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SYLLABUS CONTENT
How do the systems of the body influence and respond to movement?
Outline the interrelationship between biomechanical principles and the muscles, bones and joints of the body for safe movement
Including:
how biomechanical principles are applied to human movement, including motion, balance and stability, fluid mechanics and force
how biomechanical principles can be used to enhance safe movements
how biomechanical principles can be used to increase movement efficiency
WHAT IS BIOMECHANICS?
Bio = Human life/living things
Mechanics = The branch of mathematics that deals with forces, energy and motion
The study of biomechanical principles refers to a specialised area of sports science that seeks to apply the natural laws of physics and mechanics to provide an advantage to human performance and increase movement potential, while also enhancing safety. Biomechanics focuses on the development of sports equipment, training innovations and analysis tools to increase feedback and refinement of techniques, especially for more technically demanding sports and activities.
Biomechanics is often divided into two categories. The first is kinematics, which is the study of objects in motion. The second is kinetics, which is the study of the body that creates force.
MOTION
Motion refers to the specific path or movement of a body. In sport, this could be the movement of the human body (e.g. the speed an athlete runs during a running race) or an object that is manipulated by the human body and the force it applies to this object (e.g. a javelin being thrown). While some of these principles of motion are simply observed in sport, others can be targeted to maximise efficiency and lead to the development of improved technique or equipment.
TYPES OF MOTION
Linear Motion
Linear motion is movement in a straight line. When a sprinter runs from start to finish over 100 m, they run in a straight line to ensure they travel the least distance. Any slight deviations from this linear motion will result in increased distance, and therefore will increase the time.
Angular Motion
Angular Motion is motion in a circular movement around a central point. A gymnast performing a somersault demonstrates angular motion around their axis. Inefficient angular motion will result in less power, balance and poor technique.
General Motion
General Motion is a combination of linear and angular motion. The majority of sports utilise this. A swimmers arms represent angular motion, while their hips display linear motion as they glide through the water.
ACTIVITY - Newtons Laws of Motion
The biomechanical principle of motion is directly related to Newtons Laws. Copy in and complete the table. Use the link below to aid your research. Ensure you apply the three laws to practical sporting examples.
https://669659.medium.com/newtons-three-laws-of-motion-in-sports-924510aa7fde
FEATURES OF MOTION: Velocity, Speed, Acceleration and Momentum
Related to motion is the concept of distance and displacement, which are merely observable features of sport.
Velocity
Velocity refers to the speed of an object in a given direction and is calculated by using the the following formula:
Velocity = Displacement/Time
So, an athlete might have a velocity of 17 Km/h in a southeast direction. Velocity is different to speed, which does not have a direction attached to it.
Speed
Speed refers to how fast an object is moving regardless of the direction. It is calculated using the following formula:
Speed = Distance/Time
For example, an athlete might have a speed of 23 Km/h, which only indicates how fast they are moving, without any reference to the direction.
Speed and Velocity: Reflection
Watch the video and answer the following:
How does the concept of displacement differ from distance?
Outline the difference between speed and velocity.
Explain how speed and velocity may influence the effectiveness of a tennis serve.
Acceleration
Acceleration refers to the rate of change in velocity of a moving object. When acceleration is increasing, it is described as positive acceleration. For example, when moving from a stationary position to a jog and onto a fast sprint. When the opposite occurs and the body in motion is slowing down, it is called either deceleration or negative acceleration. It is calculated using the following formula:
Acceleration = (Final Velocity - Initial Velocity) / Time
Acceleration benefits athletes by allowing quick starts, faster directional changes, the ability to outpace opponents and increased power, offering a competitive advantage.
Momentum
Momentum refers to the quantity of motion an object has and is determined by both its mass and velocity. It is calculated using the following formula:
Momentum = Mass × Velocity
For example, a rugby player weighing 90 kg running at 10 m/s will have a greater momentum than a smaller player running at the same speed. Momentum is a key concept in collisions and impacts in sports, as objects or athletes with greater momentum are harder to stop. Momentum is a vector quantity, meaning it involves both speed and direction.
Balance and Stability
Balance and stability refer to the body’s ability to maintain control and remain in a state of equilibrium, whether stationary or in motion. In sport, balance is crucial for both static positions, like holding a gymnastics pose, and dynamic movements, such as running or changing direction quickly. Stability, which is influenced by factors like the athlete's center of gravity and base of support, helps ensure efficient movement and reduces the risk of injury by allowing better control of the body’s movements under various conditions. Improved balance and stability can enhance performance and technique in a wide range of activities.
