What is the purpose of a warm-up before physical activity?

The primary purpose of a warm-up before physical activity is to prepare the body for the demands of exercise. This involves gradually increasing the heart rate, enhancing blood flow to the muscles, and improving the efficiency of the cardiovascular and respiratory systems. A proper warm-up can also help to enhance muscle elasticity and joint flexibility, reducing the risk of injuries. By priming the body for physical activity, individuals are more likely to perform at their best and to execute movements with proper technique.

The other options, while not entirely unrelated to the effects of warming up, do not encapsulate the primary objective as effectively. Improving focus and concentration can be a benefit of warming up but is not its main purpose. Increasing body temperature occurs during a warm-up but is one of the physiological changes that contribute to preparation rather than the overarching goal itself. Minimizing water intake is not a goal of a warm-up; in fact, hydration should be maintained for optimal performance during exercise. Thus, the correct answer emphasizes the comprehensive preparation role a warm-up plays before engaging in physical activity.