First BPTh (Physiotherapy)

1. LEVERS
Dr Samiksha Sanjiv Sathe
Assistant Professor, Department of Musculoskeletal
Physiotherapy
Datta Meghe College of Physiotherapy, Wanadongari
Nagpur
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2. LEVERS 2
DEPARTMENT OF
MUSCULOSKELETAL
PHYSIOTHERAPY
DATTA MEGHE COLLEGE OF
PHYSIOTHERAPY

3. • This power point presentation has been prepared keeping in mind the First
BPTh University exam going students
• The purpose of the presentation is to understand the concept of LEVERS as
well as to use and apply the gained knowledge in clinical practice
• An attempt has been done to cover maximum aspects of Levers, but despite all
efforts the presentation may have some lacunae
• I am grateful to all those who have helped me
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Preface
Dr Samiksha Sathe
(MPT Orthopedic Physiotherapy)

4. LEVERS 4
Contents
Sr No Topic Slide no
1 Introduction 8-10
2 Orders or Classes of Lever 11-14
3 Features Of Lever 15
4 Mechanical Advantage 16-19
5 Levers in Human Body 20-26
6 Levers in Physiotherapy 27-29
7 References 30

5. General Objectives of the Syllabus
• At the end of the session student should be able to understand –
 The definition and Orders of Levers
 Levers in Human body
 The application and use of Levers in Physiotherapy treatment
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6. Objectives
• Upon completion of the lecture student should be able to explain –
 What is LEVER
 Orders of LEVER
 Features of LEVER
 Mechanical Advantage
 LEVERS in Human Body
 LEVERS in Physiotherapy
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7. LEVERS 7
Sr.no. Learning objectives Domain Level Criteria
1 Explain Orders of Lever Cognitive Must know All
2 Explain Mechanical
Advantage
Cognitive &
Psychomotor
Must know All
3 Explain levers in Human
body
Cognitive &
Psychomotor
Must know All
4 Explain application and
use of Levers in
Physiotherapy treatment
Cognitive &
Psychomotor
Must know All
Learning Objectives

8. LEVER
• A lever is a rigid bar which is capable of movement about a fixed point called a
fulcrum (f) (1)
• Parts of Lever -
 Fulcrum (F)
 Weight's arm (WA)
 Efforts Arm (EA)
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1. Gardiner DM. The Principles of Exercise Therapy. 4th ed. India: CBS;2005

9. • Force or effort (E) applied on one point of lever acting on another force or weight
(W) applied at the second point on the lever results in Work
• Effort's Arm is the distance between the fulcrum and the point at which effort is
being applied
• Weight's Arm is the distance between the fulcrum and the point at which Weight is
being applied
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10. • In human body, bone (rigid bar) being capable of movement about a fixed point
(fulcrum - joint) represents the lever
• For work to be done, the force of muscular contraction provides the effort which
is applied at the point of insertion to the bone
• The centre of gravity of the part to be moved or of the object to be lifted provides
the weight or load.
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11. Orders or Classes of Levers
There are Three Orders or Classes of Levers
The order depends on the respective positions of the fulcrum, effort and
weight
 1nd Order Lever
 2nd Order Lever
 3rd Order Lever
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12. • 1st Order
 In First Order Lever the fulcrum lies is between the effort and the weight, it may lie at
the centre or either towards the weight or the effort.
 Therefore, the weight's and the effort's arms may be of equal length or one may exceed
the other in length.
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13. 2nd Order
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In Second Order Lever the weight lies is between the fulcrum and the effort.
 Therefore, the effort's arm always exceeds the weight's arm

14. 3rd Order
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 In Third Order Lever the effort lies is between the fulcrum and the weight
 Therefore, the weight's arm always exceeds the effort's arm

