Heel-strike running is often considered inefficient and potentially harmful because the heel contacts the ground first with the leg extended in front of the body, creating a braking force that sends higher impact shock up through the ankle, knee, and hip joints. This impact loading can increase the risk of common overuse injuries such as shin splints, knee pain, and stress fractures, especially when combined with poor footwear or high mileage. Heel striking also tends to reduce running efficiency by wasting energy on deceleration rather than forward propulsion, making it harder to maintain speed and increasing fatigue over.