Biomechanics And Sports | Chapter 8 | Class 12 | Notes 2026

Last updated on February 6th, 2026 at 01:19 pm

Biomechanics in Sports

Meaning

Biomechanics is the science concerned with the analysis of the mechanics of human movement. It explains how and why the human body moves.

It is the study of the function and motion of the mechanical aspects of biological systems.

Biomechanics tells us how our muscles, bones, tendons, and ligaments work together to produce movement.

It gives us a detailed analysis of any sports movements, which helps to minimize the risk of injury and improve sports performance. 

Importance Of Biomechanics In Sports

Improves sports performance: Biomechanics tells us the right techniques for effective and efficient results by using minimum muscular force and getting maximum results.   

Improvement in technique: Biomechanics helps to improve new techniques, which helps us to get more results 

Helps to develop the best sports equipment: Biomechanics helps us to make correct and scientifically proven equipment.

Improvement in training: Coaches can give the best training to athletes on the basis of scientific knowledge. He can analyze the player’s movement in a better way.

Prevents injuries: It helps us to know the forces that can lead to the injuries during the game situation. 

Knowledge of safety principles: Biomechanics gives the understanding to analyze different safety movements 

Helps in research work: It helps to impart scientific teaching and learning processes. 

Creates confidence in players: Players come to know the correct techniques to execute the movement. Thus it improves the confidence of the player. 

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Newton’s Law of Motion & Its Application in Sports

Man is said to be the man of action. So, movements are involved everywhere. For every moment there is motion. Therefore everything that moves is governed by the ‘Laws of motion’.

These laws of motion were formulated by Sir Isaac Newton in 1687. He explained and investigated that every motion is under the impact of following laws of motion

First Law of Motion

A body remains at rest or in uniform motion unless acted upon by an external force. 

Scientific Basis: Inertia is the tendency of an object to resist changes in its state of motion.

Application in Sports

• A football remains stationary until kicked.
• In archery, the arrow stays at rost until released.
• A sprinter remains still on the blocks until the starting gun fires.

Second Law of Motion

The Second Law of motion is also named the ‘Law of Acceleration’.

According to this law, the rate of change in the velocity of an object is directly proportional to the force applied and inversely proportional to the mass of the body. 

Force Mass Acceleration (F=mxa)

Scientific Basis: The acceleration of an object depends on its mass and the force applied.

Application in Sports

• A heavier shot put requires more force to accelerate.
• In badminton, a light racket and strong swings produce high shuttle speed.
• In boxing, a punch’s impact depends on the boxer’s mass and acceleration.

Third Law of Motion

This law is also known as the ‘Law of Action and Reaction’

For every action, there is an equal and opposite reaction.

Forces always occur in pairs-when one body exerts a force, the other reacts.

Application in Sports

• A swimmer pushes water backward to move forward.
• A basketball player jumps by pushing against the ground.
• A long jumper pushes off the take-off board to propel forward.

Lever, Types of Levers and Their Applications in Sports

Lever

Levers are rigid structures (bones) that rotate around a fulcrum (joint) to move a load using effort (muscle force).

Components of a Lever

• Fulcrum: The pivot point around which the lever rotates.
• Effort: The force you apply to the lever.
• Load (or Resistance): The object or force you’re trying to move or overcome.

Types of Levers

First-class lever:

Structure: Fulcrum between force and load. Example: Nodding the head (neck joint as

fulcrum)

Sports Application: Balancing in gymnastics, yoga poses like Sirsasana

Second-class lever:

Load positioned between the effort and the fulcrum.

Structure: Load between fulcrum and effort

Example: Standing on tiptoes (ball of foot as fulcrum)

Sports Application: Jumping in basketball, lifting weights with calf muscles

Third-class lever:

Effort is positioned between the fulcrum and the load.

Structure: Effort between fulcrum and load

Example: Bicep curl (elbow as fulcrum)

Sports Application: Batting in cricket, throwing a javelin, tennis forehand

Scientific Insight:

• They allow speed and range of motion but it requires more effort.
• Third-class levers are most common in the human body.