15. FEATURES OF LEVER
1ST ORDER – STABILITY
2ND ORDER – POWER
3RD ORDER – VELOCITY
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16. MECHANICAL ADVANTAGE
•Mechanical advantage is the ratio of the weight to the effort
• Mechanical Advantage = W/E
• The MA equals to 1 when the weight and effort are of equal magnitude
• The work is said to be done efficiently or the machine is considered to be efficient
when the MA is greater than 1
• This implies that the efforts required to do the work are less than the magnitude of
resistance
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17.  When the MA is less than 1, the machine is said to be less efficient and shows a
mechanical disadvantage.
 This implies that the efforts required to do the work are greater than the magnitude
of resistance
 In Physiotherapy Levers and Pulleys can be used by applying the principle of
Mechanical Advantage
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18. The efficiency or effectiveness of a force in association with a lever depends on two
factors - the force applied (W) or (E), and its perpendicular distance from the fulcrum
(weight’s arm or effort’s arm)
If the weight’s arm and effort’s arm are of equal length, then an effort of an equal
magnitude as that of the weight is required to lift the weight
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19. Zero advantage is gained but the machine can be used for measuring weights
For eg – common balance
If the length of effort’s arm exceeds that of the weight’s arm, less effort is required to
achieve the similar result and an advantage is gained by the use of the lever ie
Mechanical Advantage
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20. LEVERS IN HUMAN BODY
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1ST ORDER
Eg - Nodding movement of head
Lever - Skull
Fulcrum - Atlanto-occipital joint
Weight - Anteriorly in the face
Effort - By contraction of posterior neck
muscles (applied at their attachment on the
occipital bone)

21. 2nd ORDER
• Mechanical Advantage is always present in Second order lever
• Eg - Heels raised to stand on toes
• Lever – Tarsal and Metatarsal bones
• Fulcrum – Metatarso-phalengeal joint
• Weight – The weight of the body is transmitted to the talus bone through the ankle joint
• Effort – At the insertion of tendo-calcaneum (Achilles tendon - applied by contraction
of calf muscles)
• Eg - The action of Brachioradialis muscle in flexing the elbow joint
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22. Heels raised to stand on
toes
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Calf Muscles

23. The action of Brachioradialis
muscle in flexing the elbow joint
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Brachioradialis
muscle

24. 3rd ORDER
• Mechanical Advantage is never present in Third order lever
• The feature of this lever is Velocity and the loss of mechanical advantage is
surpassed by the advantage gained by speed and range of movement
• Eg - Elbow flexion by Brachialis muscle
• Eg - Knee flexion by Hamstring muscle
• Eg - Knee extension by Quadriceps muscle
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25. Elbow flexion by Brachialis muscle
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• Lever – Forearm
• Fulcrum – Elbow joint
• Weight – Object held in the hand
• Effort – By contraction of the brachialis
muscle (applied at it’s insertion)

26. LEVERS 26
Knee flexion by Hamstring muscleKnee extension by Quadriceps muscle
Quadriceps muscle
Hamstring Muscles

27. • The human body achieves movement and adaptability by means of system of levers
• A knowledge of principles of lever is imperative for understanding method of
progression in muscle strengthening
• As the strength of the muscle increases the weight or resistance to be overcome
should also be increased.
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LEVERS IN PHYSIOTHERAPY

28. • In human body, in relation to the joints the insertions of muscles (E) are fixed. Thus
the only factors that can be changed are the weight and its perpendicular distance
from the fulcrum
• Thus added resistance can be administered either by increasing the weight to be
overcome or by increasing the length of the weight's arm (increasing the leverage)
• For eg – In prone lying while performing hip extension, resistance applied at knee
joint is more easily overcome by the extensors than the same resistance applied at the
foot when the knee is straight.
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29. • Clinical Implication –
• In deltoid paresis, it is easier for the patient to perform abduction of shoulder joint
with elbow flexed as compared to when the elbow is straight
• Abduction with flexed elbow reduces the leverage, thus relatively weak muscles can
perform the movement; whereas when the elbow is straight and the leverage is
increased a more powerful contraction is required.
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30. University Questions
1. Classification of Lever with examples . (7m, Summer 2014)
2. Describe Anatomical lever and explain its types with examples (5+10, Summer 2015)
3. Anatomical lever (7m, Summer 2017)
4. Classification of Lever with examples . (7m, Winter 2014)
5. Discuss levers in human body with respect to mechanical advantage (15m, Winter
2015)
6. Define a lever. Which are the different types of levers? Write in detail about all types of
levers in the human body with one example each (15m, Summer 2016)
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31. References
1) Gardiner DM. The Principles of Exercise Therapy. 4th ed. India: CBS; 2005
2) Hollis M, Fletcher-Cook P. Practical Exercise Therapy. 4th ed. Great Britain:
Blackwell Science;1999
3) Houglum PA, Bertoti DB. Brunnstrom’s Clinical Kinesiology. 6th ed. Philadelphia:
F.A. Davis Company; 2012
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32. Thank you
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