How Do I Move?Chapter 7

The Science of Biomechanics

Biomechanics

• The study of the structure and functions of biological systems by means of the methods of mechanics

Hatze, 1974We might think of biomechanics as the “physics

of human movement”

Biomechanics Examines the internal and

external forces acting on the human body and the effects produced by these forces

Aids in technique analysis and the development of innovative equipment designs

Draws on knowledge from sports medicine, physical therapy, kinesiology, and biomechanical engineering

They all fall under the following 4 categories• Stability• Maximum Effort• Linear Motion• Angular Motion

The 7 Basic Principals of Biomechanics

• The lower the centre of mass, the larger the base of support, the closer the centre of mass to the base of support, and the greater the mass, the more stability increases.

Principle 1 – Stability

• The production of maximum force requires the use of all possible joint movements that contribute to the task’s objective.

Principle 2 – Maximum Force

• The production of maximum velocity requires the use of joints in order – from largest to smallest.

Principle 3 – Maximum Force

• The greater the applied impulse the greater the increase in velocity.

Principle 4 – Linear Motion

• Movement usually occurs in the direction opposite that of the applied force.

Principle 5 – Linear Motion

• angular motion is produced by the application of a force acting at some distance from an axis, that is, by torque. The application of torque produces changes in angular motion.

Principle 6 – Angular Motion

• angular momentum is consistent when an athlete or object is free in the air. Once an athlete is airborne, he or she will travel with a constant angular motion.

Principle 7 – Angular Motion

• Planes– Sagital– Frontal, Coronal– Transverse

• Axis– Horizontal– Antereoposterior– Longitudinal

Review of Movements from Anatomy

Motion

• Kinematics– describing movements with respect to time and

space

• Kinetics– examines the forces that produce the movement

and result from the movement

Qualitative Analyses

It requires:

A framework within which skilled performance can be observed

A set of principles with which movement can be analyzed

A checklist to use when identifying errors

Techniques to use for error detection and correction

Involves obtaining information, visually or auditorily, Involves obtaining information, visually or auditorily, to asses performanceto asses performance

Quantitative Biomechanics

Types of Motion

Linear motion Angular motionAngular motionGeneral motionGeneral motion

Translation refers to movement of the body as a unit without individual segment parts of the body moving relative to one another

Linear Motion When all parts of the body move the same distance, in the same direction, at the same time

Rectilinear motion occurs when movement follows a straight line

Curvilinear motion occurs when the movement path is curved but also linear

Types of Motion

Identify the external forces acting on the human body

Describe the resulting motion

Describe the expected path and motion of any projectile

Differentiate between similar skills

Determine the degree of stability possessed by an athlete

Understand the causes and effects of actions

Qualitatively analyze simple sport skills that involve throwing, striking, or hitting an object

Objectives:

Step 1 Identify the system to be studied, which is to separate the

object of interest from its surroundings

Step 2 Identify the frame of reference in which the movement

takes place

Step 3 Identify the type of motion that is occurring, the body

planes in which movement takes place (sagittal, frontal, or transverse), and

Identify the axes of rotation about which rotational motion occurs (sagittal, frontal, or vertical)

Preliminary Steps for Analyzing Human Motion