Equilibrium-Dynamic & Static and Centre of Gravity and Its Application in Sports

Equilibrium refers to a state in which all the forces acting on a body are balanced, resulting in no change in motion. It is essential for maintaining stability, control, and postural alignment in sports.

There are two types:

Types of Equilibrium

1. Dynamic Equilibrium
2. Static Equilibrium

Dynamic Equilibrium: Dynamic equilibrium is the balance of the body during movement 

Static Equilibrium: It is the balance of the body during rest or in a stationary position.

a. Static Equilibrium

A body is in static equilibrium when it is at rest and all external forces and torques acting on it are balanced.

Examples in Sports:

• A gymnast holding a handstand or headstand
• An archer maintaining posture before releasing the arrow
• A football goalkeeper standing still before a penalty kick

Key Factors Enhancing Static Equilibrium:

• Vertical alignment of COG over base (e.g.. yoga poses like Tadasana)
• Wide base of support (e.g., feet apart in wrestling stance)
• Low centre of gravity (e.g., crouched position in judo)

b. Dynamic Equilibrium

A body is in dynamic equilibrium when it is moving at constant velocity and the forces acting on it are balanced.

Examples in Sports:

• A sprinter maintaining stride during mid-race
• A swimmer gliding through water after a dive
• A cyclist cruising at constant speed

Key Factors Enhancing Dynamic Equilibrium

• Core strength for balance during motion
• Neuromuscular coordination to adjust posture dynamically
• Proper technique to minimize unnecessary force deviations

Center Of Gravity

Centre of Gravity is the point in a body where its entire weight is considered to act. It is the balance point of the body’s mass.

Scientific Insight:

• In uniform objects, COG is at the geometric center.
• In humans, COG shifts based on posture, limb position, and movement.
• Lowering COG increases stability; raising it increases mobility.

Application in Sports

Stability-Oriented Sports

Wrestling: Athletes lower their COG by bending knees and widening stance to resist being thrown.

Gymnastics: Balancing on beams or rings requires precise control of COG over the base of support.

Yoga: Poses like Vrikshasana or Garudasana demand vertical alignment of COG for balance.

Movement-Oriented Sports

High Jump: Athletes arch their body to allow COG to pass below the bar while the body clears it.

Long Jump: COG is projected forward and upward for maximum distance.

Skating: Shifting COG side-to-side allows smooth turns and balance during motion.

Equipment-Based Sports

Golf: Swing mechanics depend on maintaining COG within the stance to generate power and accuracy.

Shooting: Stable COG helps maintain aim and reduce sway.

Factors Affecting COG in Athletes

Body Composition: Taller athletes have higher COG; shorter athletes have lower COG.

Posture and Limb Position: Raising arms or leaning shifts COG.

Gender Differences: Females generally have lower COG due to wider pelvis and shorter torso.

Training to Control COG and Equilibrium

Balance drills: BOSU (Both Sides Utilized) ball exercises, single-leg stands

Core strengthening: Planks, bridges, Pilates

Dynamic movement training: Agility ladders, plyometrics

Friction & Sports

Friction and Its Effects in Sports

• Friction is a resistive force that occurs when two surfaces come into contact and attempt to move relative to each other.
• It plays a crucial role in movement control, grip, propulsion, and performance efficiency in sports.

Types of Friction

a) Static Friction

Prevents movement between two surfaces at rest. Example: A sprinter’s shoes grip the track before the race begins: a gymnast balances on a beam. 

b) Dynamic (Kinetic) Friction

Acts when motion has already started. Example: A football sliding across wet turf; a baseball player sliding into a base.

c) Rolling Friction

Resistance when an object rolls over a surface.

