4 stepping is less common, but it is when a hurdler switches their lead leg each hurdle.
Before 1987, the 60 yards hurdles – held over 60 yards (54.864 m) – was contested at the USA Indoor Track and Field Championships and other high-level American competitions.
Because the distances are so similar, a conversion of 0.01 seconds is sometimes applied in statistical lists to convert 60 yd hurdle marks to equivalent 55 m hurdles times.
[1] The 70 yards hurdles was also an uncommon distance held indoors beginning at the 1956 USA Indoor Track and Field Championships and ending by the 1963 Championships.
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