Key Terms:
Balance
A person’s ability to control their equilibrium in relation to gravity only.
Stability
Your body's ability to return to a desired position or trajectory following a disturbance
General Motion
A state of no acceleration. It can be static (without movement) or dynamic (moving at a constant velocity).
FEATURES OF BALANCE AND STABILITY:
Centre of Gravity (COG), Line of Gravity (LOG) and Base of Support (BOS)
Centre of Gravity
The centre of gravity is the point in the body where weight is evenly distributed, allowing the body to stay balanced in all directions.
In the anatomical position, this point is typically located around the lower abdomen, just below the navel near the pelvis. The center of gravity can shift with different body positions and movements.
The COG changes with body position, impacting balance, stability, and force production in sports. For example, a runner’s COG is lower and in front of the pelvis due to their forward lean, which optimises acceleration. Lowering and shifting the COG helps athletes generate more force and promote stability, improving performance in activities like sprinting, gymnastics, and defensive stances.
Line of Gravity
The line of gravity is an imaginary vertical line from the center of gravity to the ground or surface the object or person is on.
The closer the line of gravity is to the center of the base of support the better balanced a person is in this position. If the line of gravity fall outside of the base of support the person must provide corrective muscle action, usually movement otherwise they will fall.
A sprinter's line of gravity must be in front of their base of support for forward movement; if it's within the base, they risk falling backward. A lower center of gravity shortens the line between the center and the ground, enhancing balance and stability.
Base of Support
The BOS refers to an imaginary line drawn around the parts of the body in contact with the ground at any given point. Below you can see these areas shaded in various body positions.
The larger the base of support the more stable the athlete is able to be. When an athlete is anticipating contact from an external player, they will naturally widen their base of support in the direction of force.
However, although increases in BOS can increase balance and stability it reduces your mobility. Therefore, a trade off occurs, as an increase in acceleration and agility reduces an individual's BOS and balance.
The Relationship Between COG, LOG and BOS
To maintain balance, the LOG must fall within the BOS. If the LOG moves outside the BOS, the body becomes unstable, leading to a loss of balance.
In sports, athletes manipulate their COG and BOS to optimize performance. For example, a sprinter leans forward at the start to shift the LOG close to the edge of their BOS, enabling quicker forward momentum. In contrast, a wrestler widens their stance, increasing the BOS to improve stability against force from opponents.
Activity - Practical Workshop
As a class we will participate in a variety of practical activities to highlight balance and stability. These may include:
Twister
Twister
Handstand Skills
Handstand Skills
Balance Holds
Balance Holds
Sumo Wrestling
Sumo Wrestling
COG Races
COG Races
Tug of War
Tug of War
Fluid Mechanics
Fluid mechanics refers to the movement of a body through liquid (water) or gas (air), and the forces that affect it. Any sport involving movement, whether of an object or the human body, is subject to the impact of the fluid it moves through. Generally, sports require this movement through the fluid to be as fast and efficient as possible.
Even with regards to water and air, there can be subtle differences in the fluid properties in different locations around the world. Swimming in salt water is different from swimming in fresh water, as the increased salt concentration increases the body’s ability to float. Air pressure decreases as altitude increases due to lowering levels of oxygen concentration. This will reduce the resistance of the air on an object flying through it. To enable the most efficient and effective movement possible, both technique development and equipment modification is used.
Flotation and Centre of Buoyancy
As a class we will read through page 196 of your textbook. Then answer the following:
Define the term fluid displacement
With reference to fluid displacement, explain why some things are buoyant and other sink.
Centre of buoyancy refers to: "The point at which the buoyant force acts on an immersed object (In simple terms, it's the spot in a floating or submerged object where the water "pushes up" the most)." How does understanding the center of buoyancy help a swimmer stay higher in the water and swim faster?
Fluid Resistance
Whenever an object moves through a liquid or gas (air), various resistance forces impact on the efficiency of this movement. This resistance is often referred to as drag, and any reduction of drag through technique refinement and equipment development will increase performance.
Drag is an oppositional force, which means it acts against the movement of an object through fluid.
