Page 1
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
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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
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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/
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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)
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Common movement patterns (Table J.1, p 336)
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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
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Three-segment kinetic link model
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Three-segment model: (Fig j.2, p 339)
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Whip-like action of segmental system
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Three-segment model when airborne:
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Throwing motion (sequential)
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Segmental sequence when throwing
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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.
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Javelin – similarTo baseball pitch
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Shotput – some throw & some push
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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
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Development of throwing motion