Real-World: Swimming

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1. Coefficient of Drag
*speed up*

A measure of the surface friction between the water and the surfaces of the swimmer's hand as the swimmer's hand moves through the water.

The coefficient of drag may be increase by making the surface of the swimmer's hand rougher.

-no methods for increasing hand roughness

-swimming glove that has a surface rougher than the hand's natural surface could be designed
2. Area of Drag
*speed up*

A measure of the area of turbulent water behind the anterior surface of the swimmer's hand as the hand moves backward (superior to inferior) through the water.

The area of drag may be increased by making the area of turbulent water behind the anterior surface of the swimmer's hand larger. The method for this is to increase the size of the hand. This can be accomplished by wearing a hand device that increase the size of the hand.

An additional method would be to spread the fingers apart. Care must be taken to not spread the fingers too far apart. The optimal distance is wide enough the water does not flow between the fingers.
3. Fluid Density
*speed up*

There are two fluid conditions that would change the density of water:

(1) water temperature (warmer water = density reduced)

(2) water type (fresh water = density reduced)

Therefore, greater fluid density occurs when two conditions occur:

(1) the water is colder

(2) the water has more sodium

Reduced fluid density occurs when:

(1) the water is warmer

(2) the water has less sodium

These conditions are not modifiable by the performer.
4. Relative Velocity
*speed up*

A measure of the speed and direction of the water that is colliding with your hand.

To increase relative velocity, the hand must move through the water very quickly. Moving the hand quickly must not be performed by sacrificing the area of drag for the area of lift.

A quickly moving hand with small areas of drag and lift creates very little drag and lift force.

The hand must move quickly while maintaining maximum areas of drag and lift.
5. Area of Lift
A measure of the area of the hand that is perpendicular to the motion of the hand as it moves laterally through the water.

The anterior surface of the swimmer's hand should be as large as possible.

To create a lift force, the hand must move perpendicularly to the direction of motion (medial to lateral or lateral to medial) as the hand moves backward (superior to inferior) through the water.

This perpendicular movement is created by elbow flexion and extension as the shoulder adducts.
6. Coefficient of Lift
A measure of the hands ability to create lift as it moves through the water.

The coefficient of lift may be increased in three ways:

(1) make hand have an airfoil shape

-the hand should be slightly cupped

-will create a lift force as the hand moves through the water

(2) have the hand spin

(3) increase the angle of attack as the hand moves through the water

-forearm must be supinated as the elbow flexes and then pronated as the elbow extends

-will create the proper angle of attack to create a lift force as the hand moves through the water

Of these three methods, only the first and the third methods can be used.
7. Muscle Force
To create a larger muscle force, three factors that influence the size of the muscle force must be considered.

(1) Muscle Size

-a muscle with a larger physiological cross-sectional area will create more muscle force

-increase via resistance training

(2) Muscle Length

-muscles stretched to 120% of their natural resting length generate the most muscle force

(3) Speed of the Muscle Contraction

-muscles that are concentrically contracted at slower speeds generate greater muscle force than muscles that are concentrically contracted at faster speeds
8. Moment Arm
The distance from the joint's axis of rotation to the line of pull of the muscle force.

To increase the moment arm distance, you would need to move the line of pull of the muscle force further away from the joint's axis of rotation.

One method for moving the line of pull of the muscle force would be to change the locations of the origin and insertion points for the muscle. It would be unethical to perform this type of surgery.

The only way we can change the moment arm distance is by changing the angle of the joint. When the long axes of the two bones connected at a joint are aligned long axis to long axis (straight line), the moment arm distance is the smallest.
9. Mass
*speed up*

SHORT-TERM

(1) wear the lightest clothing possible

(2) wear the lightest shoes possible

LONG-TERM

-lose fat mass
10. Radius of Resistance
The distance from the joint's axis of rotation to the center of mass of the body component.

Individuals with shorter bones will have shorter radii of resistance. There is nothing we can do to decrease bone length.

We can change the radius of resistance by changing the angles of the joints within the body component being rotated. We can decrease the radius of resistance by rotating the body component closer to the joint axis of rotation.
11. Application Time of Each Muscle Torque
AT THE SHOULDER:

-during the execution phase, a concentric shoulder adduction joint torque is applied until the shoulder is maximally adducted

AT THE ELBOW:

-during the execution phase, a concentric elbow flexion joint torque is applied until the elbow is maximally flexed

-during the execution phase, a concentric elbow flexion joint torque is applied until the elbow is maximally extended

AT THE WRIST:

-during the execution phase, a concentric wrist flexion joint torque is applied until the wrist is maximally flexed
12. Radius of Rotation
The distance from the joint's axis of rotation to the point of interest on the body component.

