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Understanding Levers and Their Role in Physical Activity and Sports Performance, Schemes and Mind Maps of Dance

University of Connecticut (UConn) - Avery Point Dance

An introduction to levers, their classes, and their impact on sports performance. Learn about first, second, and third class levers, mechanical advantage and disadvantage, and planes and axes of movement. Useful for students studying kinesiology, exercise science, or sports performance.

What you will learn

What are the planes and axes of movement and how are they applied to sports?
What are the three classes of levers and how do they differ?
How does mechanical advantage or disadvantage affect sports performance?

Typology: Schemes and Mind Maps

2021/2022

Uploaded on 09/27/2022

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Don't miss anything!

When you have worked through this chapter, you will have developed

a knowledge and understanding of:

● fi rst, second and third class levers and their use in physical activity

● mechanical advantage and disadvantage of the body’s lever systems

and the impact this has on sporting performance

● planes and axes of movement applied to sporting actions.

Movement analysis

837021_ch02.indd 47 02/02/16 5:04 PM

Partial preview of the text

Download Understanding Levers and Their Role in Physical Activity and Sports Performance and more Schemes and Mind Maps Dance in PDF only on Docsity!

When you have worked through this chapter, you will have developed

a knowledge and understanding of:

● first, second and third class levers and their use in physical activity

● mechanical advantage and disadvantage of the body’s lever systems

and the impact this has on sporting performance

● planes and axes of movement applied to sporting actions.

Movement analysis

2.1 Levers

Levers are seen in everyday life as well as in sport and exercise. A lever system

is a rigid bar that moves around a fixed fulcrum with two forces applied to it.

Levers can change the size or direction of the effort used to make a task more

manageable.

All levers consist of three key elements:

1 Fulcrum: a fixed pivot point.

2 Effort: the source of the energy that will do the work.

3 Load: the weight/resistance to be moved.

Activity

The picture shows how a lever can be useful. a) Explain how this lever works and what advantage a person gains using a lever in this situation. b) Can you identify the fulcrum, effort and load in the picture?

Key terms

Lever: A rigid bar or object that moves around a fixed fulcrum with two forces applied to it. Fulcrum: A fi xed pivot point. For example, a joint in the body. Effort: The source of the energy. For example, muscles in the body. Load: The weight/resistance to be moved. For example, a body part plus anything held or resistance met.

Key term

Class of lever: The type of lever. There are fi rst class, second class and third class levers.

Exam tip

You will be expected to draw and label simple lever set-ups, so you’ll need a method for remembering the difference between fi rst, second and third class levers.

Try imagining: one see-saw, two wheelbarrows and three fi shing rods.

Or use the mnemonic “1, 2, 3, F, L, E” to help you remember the middle element of each class of lever.

First, second and third class levers

There are three classes of lever: first class levers, second class levers and third

class levers. The positioning of the fulcrum, load and effort in relation to each

other will determine what class the lever is.

In the human body, the musculo-skeletal system creates levers around every

joint. These allow us to move. The joint acts as the fulcrum, effort comes from

contracting muscles and the load is the body part being moved, plus any

additional objects held or resistance met. The body contains all classes of lever,

but third class levers are most common.

There are two main benefits of lever systems:

1 Large loads can be moved with a relatively small amount of effort.

2 The distance a load can be moved, or the speed with which it can be

moved, can be increased without an increase in effort.

To work out the benefit of a particular lever, you need to look at the length of

two arms. The distance from the load to the fulcrum is known as the load arm,

while the distance from the effort to the fulcrum is known as the effort arm.

2.2 The benefi ts of different levers

Key terms

Load arm: The distance from the load to the fulcrum. Effort arm: The distance from the effort to the fulcrum.

Key term

Mechanical advantage: Second class levers allow a large load to be moved with a relatively small amount of muscular effort.

Fulcrum

Load Effort

Fulcrum

Effort

Load

Activity

4 Draw a simple diagram of each of the three lever classes and label the effort arm and load arm. Here is an example of a first class lever to show you how this is done.

