Biomechanical Model Running.txt

*speed up*

A larger vertical ground reaction force creates greater friction force and greater total external force to push against. Greater external force to push against allows greater ankle plantar flexion muscle force, knee extension muscle force, and hip extension muscle force to be exerted. 

Greater ankle plantar flexion muscle force creates greater ankle plantar flexion joint torque and greater ankle plantar flexion angular velocity. Greater ankle plantar flexion angular velocity creates greater linear speed of the ankle and all joints superior to the ankle.

Greater knee extension muscle force creates greater knee extension joint torque and greater knee extension angular velocity. Greater knee extension angular velocity creates greater linear speed of the knee and all joints superior to the knee.

Greater hip extension muscle force creates greater hip extension joint torque and greater hip extension angular velocity. Greater hip extension angular velocity creates greater linear speed of the hip and all joints superior to the hip.

This coordinated increase in joint linear speeds is the result of modifying a factor that speeds the body up (vertical ground reaction force) and results in greater linear speed for the runner and a decrease in movement time.

to create a larger vertical ground reaction force you must run on the hardest surface available

*speed up*

A larger coefficient of friction creates greater friction force and greater total external force to push against. Greater external force to push against allows greater ankle plantar flexion muscle force, knee extension muscle force, and hip extension muscle force to be exerted.

Greater ankle plantar flexion muscle force creates greater ankle plantar flexion joint torque and greater ankle plantar flexion angular velocity. Greater ankle plantar flexion angular velocity creates greater linear speed of the ankle and all joints superior to the ankle.

Greater knee extension muscle force creates greater knee extension joint torque and greater knee extension angular velocity. Greater knee extension angular velocity creates greater linear speed of the knee and all joints superior to the knee.

Greater hip extension muscle force creates greater hip extension joint torque and greater hip extension angular velocity. Greater hip extension angular velocity creates greater linear speed of the hip and all joints superior to the hip.

This coordinated increase in joint linear speeds is the result of modifying a factor that speeds the body up (coefficient of friction) and results in greater linear speed for the runner and a decrease in movement time.

To create a larger coefficient of friction, the bottom surface of the shoes that you are wearing must have two characteristics:

(1) the material of the soles must be soft

(2) the surface of the soles must be rough

For the ankle muscle force box:

Greater ankle plantar flexion muscle force creates greater ankle plantar flexion joint torque and greater ankle plantar flexion angular velocity. Greater ankle plantar flexion angular velocity creates greater linear speed of the ankle and all joints superior to the ankle.

The increase in joint linear speeds superior to the ankle is the result of modifying a factor that speeds the body up (ankle plantar flexion muscle force) and results in greater linear speed for the runner and a decrease in movement time.

For the knee muscle force box:

Greater knee extension muscle force creates greater knee extension joint torque and greater knee extension angular velocity. Greater knee extension angular velocity creates greater linear speed of the knee and all joints superior to the knee.

The increase in joint linear speeds superior to the knee is the result of modifying a factor that speeds the body up (knee extension muscle force) and results in greater linear speed for the runner and a decrease in movement time.

For the hip muscle force box:

Greater hip extension muscle force creates greater hip extension joint torque and greater hip extension angular velocity. Greater hip extension angular velocity creates greater linear speed of the hip and all joints superior to the hip.

The increase in joint linear speeds superior to the hip is the result of modifying a factor that speeds the body up (hip extension muscle force) and results in greater linear speed for the runner and a decrease in movement time.

To create a larger muscle force, three factors that influence the size of the muscle force must be considered.

(1) muscle size (increase via training)

(2) muscle length (120% = most muscle force)

(3) speed of muscle contraction (contracted slower = more muscle force)

For the ankle moment arm box:

A longer ankle plantar flexion moment arm at the ankle joint creates greater ankle plantar flexion joint torque and greater ankle plantar flexion angular velocity. Greater ankle plantar flexion angular velocity creates greater linear speed of the ankle and all joints superior to the ankle.

The increase in joint linear speeds superior to the ankle is the result of modifying a factor that speeds the body up (ankle plantar flexion moment arm) and results in greater linear speed for the runner and a decrease in movement time.

For the knee moment arm box:

A longer knee extension moment arm at the knee joint creates greater knee extension joint torque and greater knee extension angular velocity. Greater knee extension angular velocity creates greater linear speed of the knee and all joints superior to the knee.

