Just like with the men's races, until 1935 no more than three hurdles could be knocked over (or the runner was disqualified) and records were only officially registered if the runner had cleared all her hurdles clean. In 1935, this rule was abandoned, and L-shaped hurdles were introduced that fell over forward easily and greatly reduced the risk of injury to the runner. Hurdles are weighted, so when properly set for the height (for women, closer to the fulcrum of the "L"), they serve as a consistent disadvantage to making contact with the barrier.