Which of the following best describes a warm-up?

A warm-up refers to a gradual increase in physical activity designed to prepare the body for more vigorous exercise. This process is essential because it raises the heart rate, increases blood flow to the muscles, and enhances muscle elasticity, reducing the risk of injury. During a warm-up, activities typically begin at a low intensity and progressively increase, allowing the body to adjust safely to the demands of the upcoming workout or competition. This methodical approach helps to improve performance and prevents strains or sprains that may occur if the body is subjected to sudden high-intensity activity without preparation.

The other options do not accurately capture the purpose and structure of a warm-up. A sudden increase in workout intensity might lead to injury, while a rapid decrease in activity is related to cooldown routines. Unstructured physical activity lacks the focused and progressive nature required for an effective warm-up.