Biomechanics Lecture: Understanding Levers

Introduction

• Presenter: Mr. D
• Series: Biomechanics for Beginners
• Topic: Levers in biomechanics — part of a series on biomechanics.
• Focus: First, Second, and Third class levers and their relation to the human body, sport, and performance.

Basics of Levers

• Definition: A lever is a system consisting of a bar and a fulcrum.
• Biomechanical Interpretation:
  • Bars: Bones
  • Fulcrum: Joints
  • Force: Muscle contractions

Types of Levers

First Class Levers

• Structure:
  • Fulcrum (axis) is in the center.
  • Force (effort) is applied on one side.
  • Resistance (load) is on the opposite side.
• Body Example:
  • Skull as resistance.
  • Fulcrum is where the skull meets the spine.
  • Muscles contracting cause the head to tilt backwards.
• Real-Life Analogy: Seesaw
  • Force applied down causes load to go up.

Second Class Levers

• Structure:
  • Fulcrum is on one side.
  • Resistance is in the middle.
  • Force is on the opposite side.
• Body Example:
  • Fulcrum at toes.
  • Resistance is the weight of the body.
  • Force is the calf muscles contracting.
• Real-Life Analogy: Wheelbarrow
  • Wheel as pivot point.
  • Force applied by pushing up.
  • Resistance is the load in the wheelbarrow.

Third Class Levers

• Structure:
  • Fulcrum is on one side.
  • Force is applied close to the fulcrum.
  • Resistance is on the opposite side.
• Body Example:
  • Fulcrum is at the elbow joint.
  • Resistance is the weight of the arm.
  • Force is the contraction of the bicep.
• Real-Life Analogy: Fishing
  • Fulcrum is where hands meet the fishing rod.
  • Resistance is the fish pulling down.
  • Force is the contraction of the biceps.

Conclusion

• Reviewed the three types of levers in the body.
• Encouragement to engage by liking the video, asking questions, and subscribing to the final part of the series on equilibrium.