Individuals with longer bones will have longer radii of resistance. There is nothing we can do to increase bone length.

We can change the radius of rotation by changing the angles of the joints within the body component being rotated. Any change in a joint angle that rotates a portion of the body component farther from the axis of rotation will lengthen the radius of rotation.
13. Fluid Density
*slow down*

There are two fluid conditions that would change the density of water:

(1) water temperature (warmer water = density reduced)

(2) water type (fresh water = density reduced)
14. Coefficient of Drag
*slow down*

A measure of the surface friction between the water and the surfaces of the swimmer's body.

The coefficient of drag may be INCREASED by making the surface of the swimmer's foot rougher.

-no methods for increasing foot roughness

-swimming shoe that has a surface rougher than the foot's natural surface could be designed

The coefficient of drag may be DECREASED by making the surface of the swimmer's body smoother.

For the swimmer, this is accomplished in 3 ways:

(1) the swimsuit must be made of materials that are extremely smooth

(2) the swimsuit must be tight-fitting

(3) any uncovered areas of the body should have body hair removed
15. Area of Drag
*slow down*

A measure of the area of turbulent water behind the swimmer's foot as the foot moves up and down through the water.

There is one mechanism for increasing the area of turbulent water behind the swimmer's foot: make the area of the foot that collides with the water larger.

The method for making the area of the foot that collides with the water larger is to increase the size of the foot. That can be accomplished by wearing a foot device that increase the size of the foot. Diving flippers area a good example of a foot device that increases the area of drag.
16. Relative Velocity
*slow down*

A measure of the speed and direction of the water that is colliding with your foot or body.

There are two approaches to reducing relative velocity:

(1) swim in bodies of water that have no current (swimming pools/fresh water lakes)

-when you swim with a current, your relative velocity is reduced

(2) use a movement technique called "drafting"

-following swimming experiences a smaller drag force

-less energy expenditure (can lead to finishing swim with a short duration sprint around lead swimmer)
17. Body Density
To increase the buoyant force, the overall body density must be reduced compared to the density of the water.

There are two mechanism that can be used:

(1) remove body components or materials that have densities greater than the density of water

(2) add body components or material that have densities less than the density of water

ALSO:

To reduce body density relative to water density, you would need to lose muscle mass and/or increase fat mass. This would never be a recommendation. Thus, there is nothing you can do to remove or add body components that will decrease your body density.

You could wear swim clothing that has a density less than the density of water. One example is a wetsuit. If thrown in water, a wetsuit will float. This demonstrates that it has a density less than water. Therefore, if you swim wearing a wetsuit, you will decrease your body density relative to water density.
18. Application Time of Each External Force
Decreasing the application time of the only external force that is slowing the body down, the drag force, would be a major mechanism for reducing the magnitude of the internal forces the body must absorb.

Unfortunately, there is nothing that can be done to reduce this application time. If the swimmer is moving, a drag force will oppose the motion and slow the body down.
19. Mass
*slow down*

Theoretically, increasing the mass would be an effective method to reduce how quickly you slow down.

Unfortunately, a larger mass is more difficult to move quickly. There is a mass concept box on the speeding up side of the model; and the interpretation for that box was that the mass must be small if we want to effectively speed the body up.

These two interpretations conflict. However, the logic should be easy to see. We need to get the body moving quickly each time we pull ourselves forward through the water. This requires the mass be as small as we can make it. There is no way to simultaneously increase the mass so that we don't slow down as much.
20. Distance
Unlike running and road cycling, swimming generally is performed following a straight path.

In a pool, you swim down a length of the pool. You turn around and then swim back a length of the pool.

There is no curve. In open water swimming, there is a starting point and ending point. You swim from the start to the end. Again, there are no curves. Thus, the only way to minimize the distance is to swim as straight a line as possible.
 Author: Anonymous ID: 248229 Card Set: Real-World: Swimming Updated: 2013-11-21 06:48:44 Tags: THESE ARE DONE Folders: Description: THESE ARE DONE Show Answers: