Exercise Science Section 15: Biomechanical Principal and Applications An Introduction to Health and Physical Education Ted Temertzoglou Paul Challen ISBN

Equilibrium and the Conservation of Energy Newton’s theory (and biomechanics) rests on two assumptions: –Equilibrium –More than one force acts on a body, but no change in velocity results –Conservation of energy –Energy can never be created or destroyed, but can only be converted from one form to another

Isaac Newton’s “Model Universe” Three Laws of Motion –The Law of Inertia Every object in a state of uniform motion tends to remain in that state of motion unless an external force is applied to it –The Law of Acceleration A force applied to a body causes an acceleration of that body of a magnitude proportional to the force, in the direction of the force, and inversely proportional to the body’s mass –The Law of Reaction For every action there is an equal and opposite reaction

Types of Motion Linear (or translational) motion –Movement in a particular direction –Force generated by the athlete’s muscles and the resulting motion is in a straight line Rotational motion –Movement about an axis –Force does not act through the centre of mass, but rather is “off-centre,” and this results in rotation

Lever Systems Every moveable bone in the human body is part of a lever system that facilitates movement Three classes of levers –Class I lever (e.g. teeter-totter) –Class II lever (e.g. wheelbarrow) –Class III lever (e.g. snow shovelling)

Lever Systems Class I lever (e.g. teeter- totter) –The fulcrum (axis) is located between the force (effort) and the resistance load

Lever Systems Class II lever (e.g. wheelbarrow) –The resistance is between the force and the fulcrum

Lever Systems Class III lever (e.g. shovelling) –The force is between the fulcrum and the resistance

Seven Principles of Biomechanics The seven principles of biomechanics –Allows you to gain insight into movement dynamics The Coaching Association of Canada’s National Coaching Certification Program (NCCP) Level 2 Theory course sets forward these seven principles grouped into four broad categories: –Stability –Maximum effort –Linear motion –Angular motion

Stability Principle 1: –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 has four subcomponents: –The height of the centre of mass –The line of gravity –The base of support –Mass

Maximum Effort Principle 2: –The production of maximum force requires the use of all possible joint movements that contribute to the task’s objective

Maximum Velocity Principle 3: –The production of maximum velocity requires the use of joints in order – from largest to smallest

Linear Motion Principle 4: –The greater the applied impulse, the greater the increase in velocity

Principle 5: –Movement usually occurs in the direction opposite that of the applied force Linear Motion

Angular Motion Principle 6: –Angular motion is produced by the application of a force acting at some distance from an axis (torque)

Angular Motion Principle 7: –Angular momentum is constant when an athlete or object is free in the air

Applications in Biomechanics Performance improvement –Coaches and athletes focused on “performance improvement” within the aspects of technique and sport training Injury prevention and rehabilitation –High level of interest in biomechanics from sports medicine specialists, trainers, and injured athletes in relation to “injury prevention and rehabilitation” Fitness and personal training –Biomechanical analysis can be applied both to exercise and to equipment

Injury Prevention and Rehabilitation Progressive resistance training to improve muscular endurance, size, and tensile strength of both muscle and connective tissue can be integrated into the off- and pre-season schedule Specific design of aerobic and muscular warm- up tailored to the activities planned for the workout will bring more injury prevention value to the session All key muscles to be used must be stretched Muscle imbalance needs to be addressed

Fitness and Personal Training Biomechanical analysis begins by examining the method of execution of an exercise; such analyses enable one to give advice concerning: –The position of joints to isolate specific muscles –How to align the movement to the muscle –How to combine muscles for optimal results –The optimal speed for the objective –The best starting position and range of motion for an exercise –How to modify the leverage to gain a greater strength output