ACSM Personal Trainer Certification Practice Exam

What is the primary function of a 2nd Class Lever in the human body?

1. Primarily for range of motion

2. Primarily for speed

3. Primarily for power

4. Primarily for flexibility

The correct answer is: Primarily for power

The primary function of a 2nd Class Lever in the human body is to generate power. In a 2nd class lever system, the load is positioned between the effort (force applied) and the fulcrum (pivot point). This arrangement allows for a mechanical advantage, enabling a smaller effort to move or support a larger load. For example, when standing on tiptoes, the ball of the foot serves as the fulcrum, the body weight acts as the load, and the effort applied by the calf muscles allows you to lift your body. This design makes it advantageous for actions that require strength and support, as it can lift significant weight with less force. The other options describe functions that are better associated with other types of lever systems. For instance, range of motion is primarily facilitated by 1st class levers, while speed is more characteristic of 3rd class levers where the effort is between the load and fulcrum, allowing for faster movement over a greater distance. Flexibility is not a primary mechanical function of levers but instead relates more to the ability of muscles and joints to move through a range of motion.