What is Biomechanics?• Biomechanics:

– Hall. Basic biomechanics, p. 3“... application of mechanical principles to the study of living

organisms.” and “… use of the tools of mechanics . . . to study the anatomical and functional aspects of living organisms.”

• Biomechanics of human movement:– Kreighbaum & Barthels. Biomechanics: A qualitative study of

human movement , p 1“that area of study wherein the knowledge and methods of mechanics

are applied to the structure and function of the living human system.”

• This course focuses on the biomechanics of human movement

• Good website on biomechanics: Biomechanics world wide Home

The Discipline of Kinesiology

Various types/contexts of human movement

Occupationalbiomechanics

Sport biomechanics

Rehab biomechOrthopedic biom

Sport medicine?

(Aging)

Exercise biom?

Branches of Sports Medicine

D = discipline P = profession

DD

D

D

D

P P

?

P

? ?

Selected practical problems that biomechanics

can help resolve • Exercise biomechanics:

– What is the most effective exercise for the abdominal muscles?– Do you really need an abdominal exercise device? Which type is best?– What types of exercises are effective in promoting bone density?

• Sport biomechanics:– What specific factors should a coach or athlete focus on in order to produce an increase in

performance?– Which mode of exercise is best for producing increased power performance?– Which sport implement or exercise device is best suited for you?– How does the height of the mound affect pitching technique and/or potential for injury?

• What movements and stresses contribute to carpal tunnel syndrome?• Why do you really need an abdominal exercise device? Which type is best

suited for you?

Issues & problems, cont’d• Developmental/aging biomechanics

– Does exercise play a role in promoting bone density or preventing osteoporosis? How?

– Does activity level/type during formative years affect bone density later in life?

– How can we prevent falls in aging people?– What special bone growth/injury problems do we have in youth? (mound

height study)

• Occupational biomechanics (ergonomics):– What movements and stresses contribute to carpal tunnel syndrome?

Low back pain? Shoulder joint impingement?– What is the most efficient, or effective way to do a particular work task?

Problems & issues, cont’d• In what category does each belong?

– How can we prevent decreasing bone density in prolonged micro

gravity environments?– What is the effect of aging on skeletal muscle?– Which type of tennis backhand is best - one-handed or two

handed?– What is the effect of testosterone supplementation on osteporosis?– What is the effect of exercise on bone mineral content in pregnant

women?– What are the ground reaction forces during various types of aerobic

dancing ? Which types are contraindicated for older women?– Biomechanical assessment of knee arthroplasty– Osteoporosis in paraplegics– The scientific basis for closed-kinetic chain exercise after anterior

cruciate ligament reconstruction

General Approaches to Analyzing Biomechanics of Human Movement• Basic approaches to studying human movement

– Kinetic vs Kinematic– Static vs Dynamic– Qualitative vs Quantitative– Maximize, minimize, or optimize

• Factors-Results Approach- a qualitative, heirarchial, deterministic model (Adrian, p 17)– Identify result– List factors that produce the result

• Holistic Principle Approach– Describe the movement– Describe overall performance goal in specific biomechanical terms– Divide movement into phases– Describe purpose/goal of each phase– Identify anatomical, mechanical, and environmental considerations– Determine biomechanical principles for successful performance of each phase and total movement– Assess performance based on these principles

Hay’s heirarchial factors-results analysis model. Each lower factor influences the linked factor above

The Holistic Model: The baseball swing

Holistic Model – the baseball swing

Tools Needed for Biomechanical Analyses

• Prerequisite knowledge– Mathematics– Physics– Anatomy

• Measurement tools– Kinematics – time, space relationships– Kinetics – forces (and their derivatives) and motion

relationships– Electromyography

• Problems, issues, and ideas

Problems for Discussion Mon, Jan 31• Straight-forward, formal quantitative problem involving simple kinematic

equation:– Does the softball or baseball hitter have more time to react to a pitch? Assume that the

baseball pitcher throws to home plate (60.5 ft, or 18.44 m from pitcher’s rubber) at a velocity of 90 mph (40 m/s) and the softball pitcher throws (46 ft, or 14.02 m from pitcher’s rubber) at a velocity of 60 mph (27 m/s).

• More general, complex quantitative problem involving both kinematics and kinetics:– A man fell from the railing of a walkway on a second-story apartment building. He was

found lying unconscious on his back with his center of mass located 5 feet horizontally from a second story walkway and railing. The top of the railing was 21.6 ft above the ground. His blood alcohol content was found to be .30 (inebriated) and he has no memory of how he fell. In order to appraise liability for the accident, we need to determine if the victim walked into the railing or if he was sitting on the railing and fell off. Can this be done from the information given? How?

Assignment for Monday, Jan 31

• Identify and be prepared to describe one or more areas of study or specific problems in biomechanics that you are most interested in, knowing more about, and/or perhaps do a literature review on

• Go to the Biomechanics world wide Home website and– Locate a website that deals with problems and issues in an area of special

interest to you– Give a short verbal summary of the contents of the site to the class.

Include in your comments the following: (1) site URL and description, (2)general purpose, (3) intended audience, and (4) specifically, how the site is beneficial to you and others.

– Read: (1) Hamill Ch 8 and 9 (Kinematics review); (2) Kreighbaum pp 537-555 & Adrian pp 131-134, 162-169