Race walking is an Olympic track and field event that originated in the late 19th century in England. It differs from running in that one foot must always be in contact with the ground. There are two main rules: the back foot cannot leave the ground until the front foot makes contact, and the supporting leg must remain straight. Events are held at distances from 3km to 50km, with modern Olympics featuring men's and women's 20km and men's 50km. Proper technique involves keeping proper posture, bending the elbows at 90 degrees during arm swings, and ensuring one foot remains on the ground at all times through pelvic rotation and straight legged strides. Athletes are disqualified if two judges agree they have