biomechanics of cricket

BY-

Dr. SURYAMANI BPT, MSPT(HONS.)

BIOMECHANICS OF CRICKET

MECHNICAL ANALYSIS OF SPORTS SKILL

IN-SWING/OUTSWING BOWLING IN

CRICKET

NECESSITY OF UNDERSTANDING BIOMECHANICAL PRINCIPLES IN CRICKET

Difficulty of the skill dramatically increases when the young players move from batting slow-moving or stationary(batting tee)objects,to balls thrown with greater speed and spin.

Principles like strength, balance, inertia and coordination, force-time and force –motion.

CONTENTS:--

Brief description of skill Objective of the skill Mechanical principle of the skill Objective of the principles Analysis of the skill Application of the principles

Brief description of the skill

Swing bowlers are pace bowlers who,apart from being fast. Also use the seam of the ball to make it travel in a curved path through the air. Make the swing of the ball towards the batsman or away from batsman.

Objective of the skill

The main objective of the bowler is to take wickets by tight line and length.

Mechanical principle of the skill

Momentum Arm force Inertia Gravity Magnus effect

Analysis of the skill

The grip Back foot contact Point of release Use of the swing

The grip- In swing An in swinger is bowled by holding the ball

with the seam vertical and the first two fingers slightly across the seam so that it is angled a little to the leg side.

Once the ball has worn and been polished so that one side is rougher than the other, the rough side is placed on the leg side. The ball is placed on the pad of the thumb. This thumb position locks the wrist in a position inclined to the leg side.as shown in fig.

The Grip- Out swing A Right-armed bowler bowling outswing

will move the ball away from a right-handed batsman. The 1st and 2nd fingers are placed on the top of the ball and spread either side of the seam.

The side of the thumb is placed on the underneath of the ball directly on the seam. To make the ball swing, ensure that the seam remains vertical and angled away from the batsman.

Back foot contact – in swinger

In swing can be bowled from side-on, mid-way or chest on positions. But bowlers usually tend to pitch it in the good length spot or up to the batsman. It is the wrist position that is crucial, not the position of hips or shoulders.

Back foot contact – out swinger

The bowler attempts to get as side on as possible. A high arm action is also required. The shiny side of the ball must be pointing away from the body, so that the rough side is on the bowlers side. The seam is usually held at a slight angle with the seam pointing to around second slip.

Point of release- inswing When the bowler delivers the ball, he angles the

seam so that it points slightly to the leg side. To help achieve this position the bowling arm should be near vertical, brushing close to the ear.

At release the wrist should remain cocked so as to help impart backspin along the orientation of the seam. The angle of the seam to the direction of motion produces an aerofoil effect as the ball moves through the air, pushing it to the leg side.

This is enhanced by differential air pressure caused by movement of air over the rough and smooth surfaces, which also tends to push the ball to the leg side. The result is that the ball curves, or swings in to the batsman.

Point of release- outswing

To bowl outswing, the bowler attempts to get as side on as possible. A high arm action is also required. The shiny side of the ball must be pointing away from the body, so that the rough side is on the bowlers side.

The seam is usually held at a slight angle with the seam pointing to around second slip. The arm in which the ball is held usually comes down across the bowlers body to the off side after delivery.

Application of the principles

Momentum P=m*v

“Product of mass and velocity”. In bowling long run and forward flex

gives momentum to the bowler.

Arm force

From back foot to ball release

A bowler get Force mainly from shoulder and wrist.

InertiaFrom run up to back foot contact.

By Newton's law“A body at rest/motion remains in

rest/motion unless& until external force is applied to over on it”.

Gravity

The force external by earthThe centripetal (pulling force)

Magnus effect on ball

Magnus effect

The Magnus effect is the phenomenon whereby a spinning object flying in a fluid creates a whrilpool of fluid around itself, and experiences a force perpendicular to the line of motion.

BATTING

STANCE The stance is the position in which a

batsman stands in order to have the ball bowled to him. An ideal stance is "comfortable relaxed and balanced," with the feet 40 cm apart, parallel and astride the crease.

The front shoulder should be pointing down the wicket, the head facing the bowler, the weight equally balanced and the bat near the back toe.

As the ball is about to be released, the batsman will lift his bat up behind up in anticipation of playing a stroke, and will shift his weight onto the balls of his feet.

By doing this he is ready to move swiftly into position to address the ball once he sees its path out of the bowler's hand.

BATTING

Front foot Back foot

FIELDING

Catching.

Ground fielding.

Wicket keeping.

FRONT FOOT TAPING- legs in same line, hip, shoulder

pointing towards bowler, taping bat on point of the right toe.

