Transcript ss20
THROW Pattern PUSH Pattern proximal segments in front of projectile with distal segments behind projectile all segments behind projectile pushing the projectile or load sequential for simultaneous for v curvilinear path mostly wheel-axle F rectilinear path mostly lever motions Movement Patterns - Related Skills Underarm Sidearm Overarm Kick Badminton Bowling Hockey Horseshoes Volleyball Baseball Discus Hammer Handball Squash Tennis Volleyball Badminton Baseball Cricket Javelin Tennis Volleyball Football Rugby Soccer Swimming Constraints: Throw/Push Continuum Mass of projectile Volume/Size of projectile Shape/Profile of projectile Target Area for projectile Strength/Power of person Skill of person OPEN Kinetic Chain CLOSED Kinetic Chain • Throw or Kick • Jump or Push or Pull • End Segment Free [e.g. hand, foot] • End Segment Restrained [e.g. foot, hand] • sequential movement of body segments • simultaneous movement of body segments Throwlike Patterns • 1. Proximal Parts Move First • 2. Distal Parts Lag Behind • 3. Achieve either : maximum distance [ HORZ or VERT ] OR maximum velocity compare the positions of the pinstripes in hip region versus shoulder region FIG 7.4 Page 233 magnitude of Radius influenced by Mass of object Note position of shoulders relative to hips in each photo Shoulder Medial Rotation Axle > Upper Arm Shld to Elbow Wheel > Forearm Arm/Racquet Elbow Extension during final phase of Shoulder Medial Rotation Fig J.1 page 338 1. segment A is accelerated which gives L to entire system: segments A, B, and C 2. A rotates cw while B and C lag behind 3. A is THEN decelerated by muscle T 4. To conserve L, B accelerates cw THEN decelerates, C then accelerates cw transfer L to arm by reducing/stopping L in shoulders End Point v due to decreasing • See FIG. J.1 on page 338 r L= mk² x • initial k is from axis “a” to top of segment C • when segment A decelerates, the k changes to the distance from axis “b” to top of segment C • when segment B decelerates, the k changes to the distance from axis “c” to top of segment C v=r • final velocity of hand or foot or implement @ release/impact determines projectile v • r = d from the axis of rotation [e.g. joint] and the contact point of release/impact • see FIG J.12 on page 352 with regard to r Kinetic Link Characteristics • system of linked segments with a fixed base and a free open end • more massive segments @ proximal end • least massive segments @ distal end • initial motion caused by T applied to base • T gives entire system L L= mk² x OR L = I Sequential Motions • 1. proximal/massive segments move first giving L to entire system • 2. external T decelerates proximal segments • 3. to conserve L, next segment, which is less massive, accelerates with rotation now occurring about a new axis and a smaller k • 4. Each successive segment/link accelerates achieving than previous segment due to both m and k getting progressively smaller Airborne Reaction Rotation while airborne, if a person initiates rotation about any axis, a reaction rotation will occur in the opposite direction about that same axis due to the law of conservation of angular momentum turntable demo Minimizing Airborne Reaction Rotation VB spiker abducts hip and/or flexes knees to I (I = mk²) in lower extremities Note: Reaction Rotation in upper body of the kicker Lever Motions • Flexion/Extension Wheel-Axle • Medial/Lateral Rotate • Protraction/Retraction • Pronate/Supinate • Abduction/Adduction • Inversion/Eversion example of one of the wheel-axle mechanisms in kicking Wheel-Axle Motions • muscle T rotates a bone which becomes an axle • the wheel is the adjacent segment positioned at an angle to the axle • the wheel r (radius) is modified via flexion/extension or adduction/abduction Small Wheel Big Wheel THROW / PUSH for Speed and Accuracy FIG J.8 page 349 FIG J.10 page 350