As many as possible. The rules are against intentionally knocking them down; if they are unintentional, it doesn't matter. The American record that Allen Johnson set was done while he hit every single hurdle
In high school, the 400m hurdles race becomes the 300m hurdles, although some high school hurdlers also compete at the 400m level. Here are the distances for both: 300m hurdles: To first hurdle:45m; 147' 9" In between hurdles: 35m; 114' 9" Last hurdle to finish line:10m; 32' 10" 400m hurdles: To first hurdle:45m; 147' 9" In between hurdles: 35m; 114' 9" Last hurdle to finish line:40m; 131' 3"
There are ten hurdles in 100m, 110m and 400m hurdles races.
Ten. The first hurdle is 45 meters from the start. The following nine hurdles are evenly spaced, 35 meters apart, and there is 40 meters from the last hurdle to the finish line.
The distance between 300 Hurdles (or 400 Hurdles) is 35 meters. The distance to the first hurdle (in high school races) is 45 meters and 10 meters from the last (8th) hurdle to the finish line. This is exactly the same as the first 300 meters of a 400 Hurdle race, though the relative position on the track is moved to finish at the common finish line. All the distances on hurdle spacing are available at: http://www.trackinfo.org/hurdles101.html
Strictly speaking there are no hurdles in a 400m race, but in a 400mH race there are ten hurdles per lane.
The 300m hurdles race is run in high school track and field (once in college the race is 400m hurdles). For the girls' race, the hurdles are 30 inches high - for the boys' race, the hurdles are 36 inches.
The 200m hurdle distances are: 20 meters to the first 35 meters between each hurdle 40 meters from the last hurdle to the finish line So just start at the normal 200m start line and run the second half of a 400m hurdles race. This race is generally only contested in Youth and Masters competitions with a few exceptions. The old Olympic 200 hurdles was the 220 yard low-hurdles: 20 yd to the first hurdle 20 yd between hurdles 20 yd from the last hurdle to the finish This race was contested over low hurdles (30") and was dropped from the the Olympic roster after the 1904 Olympics.
Strictly speaking there are no hurdles in a 400m race, but in a 400mH race there are ten hurdles per lane.
Runners jump obstacles in the following races: Women's 100m hurdles Men's 110m hurdles 400m hurdles 3000m steeplechase
No, college has 400m hurdles instead
Both men's and woman's 300m hurdles races have 8 hurdles in them. However, the 300m hurdle race is not run professionally or in collegiate competition. Instead, the 400m hurdles is run, with 10 hurdles.
There is no "low hurdles" event. Men's intermediate 400m hurdles is 36 inches. Women's intermediate 400m hurdles is 30 inches. Women's high hurdles is 36 inches