By: Samantha Stratford April 15th, 2013

OverviewFocus point of analysisInteresting factsThe 5 phases of movementWhat levers are used?3 Free body diagrams7 (5) principles of biomechanicsNewton’s lawsMax velocity and acceleration

Interesting FactsFreestyle was the first stroke to be

introduced in 1896,when swimming was first brought into the Olympics

Water is 73 times as dense as air and 55 times as viscous

Water’s buoyancy make swimming the ideal exercise for physical therapy and rehabilitation or for anyone seeking a low-impact exercise.

Focus Point of The Analysis:

The focus point of my analysis is the hand entry into the catch phase, then pull phase, finally the push/ finish phase and the recovery into the next cycle.

Description of movement: Set-upSet-up : Streamline and kickoutMuscles used:

Used to stabilize the body during the kickout: Rectus abdominus, transversus abdonimus, Internal obliques, external obliques

Used for hip abduction and extension during the kickout: Gluteus maximus, gluteus minimus, gluteus medius

Used for knee extension during dolphin kick: Vastus lateralis, Vastus intermedius, Vastus medialis, rectus femoris, Sartorius

Used for knee flexion during dolphin kick: Semimembranosous, semitendanosus, bicep femoris

Joints used: Hip joint (ball and socket), knee joint (hinge joint), ankle joint (synovial hinge joint)

Description of movement: Backswing

Backswing: Catch phaseMuscles used:

Used to stabilize the body during the stroke: Rectus abdominus, transversus abdominus, internal obliques, external obliques

Used for arm flexion to initiate catch: Brachialis, bicep brachii, flexors, extensors

Used for lateral arm rotation during the catch: Subscapularis, supraspinatus, infraspinatus, teres minor

Used for arm adduction in the middle of the catch: pectoralis minor, pectoralis major, latissimus dorsi, trapezius

Joints used: Shoulder joint (ball and socket), Wrist joint (condyloid)

Planes and axis: sagittal plane, antereoposterior axis, longitudinal axis

Description of movement: Force Movement

Force Movement: Underwater Pull/ pull phaseMuscles used:

Used to stabilize the body: Rectus abdominus, transversus abdominus, internal obliques, external obliques

Used for arm adduction during the start of the pull: Latissimus dorsi, trapezius, pectoralis major, pectoralis minor

Used for arm flexion and extension: Brachialis, bicep brachii, tricep brachii, flexors, extensors

Used for lateral rotation and retraction: rhomboids, subscapularis, supraspinatus, infraspinatus, teres minor

Joints used: shoulder joint (ball and socket), elbow joint (hinge), wrist (condyloid)

Planes and axis: saggital plane, antereopostierior axis, longitudinal axis

Description of movement: Critical Instant

Critical Instant: Finish PhaseMuscles Used:

Used to stabilize the body during the finish: rectus abdominus, transversus abdominus, internal obliques, external obliques

Used for arm flexion and extension: brachialis, bicep brachii, tricep brachii, extensors, flexors

Used for arm adduction: latissimus dorsi, trapezius, pectoralis major, pectoralis minor

Used for lateral rotation and retraction: rhomboids, subscapularis, supraspinatus, infraspinatus, teres minor

Joints used: Shoulder joint (ball and socket), elbow joint (hinge), wrist joint (condyloid)

Planes and axis: Saggital plane, antereoposterior axis, longitudinal axis

Description of movement: Follow Through

Follow through: RecoveryMuscles Used:

Used to stabilize the body: rectus abdominus, transverus abdominus, internal obliques, external obliques

Used for lateral rotation and retraction: subscapularis, supraspinatus, infraspinatus, teres minor, rhomboids

Used for arm abduction: deltoid(3), teres majorUsed for arm adduction: pectoralis minor, pectoralis

major, latissimus dorsi Joints used: shoulder joint (ball and socket), elbow joint

(hinge), wrist joint (condyloid) Planes and axis: transverse plane, saggital plane,

antereoposterior axis, longitudinal axis

What Levers are Used??First Class Lever:

This happens when the arms are at opposite ends of the body. One arm is starting the catch and the other is finishing the stroke.

