NETA Personal Trainer Practice Exam

What type of lever is characterized by the muscle force and resistance force acting on opposite sides of the fulcrum?

1. First class lever

2. Second class lever

3. Third class lever

4. Quaternary lever

The correct answer is: First class lever

A first class lever is characterized by the muscle force and resistance force acting on opposite sides of the fulcrum. In this type of lever, the fulcrum is located between the effort (the muscle force) and the load (the resistance force). This arrangement allows for a balance of forces, providing efficiency in movement. A common example is the action of a seesaw, where one end raises while the other end descends, demonstrating the opposing forces working around a pivot point. In a second class lever, the resistance is positioned between the fulcrum and the effort, which provides a mechanical advantage but does not fit the description provided in the question. Similarly, in a third class lever, the effort is applied between the fulcrum and the load, typically resulting in a greater range of motion at the expense of force. The term "quaternary lever" is not standard in biomechanics and does not apply here. To summarize, the defining feature of first class levers makes it the correct choice in the context of the question, as it emphasizes the opposition of muscle and resistance forces around the fulcrum.