Example: A basketball rolling across the court; a bowling ball gliding down the lane.

d) Liquid Friction (Hydrodynamic Drag)

• Resistance experienced by a body moving through a liquid medium.
• Example: A swimmer experiences drag while moving through water; a rower’s oar faces resistance during each stroke.
• Reduced by: Streamlined body position, tight swimsuits, hydrodynamic equipment.

e) Air Friction (Aerodynamic Drag)

• Resistance experienced by a body moving through air.
• Example: A cyclist leans forward to reduce air resistance; a sprinter’s clothing and posture affect drag.
• Reduced by: Aerodynamic suits, helmets, streamlined equipment, low-drag body positions.

Positive Effects of Friction in Sports

• Enhances grip and traction (e.g., spikes in athletics)
• Improves stability and balance (e.g., wrestling stance)
• Allows controlled movement (e.g., skiing turns)
• Supports safe landings and take-offs (e.g., gymnastics)
• Enables propulsion in water and air (e.g., swimming strokes, ski jumping)

Negative Effects of Friction in Sports

• Causes energy loss and slows movement (e.g., rough turf in football)
• Leads to equipment wear and tear (e.g., tennis racket strings, shoe soles)
• Generates heat, causing abrasions or burns (e.g., mat burns in wrestling)
• Increases drag in water and air, reducing speed (e.g., swimming. cycling)

Managing Friction in Sports

To increase friction:

• Use rubber soles, chalk, resin, textured gloves, cleats
• Wear grip-enhancing gear (e.g.. gloves in gymnastics, boots in football)

To reduce friction:

• Apply lubricants (e.g., wax on skis, oil on bowling lanes)
• Use smooth surfaces (e.g., synthetic tracks, polished courts)
• Wear aerodynamic suits and streamline body posture (e.g., cycling, swimming)

Sport-Specific Examples

• In athletics, friction between shoes and track determines sprint efficiency.
• In gymnastics, hand friction ensures safe execution of routines.
• In football, boot grip affects agility and control.
• In skiing, waxed skis balance glide and control.
• In wrestling, mat friction supports balance and technique.
• In swimming, liquid friction is minimized through streamlined posture and suits.
• In cycling, aerodynamic drag is reduced by posture and gea design.
• In bowling, lane oiling controls ball speed and spin.

Projectile In Sports

A projectile is any object thrown or propelled into space upon which only gravity and air resistance act.

In sports, projectiles include implements like javelins, discus, shot puts, balls, and even the human body during jumps and dives.

Trajectory is the curved path that a projectile follows through the air under the influence of gravity and air resistance. In sports, it’s the flight path of a ball, javelin, or even an athlete during a jump.

Factors affecting the projectile trajectory

a) Angle of Release

The angle at which the object is thrown or hit. It affects how and how far the object travels.

Theoretically, 45° gives maximum horizontal distance. In sports, the best angle depends on the goal-height or distance.

Examples:

• Long Jump: Low angle (around 20°) helps maintain speed and distance.
• High Jump: Higher angle (45° or more) helps gain vertical height.
• Tennis Serve: Low angle (3-15°) helps direct the ball downward into the service box.
• Basketball Shot: Often above 45° to arc over defenders and reach the hoop.

b) Speed of Release

How fast the object is moving when it is released. More speed means more distance and height. Speed is often more important than angle for range.

Examples:

Javelin Throw: Faster release = longer throw.

Shot Put: Strong push = greater distance.

Football Kick: Powerful kick = ball travels farther.

Volleyball Spike: High-speed arm swing increases ball velocity and impact.

c) Height of Release

It denotes how high above the ground the object is released. Higher release gives more time in the air, increasing horizontal distance. This factor explains why taller athletes often have an advantage in throwing events

Examples:

Shot Put: Thrown from shoulder height; optimum angle is less than 45°.

Basketball Jump Shot: Released from above head level for better arc.

Golf: Hitting uphill requires a higher angle due to elevated landing surface.

Tennis Serve: Racquet is high during contact, helping the ball reach the service box.

d) Air Resistance

Air pushes against the object, slowing it down.

It affects the flight path, especially for light or fast-moving objects.