(Friction ,leverage system, stable equilibrium, zero acceleration.)

BACK LIFT- bat pointing towards ‘point region’, Bat should be raised on hip level, top hand fore arm parallel to the ground, both hands not to touch the body.

(Friction, leverage system, stable equilibrium, zero acc., high centre of gravity)

FOOT MOVEMENTS- foot moves towards the pitch of the ball.

(positive acc., negative acc, friction, impact-elasticity , spin, velocity)

DEFENCE- no gap between bat and pad, leg movements always along with the front foot, At the time of contact body weight shifted from heel to toe, simultaneously front foot knee slightly bend, back foot stretched.

(high cog, unstable equilibrium, friction, zero acceleration)

Vertical Bat Strokes Vertical bat or straight-bat shots can be

played either off the front foot or the back foot depending upon the anticipated height of the ball at the moment it reaches the batsman.

Defensive Shot Having taken a long stride, a batsman

blocks the ball with a forward defensive shot.

Horizontal Bat Shots The second class of cricket stroke are

the horizontal bat shots, also known as cross bat shots. These comprise the cut, the square drive, the pull, the hook and the sweep

FIELDING

CATCHING- Running towards the ball direction- (Speed, velocity, distance, friction,

linear kinematics) Eyes fix on ball-(velocity , power,

force, friction.)

GROUND FIELDING Moving quickly on the line of the ball (acc., friction, inertia of motion) Throwing (fluid mechanism, tailwind,

head wind, spin, parabola, projection, projectile, horizontal velocity.)

‘Natural Balance’ can involve controlling the body in a fixed position

(static balance),

STATIC & DYNAMIC BALANCE

and maintaining body control during movement (dynamic balance)

STABILITY PRINCIPLES

A body is balanced when its centre of gravity is vertically within its

base of support

Base of support

Centre of gravity outside base of support - fall over

A body loses balance when its centre of gravity is vertically outside its

base of support

STABILITY PRINCIPLES

Head to ball when stepping forward

Leaning forward to begin run up

MAINTAINING STABILITY – CONTROLLING DYNAMIC BALANCE

STABILITY - CONSEQUENCESBalance is affected when any body part is moved away from the centre of gravity

When balance is lost or affected a readjustments must occur ….. “WHAT DO YOU SEE ?”

“ACTION Vs REACTION”

WHAT DO YOU SEE ?

STABILITY A STABLE BASE produces POWER and CONTROL

The bat should start to move FORWARD only after the front/ back FOOT has made CONTACT with the GROUND

The legs remain BRACED to ensure maximum force generation

STABLE BASEA stable base ensures :

Head remains still, so eyes can see and focus Body is still and stronger and provides more resistance for POWER Energy is easily transferred into ACTION

LEVER ALIGNMENT

To maximise POWER and CONTROL all body levers (arms and legs) must move towards the target line

“Direct the energy / core of the body at the target”

BATTING

Keep bat and hands close to body Step towards target line Rotate shoulders and bat in the direction

of target Align front elbow and bat with the target Swing bat down target plane

BOWLING

Work arms and legs down target line Keep ball in close to body Drag front elbow down target line Rotate shoulders vertically towards target Follow through towards target

BALANCE & STABILITY - BATTINGSTANCE

The line of gravity is over the centre of the feet

ALIGNMENT

The base of support is aligned with the intended generation of force

THE STEPThe LOWER the centre of gravity, the GREATER the stability

The wider the base of support, the GREATER the stability

BALANCE & STABILITY - BATTING

LEVER ALIGNMENT - BATTING

It is important to align the body levers with the oncoming ball and choice of stroke (vertical or horizontal). This allows the player to hit the ball with POWER and CONTROL

BOWLING BOWLING :

To bowl / spin the ball fast (power)

land it where we want (control)

with the variations we want (control)

Spinners use shorter delivery stride lengths to increase height at release

Delivery strides too long - loss of height and leg collapse

BALANCE & STABILITY - BOWLING

LEVER ALIGNMENT - BOWLING

It is important to align all body levers toward the line of the target to ensure a balanced delivery. This allows the player to generate

POWER and CONTROL

Poor lever alignment produces inconsistent performances

FIELDING & WK

Fielding

To gather the ball cleanly (control) and throw it quickly

(power) and accurately (control)

Wicket Keeping

To catch the ball cleanly (control)

BALANCE & STABILITY – FIELDING & WK

Fielding requires a trade off between stable bases:

Movement towards the ball in a balanced position allows the player to move quickly in all directions

Base of support too narrow Base of support too wide

1-2 steps with the bowler Balanced “Step Jump” “Base Up”

THANK YOU