Mechanical advantage and disadvantage

Mechanical advantage

When a lever’s effort arm is longer than its load arm it is said to have

mechanical advantage. Levers with mechanical advantage can move large

loads with a relatively small amount of effort. They have a high load force to

effort ratio. Second class levers always have mechanical advantage.

If we consider a long jumper taking off, we see how the second class lever,

where the foot contacts the ground, has a high mechanical advantage because

the effort arm is longer than the load arm. The result of this, for the long

jumper, is that the force produced by the muscles, which is relatively small, is

able to drive the full weight of the athlete off the ground.

Fulcrum

Load arm Effort arm

Effort

Load

Mechanical disadvantage

When a lever’s load arm is longer than its effort arm, it is said to be at a

mechanical disadvantage. It has a low load force to effort ratio. Third class

levers always have mechanical disadvantage.

Despite operating at mechanical disadvantage, third class levers are able to

increase the distance covered and, therefore, the speed at the end of a lever

arm. They can produce a larger range of movement with relatively low effort.

The hip joint is a third class lever. It cannot produce the same load force to

effort ratio as a second class lever. However, this doesn’t mean that it is not

good at what it does. Third class levers can take a small movement near

the fulcrum and make a large movement where the load is. This provides a

relatively large range of movement, which results in relatively high speed

being produced.

Key term

Mechanical disadvantage: Third class levers cannot lift such heavy loads, with the same amount of effort, as second class levers due to the position of the fulcrum in relation to the effort and load.

First class levers: mechanical advantage and disadvantage

In the case of first class levers, the position of the fulcrum is key. If the fulcrum

is closer to the load, then relatively low effort will result in larger, more powerful

movements at the load end; there will be mechanical advantage. If the fulcrum

is closer to the effort, then the lever will operate at mechanical disadvantage

but will produce a larger range of movement at the end of the lever and

greater speed as a result.

Load Load Fulcrum

Effort

Fulcrum

Effort

Activity

(^5) a) Look at these rowers and discuss the class of lever that the oars create. b) What is the benefit of this lever system to the rowers’ performance?

2 Movement analysis2 Movement analysis

By looking at the diagrams and photographs together, we can see that:

● A cartwheel in gymnastics or dance takes place in the frontal plane around

the sagittal axis.

● A full twist jump in trampolining takes place in the transverse plane around

the vertical axis.

● A somersault in gymnastics or diving (front/back and piked/tucked) takes

place in the sagittal plane around the frontal axis.

Key terms

Frontal plane: An imaginary line dividing the body vertically from front to back. Sagittal plane: An imaginary line dividing the body vertically into left and right sides. Transverse plane: An imaginary line dividing the body horizontally from front to back. Frontal axis: An imaginary line passing horizontally through the body from left to right, allowing fl exion and extension. Sagittal axis: An imaginary line passing horizontally through the body from front to back, allowing abduction and adduction. Vertical axis: An imaginary line passing vertically through the body, allowing rotation of the body in an upright position.

The sagittal plane divides the body vertically into left and right sides. Movement occurs in the sagittal plane about the frontal axis. The frontal axis passes horizontally through the body from left to right, allowing flexion and extension.

Activity

6 a) Make a model of a person standing in the anatomical position from Plasticine or Play-Doh. Use a pencil as an axis and two pieces of card as a plane. Push your pencil through your model and attach a piece of card to either side to represent the corresponding plane. If you spin your pencil, the model will rotate around that axis and in line with the plane. b) Can you think of other sporting actions that take place in the planes and around the axes described on these two pages? They can be whole body movements or movements that involve only part of the body. c) Use your model to make a video presentation explaining planes and axes, using the examples you came up with for part b.

Exam tip

A wheel on a bike spins around a central axle. This is how an axis works. If you had an axis through your belly button, you’d spin like a wheel. Think of a plane as a thick sheet of glass that you’re trapped tightly inside. Movements that take place in that plane can only occur in the direction that the sheet of glass allows.