The increase in joint linear speeds superior to the knee is the result of modifying a factor that speeds the body up (knee extension moment arm) and results in greater linear speed for the runner and a decrease in movement time.

For the hip moment arm box:

A longer hip extension moment arm at the hip joint creates greater hip extension joint torque and greater hip extension angular velocity. Greater hip extension angular velocity creates greater linear speed of the hip and all joints superior to the hip.

The increase in joint linear speeds superior to the hip is the result of modifying a factor that speeds the body up (hip extension moment arm) and results in greater linear speed for the runner and a decrease in movement time.

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. This is not an option because 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.

*speed up*

For the ankle mass box:

A smaller body component mass superior to the ankle results in less angular inertia (i.e., less resistance to angular motion) for the body component. This will create greater ankle plantar flexion angular velocity. Greater ankle plantar flexion angular velocity creates greater linear speed of the ankle and all joints superior to the ankle.

The increase in joint linear speeds superior to the ankle is the result of modifying a factor that speeds the body up (body component mass superior to the ankle) and results in greater linear speed for the runner and a decrease in movement time. 

For the knee mass box:

A smaller body component mass superior to the knee results in less angular inertia (i.e., less resistance to angular motion) for the body component. This will create greater knee extension angular velocity. Greater knee extension angular velocity creates greater linear speed of the knee and all joints superior to the knee.

The increase in joint linear speeds superior to the knee is the result of modifying a factor that speeds the body up (body component mass superior to the knee) and results in greater linear speed for the runner and a decrease in movement time.

For the hip mass box:

A smaller body component mass superior to the hip results in less angular inertia (i.e., less resistance to angular motion) for the body component. This will create greater hip extension angular velocity. Greater hip extension angular velocity creates greater linear speed of the hip and all joints superior to the hip.

The increase in joint linear speeds superior to the hip is the result of modifying a factor that speeds the body up (body component mass superior to the knee) and results in greater linear speed for the runner and a decrease in movement time.

Short-term for body component mass

(1) wear the lightest clothing possible

(2) wear the lightest shoes possible

Long-term for body component mass

(1) lose fat mass

For the ankle radius of resistance:

A shorter radius of resistance for the body component mass superior to the ankle results in less angular inertia (i.e., less resistance to angular motion) for the body component. This will create greater ankle plantar flexion angular velocity. Greater ankle plantar flexion angular velocity creates greater linear speed of the ankle and all joints superior to the ankle.

The increase in joint linear speeds superior to the ankle is the result of modifying a factor that speeds the body up (radius of resistance of the body component mass superior to the ankle) and results in greater linear speed for the runner and a decrease in movement time.

For the knee radius of resistance box:

A shorter radius of resistance for the body component mass superior to the knee results in less angular inertia (i.e., less resistance to angular motion) for the body component. This will create greater knee extension angular velocity. Greater knee extension angular velocity creates greater linear speed of the knee and all joints superior to the knee.

The increase in joint linear speeds superior to the knee is the result of modifying a factor that speeds the body up (radius of resistance of the body component mass superior to the knee) and results in greater linear speed for the runner and a decrease in movement time.

For the hip radius of resistance box:

A shorter radius of resistance for the body component mass superior to the hip results in less angular inertia (i.e., less resistance to angular motion) for the body component. This will create greater hip extension angular velocity. Greater hip extension angular velocity creates greater linear speed of the hip and all joints superior to the hip.

The increase in joint linear speeds superior to the hip is the result of modifying a factor that speeds the body up (radius of resistance of the body component mass superior to the hip) and results in greater linear speed for the runner and a decrease in movement time.

The distance from the joint's axis of rotation to the center of mass of the body component.

The length of the radius of resistance is determined by bone length and joint orientation. There is nothing we can do to decrease bone length.

However, similar to changing the moment arm distance, we can shorten the radius of resistance by changing the angles of the joints with the body component being rotated.

Any change in a joint angle that brings a portion of the body component closer to the axis of rotation will shorten the radius of resistance.

For the ankle application time of joint torque box:

A longer application time of the ankle plantar flexion joint torque will create greater ankle plantar flexion angular velocity. Greater ankle plantar flexion angular velocity creates greater linear speed of the ankle and all joints superior to the ankle. 

