Kinesiology – Angular Kinetics 1. Joints as Lever Systems: There are three types
ID: 1795862 • Letter: K
Question
Kinesiology – Angular Kinetics
1. Joints as Lever Systems: There are three types of lever systems, 1stclass, 2ndclass, and 3rdclass. Understanding the differences between the three classes will help you better understand how the body functions and how to perform exercises in a safe and effective manner.
A. Define 1stclass lever and provide 2 examples of a 1stclass lever system. Oneexample must be an example unrelated to the human body (i.e. an example you see out in the world) and the second must be an example within the human body occurring at a particular joint.
B. Define 2ndclass lever and provide 2 examples of a 2ndclass lever system. Oneexample must be an example unrelated to the human body (i.e. an example you see out in the world) and the second must be an example within the human body occurring at a particular joint.
C. Define 3rdclass lever and provide 2 examples of a 3rdclass lever system. One example must be an example unrelated to the human body (i.e. an example you see out in the world) and the second must be an example within the human body occurring at a particular joint.
Explanation / Answer
Levers are used to carry weight more than the capacity of the individual
There are 3 types of lever
class 1 lever has the fulcrum between the input force and load
Example of human body - joint between the head and the first vertebra (the atlantooccipital joint) The weight (resistance) is the head, the axis is the joint, and the muscular action (force) come from any of the posterior muscles attaching to the skull
Outside example - See Saw, Scissors
Class 2 lever has the load between the fulcrum and the input force.
Example in the human body of a second-class lever is found in the lower leg when someone stands on tiptoes.
Outside example - Wheel barrow
Class 3 lever force is applied between the resistance (weight) and the axis (fulcrum)
Example in the human body - elbow joint . The joint is the axis (fulcrum). The resistance (weight) is the forearm, wrist, and hand. The force is the biceps muscle when the elbow is flexed.
Other example - using a shovel to pick up an object. The axis is the end of the handle where the person grips with one hand. The other hand, placed somewhere along the shaft of the handle, applies force. At the other end of the shovel (the bed), a resistance (weight) is present.
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