âThereâs called free circulating DNA, the fetus, some of its DNA gets into the maternal blood and we can actually detect that DNA -- the accuracy of these tests are about 99 percent,â Dr. Abdullah said, âWe can do this test around 10 weeks, so itâs very early in the pregnancy.â.
Daytona International Speedway is 2.5 miles (4 km) long and a 500-mile race requires 200 laps to complete. However, the race is considered official after half its distance (100 laps or 250 miles (400 km)) has been completed.
Fitness Level. The most important factor determining run speed over a long distance is the runnerâs fitness level. An elite athlete may complete a mile in less than five minutes, and the world record at the time of publication is three minutes and 43 seconds, held by Hicham El Guerrouj. Someone new to running, using a run-walk system to build her endurance, may need between 12 and 15 minutes.