Biomech: Lever Systems

Question 1

Which of these depicts a first class lever system:
E-F-L or L-F-E

Answer 1

Both are correct. The fulcrum is always in the middle for a 1st class lever system.

Question 2

What is the one of the only second class lever systems we need to familiarise ourselves with?

Answer 2

Plantar flexion during a take-off

Question 3

How would you depict a second class lever system?

Answer 3

E-L-F or F-L-E.

The load is always in the middle.

Question 4

A bicep curl is an example of what type of lever?

Answer 4

Third class lever system. Fulcrum is the elbow, effort created by bicep attached to radius, load is in the hand.
F-E-L

Question 5

Can one joint have more than one lever system operating?

Answer 5

Yes e.g. flexion at elbow = third class whereas extension = first class

Question 6

The distance from the fulcrum to the effort is know as the….

Answer 6

Effort arm

Question 7

The distance from the load to the fulcrum is known as….

Answer 7

The load arm

Question 8

Which lever system has the greatest mechanical advantage?

Answer 8

Second class lever system where effort arm (distance from fulcrum to effort)is greater than the load arm (distance from load to fulcrum)

Question 9

Why is a third class lever system considered to have a mechanical disadvantage?

Answer 9

Load arm is larger than the effort arm resulting in a large effort being required to move a relatively small load.