Stride length is reduced , so to achieve competitive speeds , racewalkers must attain cadence rates comparable to those achieved by Olympic 800-meter runners-and they must do so for hours at a time since the Olympic events are the 20 km ( 12.4 mi ) race walk ( men and women ) and 50 km ( 31 mi ) race walk ( men only ) , and 50 mile ( 80.5 km ) events are also held .
Stride length is reduced , so to achieve competitive speeds , race walkers must attain pace rates comparable to those achieved by Olympic 400-meter runners ; and they must do so for hours at a time since the Olympic events are the 20 km race walk and 50 km race walk .