Factors that increase air resistance:

• Larger surface area
• Faster speed
• Rough surface texture
• Lower mass

Examples:

Badminton Shuttle: Slows down quickly due to feathers and low mass.

Cricket Ball Swing: Seam and shine affect air flow and movement.

Frisbee: Flat shape and spin make it sensitive to air resistance.

Skydiving: Parachute increases drag to slow descent.

e. Spin and Aerodynamics

Spin changes how air flows around the object, affecting lift, dip, and curve.

Types of Spin:

Top Spin: Ball dips faster (e.g., tennis forehand).

Back Spin: Ball floats longer (e.g., golf chip shot).

Side Spin: Ball curves sideways (e.g., banana kick in football).

Aerodynamics: Shape and surface design help reduce air resistance and improve flight.

Examples:

Table Tennis: Spin controls bounce and direction.

Football: Curved free kicks use side spin.

Golf: Back spin helps control ball flight and landing.

Tennis: Top spin helps dip the ball into court.

f) Gravity

A constant force pulling everything down object goes and how fast it comes down toward Earth (9.8 m/s). It affects how high the

Key Points:

• At the highest point (apex), vertical speed = 0.
• Gravity does not affect horizontal speed directly.
• It causes the object to follow a curved path (trajectory).

Examples:

Basketball Shot: Ball arcs and falls into the hoop.

High Jump: Athlete goes up, then gravity pulls them down.

Long Jump: Gravity brings the jumper back to the ground.

Juggling: Balls rise and fall due to gravity.

Training Implications

Athletes train to optimize release angle, speed, and body posture. Understanding projectile mechanics helps in technique correction, injury prevention and performance enhancement

Types Of Movements

Flexion

It describes a bending movement that decreases the angle between two body parts, that is bones of the limb at a joint. Flexion refers to movement in the anterior direction.

It happens when muscles contract and move your bones and joints 

Example: Elbow flexion is decreasing the angle between the radius and the humerus. Knee flexion is decreasing the angle between the femur and tibia.

Flexion of the shoulder or hips refers to the movement of the arm or leg forward.

Extension

It is the opposite of flexion, it is a movement that increases the angle between two body parts.

Extension refers to movement in the posterior direction.

Extension at the elbow is to increase the angle between the ulna and the humerus. Extension of the knee is to increase the angle between the tibia and the femur.

Abduction 

Abduction is a movement that pulls a structure or part away from the midline of the body. The muscles which create this type of motion are known as an abductor.

Abduction of the wrist is also known as radial deviation.

Swinging the arms laterally from the side of the body up to the shoulder or moving the legs away from the midline is abduction are some examples. 

Adduction

It refers to the movement that pulls apart towards the midline. When the arms straight out at the shoulders bring down to their sides is adduction.  

Arms closing towards the chest, bringing the knees together, bringing all the fingers or toes together, and the thumb back to the normal position are some of examples of adduction.

Biomechanics in sports chapter 8 CBSE, class 12 Physical Education notes. This CBSE Physical Education class 12 note has a brief explanation of every topic that the NCERT  syllabus has.

You will also get ncert solutions, CBSE class 12 Physical Education sample paper, and CBSE Physical Education class 12 previous year paper.

Frequently Asked Questions

Multiple Choice Questions

1. The Law of inertia is

a. First Law of motion

b. Second Law of Motion

c. Third law of motion

2. A volleyball player hitting the ball hard for a smash, is an example of

a. First Law of Motion

b. The second law of motion

c. Third law of motion

3. Which is not a type of movement

a. Flexion

b. Adduction

c. Contraindication

d. Abduction

4. Moving an art away from the midline is

a. Flexion

b. Extension

c. Abduction

d. Adduction

5. The Second Law of motion is

a. Law of inertia

b. Law of acceleration

c. Law of gravity

d. Law of action-reaction

Final Words

From the above article, you must have learned about ncert CBSE class 12 Physical Education notes of chapter 8 Biomechanics in sports. We hope that these crisp and latest Physical Education class 12 notes will definitely help you in your exam.