Third Class Lever:• This happens when the bicep bends and extends to

initiate the catch phase of the stroke.

Free Body Diagrams

*all phases’ center of mass is the whole body because of the waters velocity which keeps the body in a floating position .•While swimming a person moves in the frontal and sagittal plane.•The swimmer is also on the antereoposterior axis

Principle 2: Maximum ForceProduction of maximum force requires the use of all

possible joint movements that contribute to the tasks movements. Maximum average propulsion force=average resistancePropulsion comes from the vector sum of lift and drag forces To propel forward we use multiple joints to contribute for the

maximum propulsion speed possible. We use our shoulder joint (ball and socket) which provides maximum

range possible so we can reach and get the maximum pull possible. We use our elbow joint (hinge) to initiate the pull phase of the stroke We use our ankle joint (condyloid) to propel ourselves forward with the

kick motion of our ankle joint. We use or hip joint (ball and socket) which is a multiaxial joint which

allows maximum range to help with the kick timing of the stroke and roll.

Principle 3: Maximum ForceThe production of maximum velocity requires the use of

joints and muscles in order from largest to smallest. During a freestyle stroke a swimmer uses their biggest

muscles to start the pull and the further you get down the stroke you use the smaller muscles groups.During the start of the stroke the swimmer initiates the

pull with the biggest muscles to apply maximum force. They use the deltoid , latissimus dorsi and rotator cuff.

The next phase of the stroke the swimmer uses the bicep brachii and brachialis

The next phase you start to use your tricep brachii , bicep brachii and latissimus dorsi

During the finish phase of the stroke you use you trip brachii and you felxor and extensors to finish the stroke and start the recovery

Principle 4: Linear MotionThe greater the applied impulse, the greater

the increase in velocity. The rate of change of the position of an

object increases when the swimmer applies more pressure on the catch and push phases of the stroke

The circled hand in this picture is the start of the push phase in the freestyle stroke.

Principle 5: Linear MotionMovement occurs in the direction opposite

than the applied force.Once the swimmer initiates the pull by rolling

their hips and utilizing the stabilizers of their torso they push the water backwards which results in forward motion. Once the one arm finishes the push phase and starts to recover the opposite arm begins to accelerate again.

Principle 6: Angular MotionProduced by the application of a force acting at some

distance from an axis by choice. This produces change in angular motion.

By initiating the roll with the hips the swimmer is using torque. The swimmers hips initiate the catch phase of the stroke because by rolling your hips you are twisting your body the opposite way of where your body would lie while completely relaxed.

Statistics show significant increase in torque production in swimmers for most motions tested. These shifts in the torque ratios in swimmers' shoulders resulted from sport-specific repetitive activity that emphasizes adduction and internal rotation.

Hip rotation occurs slightly before the shoulder rotation to place the trunk muscles in a stretch.

Principle 6 Cont’dAs the arm pulls back on the water, the hips rotate

to the opposite side to help pull the arm back. As trunk rotation stops, some of the angular

momentum of the trunk is transferred to the recovery arm to assist in optimizing recovery body position.

Newton’s 1st LawInertia: an object will remain in constant state unless

otherwise acted on. An object will move or continue to not move unless something else “makes” it.

This is true with a freestyle stroke because unless the recovery phase of the stroke is acted upon the swimmer will not move or accelerate any further.

Mass is the measure of inertia, therefore decreased mass in the water means faster acceleration rate speed ability.

Newton’s 2nd LawAcceleration: An object will continue at a

constant speed in a linear direction unless acted upon by an outside force.

The greater the applied force of the stroke the greater the resulting acceleration rate.

A person will remain in a linear direction at a constant speed while swimming unless acted upon. In this case the person would be acted upon by coming to a wall and having to start a flip turn to turn around.

Maximum AccelerationThe maximum acceleration rate in during the

21st frame at 5.067 seconds while the swimmer is ending the finish phase.

The person in my video is doing the stroke correctly because the finish phase is the strongest and most powerful phase of the whole stroke, therefore the maximum acceleration speed occurs in the proper place.

Velocity VS Time Graph

Questions??