What type of lever occurs when the muscle force and resistance force are applied on opposite sides of the fulcrum?

The first class lever is characterized by the arrangement where the fulcrum is positioned between the muscle force (effort) and the resistance force (load). In this system, both forces are applied on opposite sides of the fulcrum, which allows the lever to pivot efficiently. An example of a first class lever in the human body would be the action of the neck when the head is tilted backward; the fulcrum is at the atlanto-occipital joint, the muscle force is supplied by the neck extensors, and the resistance is the weight of the head.

This type of lever is particularly effective for balancing loads and can either amplify force or speed depending on the placement of the fulcrum relative to the effort and load. Understanding the mechanics of first class levers is essential for fitness instructors, as it aids in comprehending how various movements are executed and how to optimize exercise techniques for strength and efficiency.