is the interaction between varieties of muscle groups active in the skill. The agonists bond to start the movement at every of the joints, but these muscles develops into the antagonists to slow the quick angular movements at the joints just before or subsequent to the release of the ball. The hip flexor muscles are leading during the bulk of the swing to the ball. They are at first contracting unconventionally; to stop the legs backswing; then their movement becomes concentric to go faster the thigh towards the ball. Just before the ball contact the hip extensors. The knee flexors rapidly become leading just before the ball contact, acting peculiarly to in fact decrease the rate of knee extension. This is a motivating discovery, as one would expect knee extensor action through contact. But it was found no knee extensor activity just before the ball contact, and in fact the flexors were dominant, peculiarly, causing a decrease in the rate of knee extension. The knee flexors, particularly the hamstring group, may be acting to put off hyperextension and potential damage to the knee. When comparing the muscle movement in the soccer kicks between skilled and less skilled soccer players. Injuries Injuries of the hip, thigh and pelvis are not that common from sport. They may be subtle in presentation and diagnosis is difficult or catastrophic with serious immediate and long -term consequences (e.g. hip fracture or pelvic fracture with shock). The result of a direct blow during contact which varies from mild to severe. Often worse when the muscle is relaxed and occurs in the musculotendinous junction of the Rectus femoris (central position of the quadriceps). In the late swing phase of the gait cycle, hamstrings decelerate the limb. With sudden acceleration from the stabilizing flexion to active extension, strain is put on the hamstring muscles. This injury is most likely to occur with sudden hamstring contraction in athletes when they are cold or have not done adequate stretching. Common situations are at the starting blocks, sprinters at take off, (or high jumpers and long jumpers) a sudden acceleration or resisted extension by football players. The short head of the biceps femoris is most commonly affected. Occasionally dystrophic calcification is seen. Treatment includes rest, ice, compression, elevation and physiotherapy (local cryotherapy and ultrasound). A stretching program is commenced once pain has subsided. Recovery is from days to week (depending upon the severity). The key to treatment is to remedy poor training techniques and improve flexibility. The athlete must carry out an adequate warm-up and stretching program prior to a return to sporting activities. The significant imbalance between quadriceps and hamstrings needs to be overcome and adequate return hamstring strength before returning to sport. A firm elasticized support is useful. Re-injury may occur with longer recovery; therefore exercise good judgment about when to return to sport. www.worldortho.com/oxsportsmed/chapt11.html Reference: Burwitz, L., 2000. Understanding and measuring coordination and control in kicking skills in soccer: Implications for talent identification and skill acquisition. Journal of Sports Sciences. Simonsen, E.B., 2002. Biomechanical differences in soccer kicking with the preferred and the non-preferred leg. Journal of Sports Sciences. Lees, A. (1996). Biomechanics applied to soccer skills. In Science and Soccer (edited by T. Reilly), pp. 123-133. London: E & FN Spon. Lees, A. and Nolan, L. (1998). The biomechanics of soccer: a review. Journal of Sports Sciences, 16, 211-234. Luhtanen, P. (1988). Kinematics and kinetics of maximal instep kicking in junior soccer players. In Science and Football (edited by T. Reilly, A. Lees, K. Davids and W.J. Murphy), pp. 449-455. London: E & FN Spon. Putnam, C.A. (1983). Interaction between segments during a kicking motion. In Biomechanics VIII-B (edited by H. Matsui and K. Kobayashi), pp. 688-694. Champaign, IL: Human Kinetics. Wickstrom, R.L. (1975). Developmental kinesiology. Exercise and Sports Science Reviews, 3, 163-192. Wickstrom, R.L. (1983). Fundamental Motor Patterns, 3rd edn. Philadelphia, PA: Lea & Febiger. www.worldortho.com/oxsportsmed/chapt11.html Read More