1. 11PDHPE Preliminary Course
Core 2: Focus Question 3
How do biomechanical principles influence movement?

2. The biomechanics of movement
Biomechanics is the science concerned with forces and the effect of these forces on and within the human body.
A knowledge of biomechanics helps us to:
Choose the best technique to achieve our best performance with consideration to our body shape.
For instance, an understanding of the biomechanical principles that affect athletic movements, such as the high jump, discus throw, golf swing and netball shot, improve the efficiency with which these movements are made. This improves how well we perform the skill.
Reduce the risk of injury by improving the way we move
Design and use equipment that contributes to improved performance.

3. Motion
Motion is the movement of the body from one position to another.
Some bodies are inanimate (non-living) such as basketballs, shot puts
Whilst other bodies are animate (living) such as golfers, footballers.
Motion itself can be divided into 3 categories:
Linear
Angular
General

4. Linear Motion
Linear motion takes place when a body and all parts connected to it travel the same distance in the same direction and at the same speed.
The easiest way to determine if a body is experiencing linear motion is to draw a line connecting two parts of the body
For example, the neck and hips. If the line remains in the same position when the body moves from one position to another, the motion is linear.

5. Angular Motion
Angular motion is the motion of a body about a fixed point or fixed axis.
Angular movement plays the dominant role because most of an athlete’s movements result from the swinging, turning action of the athlete’s limbs as they rotate around the joints.
Many terms are used to refer to angular motion.
Movements include:
Rotating
Spinning
Swinging
Circling
Turning
Rolling
Pirouetting
Somersaulting
Twisting
All of these terms indicate that an object or an athlete is turning through an angle, or number of degrees. In sports such as gymnastics, skateboarding, basketball, diving, figure skating, and ballett, the movements used by athletes include quarter turns (90 degrees); half turns (180 degrees); and full turns, or “revs” (revolutions), which are multiples of 360 degrees

6. General Motion
General motion is a mix of linear and angular, which we simply call general motion. In sport, a mix of linear and angular movement is most common.
Even those sport skills that require an athlete to hold a set position involve various amounts of linear and angular motion.
For example, a gymnast balancing on a beam. In maintaining balance on the beam, the gymnast still moves slightly. This movement may contain some linear motion but will be made up primarily of angular motion occurring around the axes of the gymnast’s joints and where the gymnast’s feet contact the beam.
Most visible combination of angular and linear motion occurs in a wheelchair race. The swinging, repetitive angular motion of the athlete’s arms rotates the wheels. The motion of the wheels carries both the athlete and the chair along the track. Down the straightaway, the athlete and chair can be moving in a linear fashion. At the same time the wheels and the athlete’s arms exhibit angular motion

7. motion
Improving performance in activities that encompass linear motion usually focuses on modifying or eliminating technique faults that contribute to any non-linear movements.
Excessive up and down, rotational and lateral movements are examples of faults that erode performance directed towards achieving the shortest, most efficient pathway.
Swimmers who use an irregular arm pull that results in a zigzag movement pattern along the pool surface are examples of poor application of linear motion.
For swimmers, excessive movement increases drag which slows down a swimmer.
But what is drag and how does a swimmer eliminate it to enhance their swimming? ;

8. Velocity Velocity is equal to displacement divided by time.
Displacement is the movement of a body from one location to another in a particular direction, or an ‘as the crow flies’ measurement.
Velocity is used for calculations where the object or person does not move in a straight line.
An example is a runner in a cross-country race.
Activities to improve speed may also relate to velocity.
Improving the velocity of implements such as javelins or arrows requires specialised training, as does improving the performance of athletes in non-linear events such as marathons.

9. SPEED
Speed is equal to the distance covered divided by the time taken to cover distance
So, if a runner runs 100m in 12 secs:
Speed is important in most sports and team games. The player who can move quickly has a distinct advantage in games such as touch football, rugby and soccer because not only is that player difficult to catch, but he/she can use their speed to gather opponents quickly in defence.
Much of our potential for speed is genetic and relates to the type of muscle fibre in our bodies. However, individuals can develop their speed as a result of training and technique improvements, the basis of which is the development of power and efficiency of movement.

10. acceleration A change in velocity is known as acceleration.
A change can be a change in linear motion - the “speed” of the object increase
Or it can simply be a change in direction.
Acceleration is caused by applying a force to an object - stationary or moving.
Acceleration can be positive or negative (often called deceleration) depending on whether the change in velocity is positive or negative.
Acceleration can also be uniform or varied.
Uniform acceleration - constant change in velocity, such as gravity acting upon a discus flying through the air.
Varied - This could be from an opponent tackling a forward in rugby, with changes in velocity including positive and/or negative acceleration, and multiple changes in direction.
Acceleration is a vital component of performance and relates directly to the athlete’s ability to produce power.
Acceleration in sport is used by athlete’s as they change their velocity to beat opposing players
Faster acceleration is beneficial - opposition has less time to react, and helps you reach your top speed faster.
Acceleration relates directly to agility - ability to change direction at speed requires fast changes in velocity, and therefore, faster acceleration allows for better agility.

11. Momentum Momentum the quantity of motion the body possesses
Mass refers to the amount of matter in a body
The application of the principle of momentum is most significant in impact or collision situations. The principle can be applied to certain sporting games such as rugby league and rugby union, where collisions in the form of tackles are part of the game. However, collisions between players in sporting events tend to exhibit different characteristics to that of objects due to a range of factors, including:
The mass differences of the players — in most sports, we do not see the huge variations in mass that we find between cars, bicycles and similar objects
Elasticity — the soft tissue of the body, which includes muscle, tendons and ligaments, absorbs much of the impact. It acts as a cushion.
Evasive skills of players which often result in the collision not being ‘head-on’. In some cases there may be some entanglement just prior to collision, such as a palm-off or fend. This lessens the force of impact.
The momentum described in the previous situation is called linear momentum because the object or person is moving in a straight line.

12. Momentum
There are numerous instances in sport where bodies generate momentum but they do not travel in a straight line;
For example, a diver performing a somersault with a full twist, football kick, discus throw and golf swing.
In each of these cases, the body, part of it, or an attachment to it such as a golf club or tennis racquet, is rotating.
We call this angular momentum.
Angular momentum is the quantity of angular motion in a body or part of a body
Angular momentum is affected by:
Angular velocity - For example, the distance we can hit a golf ball is determined by the speed at which we can move the club head.
The mass of the object - The greater the mass of the object, the more effort we need to make to increase the angular velocity. It is relatively easy to swing a small object such as a whistle on the end of a cord. Imagine the effort that would be needed to swing a shot-put on a cord.
The location of the mass in respect to the axis of rotation. With most sport equipment, the centre of mass is located at a point where the player is able to have control and impart considerable speed.
Take baseball bats and golf clubs for example. Here, the centre of mass is well down the shaft on both pieces of equipment. This location enables the player to deliver force by combining the mass of the implement at speed in a controlled manner, thereby maximising distance.