Brainstorm
Brainstorm
Propose ways athletes can reduce drag to enhance performance. Consider not only equipment, but strategy and technique as well.
Profile Drag
Profile drag, is the resistance an object faces as it moves through a fluid, like air or water, due to its shape and surface area. This type of drag occurs because the object has to push fluid out of its way, creating a region of high pressure in front and a low-pressure wake behind it. The size of this wake increases drag, slowing the object down.
Four main factors affect profile drag:
Velocity: Faster movement through air increases resistance. Think of three sports where this is relevant.
Cross-Sectional Area: Larger areas face more resistance. What sports focus on reducing this?
Shape: Streamlined shapes reduce drag, like F1 cars or a cyclist's helmet.
Surface Texture: Smoother surfaces reduce drag. For example, the Speedo LZR swimsuit.
LZR Swimsuit
LZR Swimsuit
As a class watch the following video and read the article exploring the LZR swimsuit. Then complete the questions:
How does the design of the LZR swimsuit help swimmers reduce profile drag, and what impact does this have on their performance?
Why might some people believe that records set with the LZR swimsuit are not fully comparable to those set without it? What does this tell us about the importance of drag reduction in competitive swimming?
https://www.swimmingworldmagazine.com/news/can-world-records-supersede-the-super-suit-era/
BUILD YOUR KNOWLEDGE
Read page 198 of the Cambridge textbook and discuss.
The Magnus Effect
Read through the following handout. We will then participate in a variety of practical activities to highlight the magnus effect and its impact on performance. These may include:
Soccer
Soccer
Golf
Golf
Table Tennis
Table Tennis
Force
Force refers to the push or pull upon an object that arises when it interacts with another object, often resulting in a change in motion. Forces that arise from direct and applied contact are called contact forces, such as striking a ball in cricket, and there are also non-contact forces such as gravity.
How The Body Applies Force
How The Body Applies Force
The body produces force through the coordinated contraction of skeletal muscle, resulting in movement of the skeleton. Sport requires the application of these forces against other objects and surfaces in the competitive environment.
Key factors in force production includes:
Muscle Contraction: When muscles contract, they pull on tendons attached to bones. This pulling action generates force that can move parts of the body.
Lever Systems in the Body: Bones act as levers, and joints serve as pivot points. This converts a smaller input force (from your muscles) into a larger output force.
Ground Reaction Force: When we push against a surface, like the ground, it pushes back with an equal and opposite force (Newtons 3rd law). This force enables movements like jumping and running.
Activity - Applying Force
Watch the following video exploring the concept of force. Then CUBE and answer the question below:
Explain how an athlete applies force to perform a squat jump.
How The Body Absorbs Force
Often in sport, the body encounters an external force that must be absorbed and controlled. This is done primarily through the following methods:
Joints as Shock Absorbers - Joints like the knees, hips, and ankles absorb impact by bending and flexing, distributing force to protect bones and muscles.
Controlled Muscle Contraction - Muscles absorb force through eccentric contractions (lengthening under tension), especially during movements like landing, which helps control impact.
Tendons and Ligaments - Tendons and ligaments stretch slightly under force, using their elasticity to absorb and distribute impact, protecting joints and muscles.
Body Position and Technique - Proper positioning, like bending knees when landing, spreads force across the body, reducing stress on any one area and preventing injury.
Using Biomechanical Principles For Safe Movement
As a class read through page 202 of the textbook. Then CUBE and answer the question below:
Using an example, explain how biomechanical principles can be used to enhance safe movements.
Using Biomechanical Principles For Movement Efficiency
As a class read through page 203-205 of the textbook. Then complete the answer the following:
Define movement efficiency and provide an example of it being applied to a sport.
Watch the following video, then, explain (with examples), how biomechanics may increase the movement efficiency and technique of martial artists.
WRITING TASK - RESPONSE WRITING
WRITING TASK - RESPONSE WRITING
Go to page 206 of the Cambridge textbook. Choose one revision question and complete the following:
CUBE the question. Then, use your verb sheet and ALARM matrix to formulate a response:
WRITING TASK - GLUE
WRITING TASK - GLUE
Assess your response by applying the GLUE method. Highlight the following:
Green - Specific verb requirements/language
Pink - Links to the question
Orange - Syllabus-specific content
Yellow - Examples
Award yourself a mark out of 5.
Annotate what you did well and areas for improvement.
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