Understanding Levers and Their Role in Physical Activity and Sports Performance, Schemes and Mind Maps of Dance

Related documents

Partial preview of the text

Download Understanding Levers and Their Role in Physical Activity and Sports Performance and more Schemes and Mind Maps Dance in PDF only on Docsity!

When you have worked through this chapter, you will have developed

a knowledge and understanding of:

● first, second and third class levers and their use in physical activity

● mechanical advantage and disadvantage of the body’s lever systems

and the impact this has on sporting performance

● planes and axes of movement applied to sporting actions.

Movement analysis

Levers are seen in everyday life as well as in sport and exercise. A lever system

is a rigid bar that moves around a fixed fulcrum with two forces applied to it.

Levers can change the size or direction of the effort used to make a task more

manageable.

All levers consist of three key elements:

1 Fulcrum: a fixed pivot point.

2 Effort: the source of the energy that will do the work.

3 Load: the weight/resistance to be moved.

There are three classes of lever: first class levers, second class levers and third

class levers. The positioning of the fulcrum, load and effort in relation to each

other will determine what class the lever is.

In the human body, the musculo-skeletal system creates levers around every

joint. These allow us to move. The joint acts as the fulcrum, effort comes from

contracting muscles and the load is the body part being moved, plus any

additional objects held or resistance met. The body contains all classes of lever,

but third class levers are most common.

There are two main benefits of lever systems:

1 Large loads can be moved with a relatively small amount of effort.

2 The distance a load can be moved, or the speed with which it can be

moved, can be increased without an increase in effort.

To work out the benefit of a particular lever, you need to look at the length of

two arms. The distance from the load to the fulcrum is known as the load arm,

while the distance from the effort to the fulcrum is known as the effort arm.

When a lever’s effort arm is longer than its load arm it is said to have

mechanical advantage. Levers with mechanical advantage can move large

loads with a relatively small amount of effort. They have a high load force to

effort ratio. Second class levers always have mechanical advantage.

If we consider a long jumper taking off, we see how the second class lever,

where the foot contacts the ground, has a high mechanical advantage because

the effort arm is longer than the load arm. The result of this, for the long

jumper, is that the force produced by the muscles, which is relatively small, is

able to drive the full weight of the athlete off the ground.

When a lever’s load arm is longer than its effort arm, it is said to be at a

mechanical disadvantage. It has a low load force to effort ratio. Third class

levers always have mechanical disadvantage.

Despite operating at mechanical disadvantage, third class levers are able to

increase the distance covered and, therefore, the speed at the end of a lever

arm. They can produce a larger range of movement with relatively low effort.

The hip joint is a third class lever. It cannot produce the same load force to

effort ratio as a second class lever. However, this doesn’t mean that it is not

good at what it does. Third class levers can take a small movement near

the fulcrum and make a large movement where the load is. This provides a

relatively large range of movement, which results in relatively high speed

being produced.

In the case of first class levers, the position of the fulcrum is key. If the fulcrum

is closer to the load, then relatively low effort will result in larger, more powerful

movements at the load end; there will be mechanical advantage. If the fulcrum

is closer to the effort, then the lever will operate at mechanical disadvantage

but will produce a larger range of movement at the end of the lever and

greater speed as a result.

2 Movement analysis2 Movement analysis

By looking at the diagrams and photographs together, we can see that:

● A cartwheel in gymnastics or dance takes place in the frontal plane around

the sagittal axis.

● A full twist jump in trampolining takes place in the transverse plane around

the vertical axis.

● A somersault in gymnastics or diving (front/back and piked/tucked) takes

place in the sagittal plane around the frontal axis.

1 Which one of the following describes a third class

lever? (1)

A The load is to the right of the fulcrum

B The effort is in the middle of the lever

C The load is in the middle of the lever

D The fulcrum is on the left of the lever

2 Which one of the following is an example of a first

class lever? (1)

A A car jack

B A nutcracker

C A wheelbarrow