Which type of lever occurs when muscle force and resistance force are applied on the same side?

The correct answer is that a second class lever occurs when muscle force and resistance force are applied on the same side. In biomechanics, this type of lever system features the resistance located between the force (effort) applied by the muscle and the pivot point (fulcrum).

One common example of a second class lever in the human body is the calf raise. In this scenario, when the calf muscles contract, they apply force to lift the body upward against gravity (resistance). The fulcrum is at the ball of the foot, which allows the muscles to generate an effective movement because the applied force moment is greater than that of the resistance. This positions the resistance for the lever arm created by the line of action of the muscle force, leading to a mechanical advantage.

Understanding this classification of levers is crucial for fitness instructors when analyzing movements and designing exercise programs that optimize strength and efficiency. Second class levers usually require less effort by increasing the load moved while maintaining effective function in physical activities.