Which of the following is a proactive measure to reduce risks of injuries in physical education?

Engaging in a warm-up is a proactive measure for reducing the risk of injuries in physical education because it prepares the body for physical activity by increasing blood flow to the muscles, enhancing flexibility, and improving overall coordination. Adequate warming up raises the body temperature and can help prevent strains and sprains by gradually increasing the intensity of workout activities. A well-structured warm-up can also mentally prepare students for physical activity, thus promoting focus and readiness.

In contrast, locating the exit doors is a safety concern but does not directly contribute to injury prevention during activities. While knowing exits is important for emergency preparedness, it does not help to physically ready the body for exercise. Contacting the principal during an emergency addresses a crisis situation rather than proactively preventing injuries. Assigning students to set up and break down equipment ensures that procedures are followed but does not address the physical readiness of participants, which is crucial for injury prevention. Thus, while all options have their merits within a physical education context, engaging in a warm-up directly reduces the risk of injuries through physical preparation.