Sport biomechanics – outline

• Reading assignments:– Kreighbaum & Barthels – Module J (pp 335-

353, Ch 11 (pp 370-384), esp pp 372-375 on baseball pitch

– Adrian – Ch 17, esp pp 333-339, 352-356– Review article on throwing and injuries– Review article on overweight and underweight

baseballs

Biomechanical correlates of participation in sports: Areas of interest, effort, & potential

contributions• Evaluate process - technique• Injury potential/prevention• How to enhance acquisition – motor learning• Design appropriate conditioning programs to

enhance performance• Equipment Design and Selection

– ground-foot interfaces – protective equipment (pads, gloves, head gear)– striking implements– balls

Exercise and Sport Biom Prof Org • American College of Sports Medicine• International Society of Biomechanics• International Society of Biomechanics in Sports

North American Society of Biomechanics• Website: biomechanics worldwide

– http://www.per.ualberta.ca/biomechanics/

Throwlike and Pushlike Movement Patterns• Usual objectives of throw and push patterns

• projection of objects for greatest horiz or vert dist – ex : javelin, discus, shotput

• projection of objects for accuracy with speed a factor– ex: volleyball, tennis, racquetball, baseball pitch

• Movement pattern terminology review• Throwing patterns are further defined as underarm, sidearm, or overarm

(see Table J.1, p 336)• Skills listed under each pattern differ because of constraints

– ex: rules governing implement or ball, rules governing target.

• Open and Closed chain movements• Open kinetic chain - sequential segmental action, end segment is free to

move (e.g., baseball pitch)• Closed kinetic chain - simultaneous end segment movement, end segment

meets with “considerable resistance “ (e.g., shot put)

Common movement patterns (Table J.1, p 336)

Throwlike and Pushlike Movement Patterns (2)• Characteristics of throw-like patterns

– can be a strike or a kick– high end-point velocity is critical– sequential segmental action, object lags behind elbow and/or shoulder

• Open kinetic link model - Figure J.1, p 338; J.2, p 339• Linear motion of a point on a rotating segment: V = r• Sequencing segmental rotations - kinetic link principle

– system has a base and a free open end– segmental masses progressively decrease– an external torque is applied at the base to initiate the movement– segmental rotational acceleration is timed sequentially

• A model of an open kinetic link system - Fig J.4, p 343• Throwlike movements performed while in the air - Fig J.5, p 345

Three-segment kinetic link model

Three-segment model: (Fig j.2, p 339)

Whip-like action of segmental system

Three-segment model when airborne:

Throwing motion (sequential)

Segmental sequence when throwing

Phases of pitching:1. Windup (a-k)2. Early Preparation (l-m)3. Late preparation (n-p)4. Release (r-u)

From: Feltner, M. & Dapena,J. (1986) Dynamics of shoulder and elbow joints ofthe throwing arm during a baseball pitch. Int J Biomech235-259.

Javelin – similarTo baseball pitch

Shotput – some throw & some push

Throwlike and Pushlike Movements (3)• Pushlike patterns - Simultaneous segmental actions

– Objective is accuracy, or large motive force– Distal segments move simultaneously, resulting in rectilinear

movement of distal segment– Four differences in throw and push (p 350). In throws:

• distal segment “lags back”, segments move sequentially, object moves curvilinearly, wheel-axle movements (shoulder and hip rotation) involved

• Movements lie on a throw-push continuum, the location depending on constraints of performer and object:– performer strength and skill– object mass, size, and shape

Pushing Motions

Development of throwing motion