What distinguishes isotonic exercises from isometric exercises?

The distinction between isotonic and isometric exercises lies primarily in the type of movement involved. Isotonic exercises are characterized by the contraction of muscles with movement, meaning that the muscles shorten and lengthen during the activity. This dynamic movement can be observed in activities such as lifting weights, performing squats, or doing push-ups, where a joint angle changes as the muscle contracts.

In contrast, isometric exercises entail muscle contraction without any significant change in the muscle length or joint angle. For example, holding a plank position or pushing against a wall involves applying force without movement. Thus, isotonic exercises are primarily focused on the movement aspect, which is why identifying isotonic exercises as those involving movement is the correct choice.

The other options do not accurately capture the primary distinguishing factor between these two types of exercises. Breathing control can be a part of any exercise, regardless of whether it is isotonic or isometric. The use of equipment is not exclusive to isometric exercises, as both types can utilize equipment or be performed without it. Weight lifting is a form of resistance training that can include isotonic movements but does not define isometric exercises, which can also be performed without weights.