The increase in joint linear speeds superior to the ankle is the result of modifying a factor that speeds the body up (application time of the ankle plantar flexion joint torque) and results in greater linear speed for the runner and a decrease in movement time.

For the knee application time of joint torque box:

A longer application time of the knee extension joint torque will create greater knee extension angular velocity. Greater knee extension angular velocity creates greater linear speed of the knee and all joints superior to the knee.

The increase in joint linear speeds superior to the knee is the result of modifying a factor that speeds the body up (application time of the knee extension joint torque) and results in greater linear speed for the runner and a decrease in movement time.

For the hip application time of joint torque box:

A longer application time of the hip extension joint torque will create greater hip extension angular velocity. Greater hip extension angular velocity creates greater linear speed of the hip and all joints superior to the hip.

The increase in joint linear speeds superior to the hip is the result of modifying a factor that speeds the body up (application time of the hip extension joint torque) and results in greater linear speed for the runner and a decrease in movement time.

For the ankle:

(1) During the preparation phase, the ankle must be dorsiflexed

(2) During the execution phase, a concentric ankle plantar flexion joint torque is applied until the ankle is maximally plantar flexed

For the knee:

(1) During the preparation phase, the knee must be flexed

(2) During the execution phase, a concentric knee extension joint torque is applied until the knee is maximally extended

For the hip:

(1) During the preparation phase, the hip must be flexed

(2) During the execution phase, a concentric hip extension joint torque is applied until the hip is maximally extended

For the ankle radius of rotation box:

A longer radius of rotation for the body component superior to the ankle joint creates greater linear speed of the ankle and all joints superior to the ankle.

The increase in joint linear speeds superior to the ankle is the result of modifying a factor that speeds the body up (radius of rotation for the body component superior to the ankle) and results in greater linear speed for the runner and a decrease in movement time.

For the knee radius of rotation box:

A longer radius of rotation for the body component superior to the knee joint creates greater linear speed of the knee and all joints superior to the knee.

The increase in joint linear speeds superior to the knee is the result of modifying a factor that speeds the body up (radius of rotation for the body component superior to the knee) and results in greater linear speed for the runner and a decrease in movement time.

For the hip radius of rotation box:

A longer radius of rotation for the body component superior to the hip joint creates greater linear speed of the hip and all joints superior to the hip.

The increase in joint linear speeds superior to the hip is the result of modifying a factor that speeds the body up (radius of rotation for the body component superior to the hip) and results in greater linear speed for the runner and a decrease in movement time.

The distance from the joint's axis of rotation to the point of interest on the body component.

The length of the radius of rotation is determined by bone length and joint orientation. There is nothing we can do to increase bone length.

However, similar to changing the moment arm and the radius of resistance, 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.

A decrease in fluid density would decrease the drag force on the body as it moves through the fluid. This would decrease the external forces slowing the body down and would decrease the sum of joint forces that the body must absorb.

The decrease in the sum of joint forces that the body must absorb is the result of modifying a factor that slows the body down (fluid density) and results in less slowing down of the body. This would make it easier to maintain a greater linear speed and would result in a decrease in movement time.

During running, the fluid you are moving through is air.

There are three atmospheric conditions that would reduce fluid density:

(1) higher altitude

(2) lower humidity

(3) warmer temperatures

A decrease in the coefficient of drag would decrease the drag force on the body as it moves through the fluid. This would decrease the external forces slowing the body down and would decrease the sum of joint forces that the body must absorb.

The decrease in the sum of joint forces that the body has to absorb is the result of modifying a factor that slows the body down (coefficient of drag) and results in less slowing down of the body. This would make it easier to maintain a greater linear speed and would result in a decrease in movement time.

A measure of the surface friction between the surface of the runner and the air as the runner moves through the air.

The coefficient of drag may be reduced by making the surface of the runner smoother.

This can be accomplished in 3 ways:

(1) any clothes that are worn must be made of materials that are extremely smooth

(2) worn clothes must be tight-fitting

(3) uncovered areas of the body should have the body hair removed

A decrease in the area of drag would decrease the drag force on the body as it moves through the fluid. This would decrease the external forces slowing the body down and would decrease the sum of joints force that the body must absorb.

The decrease in the sum of joint forces that the body has to absorb is the result of modifying a factor that slows the body down (area of drag) and results in less slowing down of the body. This would make it easier to maintain a greater linear speed and would result in a decrease in movement time.

