Which of the following best describes an isotonic exercise?

An isotonic exercise is characterized by muscle movement that occurs with contraction against a consistent resistance, which leads to a change in muscle length. This type of exercise typically involves both the concentric phase, where the muscle shortens as it contracts, and the eccentric phase, where the muscle lengthens while maintaining tension. Common examples include weightlifting, where the load moved represents a fixed resistance, and exercises like push-ups or squats, where body weight is used as resistance.

The focus on muscle movement and contraction in isotonic exercises is fundamental for building strength and endurance, as it enables the muscles to work through the range of motion continuously. Other forms of exercise, such as isometric exercises, involve holding a position with no change in muscle length, while controlled breathing is more associated with techniques used during various workouts rather than defining an exercise type. Skill-based movements pertain to agility and coordination rather than emphasizing muscle contraction and movement, which is the core of isotonic exercises.