Yr 11 HPE BIOMECHANICS

Biomechanics is the study of How living things move Efficiency of movement Knowledge of biomechanical principles can help us to Understand how our bodies move Understand how we can make movement more efficient

Biomechanics is important in skill learning because it allows us to Develop new skills Detect & correct errors in performance Improve safety & Prevent injury Obtain a reference point from which to analyse our skills Develop new equipment designs

Skill phases Can be defined as “the breaking down of a movement into specific meaningful phrases” (Amezdroz et al, 2004). This means that a movement consists of a series of phases that are quite different in terms of techniques and the underlying principles of biomechanics (Amezdroz et al, 2004). Example: cartwheel has 5 different phases

Balance and stability If you do not fall over you are in equilibrium and therefore balanced. Balance is the ability to maintain the body in equilibrium while static (stationary) or dynamic (moving). When you are stable you are balanced and stability depends on Base of support (BOS) and Centre of gravity (COG)

Balance and stability Base of support (BOS) The area between the points in contact with the ground. Determines the level of balance Eg. One leg v 2 legs; close v wide stance, headstand v handstand Centre of gravity (COG) [or centre of weight ] The point at which the body’s weight is balanced. Can change position in relation to the body mass which means that it can be outside the body (pg 183)

Stability is the measure of the body’s reluctance to move out of equilibrium COG must be inside BOS Lose balance when COG falls outside the BOS To be stable COG is closer to the ground Increase the BOS Example Opponent being pushed will fall when COG goes outside BOS More stable when

Motion 3 types of motion GeneralAngular Linear (object traveling in a straight line)

Angular motion is when the body turns around its axis of rotation Longitudinal or vertical axis The line taken from head to toe vertically through the COG Eg. Ice skater spinning Horizontal or transverse axis The line taken from hip to hip through the COG Eg diver performing a triple somersault medial Also a horizontal axis taken from the navel to the small of the back Eg. Gymnast performing a cartwheel

Inertia can be defined as an objects responsiveness or its resistance to attempts to change its motion (Amezdroz et al, 2004). Inertia is the degree of difficulty in getting an object that is Stationary to move Moving to stop Inertia relates to mass Heavier = more difficult to move or stop Lighter = less difficult to move or stop

Rotational Inertia Motion that is rotational (ie. It turns about an axis) Radius of rotation the distance of mass from the axis. Rule: the further the mass from the axis of rotation, the greater its resistance to rotational movement Example: tuck v pike, spin with arms in v spin with arms out Mass

Momentum Levers - rigid rods or body segments that rotate around a fixed point or axis (eg. Bones) Force –something that causes a change in the body’s motion (eg. Muscle contraction) momentum - once a person or an object is moving Muscles of body contract to move bones which creates a force which can overcome inertia and so creates momentum. Involves speed – faster the object, the greater the momentum. Involves mass – heavier the object, the greater the momentum. Conservation of rotational momentum states that momentum will continue until a force is applied to change it.