A measure of the area of turbulent air behind the runner as the runner moves through the air.

The area of drag may be reduced by making the area of turbulent air behind the runner smaller.

There are 2 primary mechanisms for reducing the area of turbulent air behind the runner:

(1) make the area of the runner that collides with the air smaller

(2) have the runner run in an aerodynamic position

Unfortunately, neither of these 2 mechanisms can be implemented during running.

The primary method for making the area that collides with the air smaller is to reduce the height and weight of the runner. Doing either of these would affect the speeding up side of the model.

For these reasons, nothing can be done to reduce the area of drag during running.

A decrease in relative velocity would decrease the drag force on the body as it moves through the fluid. This would decrease the external forces slowing the body down and would decrease the sum of joint forces that the body must absorb.

The decrease in the sum of joint forces that the body has to absorb is the result of modifying a factor that slows the body down (relative velocity) and results in less slowing down of the body. This would make it easier to maintain a greater linear speed and would result in a decrease in movement time.

A measure of the speed and direction of the air that is colliding with your body.

There are two approaches to reducing relative velocity.

(1) run on days when there is little or no wind

(2) use a movement technique called "drafting"

-following runner experiences smaller drag forces = energy efficiency

*slow down*

A decrease in the vertical ground reaction force would decrease the friction force and decrease the external forces slowing the body down. This would decrease the sum of joint forces that the body must absorb.

The decrease in the sum of joint forces that the body has to absorb is the result of modifying a factor that slows the body down (vertical ground reaction force) and result in less slowing down of the body. This would make it easier to maintain a greater linear speed and would result in a decrease in movement time.

There are 2 methods for reducing the magnitude of the vertical ground reaction force on the slowing down side of the model.

(1) create a smaller body component mass

• -short term: wearing the lightest clothing and shoes possible
• -long term: changing body composition/loss of fat mass

(2) increase the application time of the vertical ground reaction force when the body collides with the ground

*slow down*

A decrease in the coefficient of friction would decrease the friction force and decrease the external forces slowing the body down. This would decrease the sum of joint forces that the body must absorb.

The decrease in the sum of joint forces that the body has to absorb is the result of modifying a factor that slows the body down (coefficient of friction) and results in less slowing down of the body. This would make it easier to maintain a greater linear speed and would result in a decrease in movement time.

Theoretically, we could make the material of the shoe harder and the surface of the material smoother. This would decrease the magnitude of the friction force that slows you down.

Unfortunately, the real-world application is something very different.

Decreasing the coefficient of friction is not an option because it will have no affect on the magnitude of the friction force slowing you down until you reduce it to a level that would allow the shoe to slip.

A decrease in the application time of the external forces that slow the body down would decrease the sum of joint forces that the body must absorb.

The decrease in the sum of joint forces that the body has to absorb is the result of modifying a factor that slows the body down (application time of each external force that slows the body down) and results in less slowing down of the body. This would make it easier to maintain a greater linear speed and would result in a decrease in movement time.

The most effective method to decrease the application time of the friction force is to land with your foot underneath your center of mass.

4 real-world actions must be performed in order to increase the application time of the external forces slowing the body down:

(1) initial contact must be on the forefoot

(2) the ankle joint should be slightly plantar flexed prior to contact with the ground and then upon contact with the ground, the ankle plantar flexor muscles should be contracted to create an eccentric ankle dorsiflexion torque

(3) the knee joint should be slightly flexed prior to contact with the ground

(4) the hip joint should be slightly flexed prior to contact with the ground

for the drag force, there is nothing that can be done to reduce the application time

*slow down*

An increase in the body's mass would decrease the effectiveness of any external forces that slow the body down.

The decreased effectiveness of external forces to slow the body down is the result of modifying a factor that slows the body down (body mass) and results in less slowing down of the body. This would make it easier to maintain a greater linear speed and would result in a decrease in movement time.

Theoretically, increasing the mass would be an effective method to reduce how much 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 propel ourselves forward. 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.

A decrease in the distance traveled would result in a decrease in movement time.

This concept should not be taken literally. it does not mean run a shorter distance.

Instead, its meaning is that if you are planning to run for a 5K race, then only run 5000 meters. Do not run 5001, 5010, or 5020 meters. How is this accomplished?

There are 2 specific rules:

(1) when the road or path is curved, run close to the curve

(2) run in a straight line from curve to curve