Every four years the winners of the Olympic gold medals in the 100 meter runs are unofficially crowned as the world’s fastest man and woman. How fast can they run? How fast can the winners of longer races and average runners run?

## How to Calculate Average Speed

To calculate the average speed of anything physicists divide the total distance by the time it takes to travel that distance. The formula is:

average speed = distance/time.

People often use the words speed and velocity interchangeably, but in physics they have different meanings. Velocity includes direction; speed does not.

To find the average speed someone runs in a race, divide the length of the race by the time required to complete the race. The appropriate speed unit will be the distance unit per the time unit. If the distance is in meters and the time is in second, the speed is in meters per second, which can be converted to miles per hour.

### World’s Fastest Man or Woman

According to the Olympics website, both the world and Olympic record in the 100 meter dash was set for men by Usain Bolt in the 2008 Beijing Olympics with a time of 9.69 seconds. Dividing the distance by the time gives an average speed of 10.3 meters/second. Multiplying this speed by 3,600 seconds in an hour and dividing by 1,609 meters in a mile gives his average speed as 23.1 miles/hour.

Florence Griffith Joyner set the women’s 100 meter Olympic record in the 1988 Seoul Olympics at 10.62 seconds, however she set the world record two months earlier in Indianapolis at 10.49 seconds. She ran her world record at an average speed of 9.53 meters/second or 21.3 miles/hour.

These speeds are impressive, but not sustainable. What speeds can people sustain over long distances?

### World’s Fastest Marathons

Haile Gebrselassie set the men’s marathon world record at the 2008 Berlin marathon. He ran the 26.2 mile distance in 2 hours 3 minutes 59 seconds. His average running speed for this distance was 5.67 meters/second or 12.7 miles/hour.

Paula Radcliffe set the women’s world marathon record at the 2003 London marathon, when she ran the marathon in 2 hour 15 minutes 25 seconds. She ran the 26.2 miles at an average speed of 5.19 meters/second or 11.6 miles/hour.

### Western States 100 Mile Endurance Run

To get an idea of human speeds sustainable for even longer distances, look at the results of the Western States 100. This endurance race is a 100.2 mile run in the Sierra mountains of California. Runners battle cold, heat, mountains, and distance to complete this race, click here.

Scott Jurec set the men’s record in 2004 by running the 100.2 miles in 15 hours 36 minutes 27 seconds. Ann Trason set the women’s record with a time of 17 hours 37 minutes 51 seconds in 1994. Jurek’s average speed was 6.4 miles/hour and Trason’s was 5.7 miles/hour. Ordinary humans can attain these speeds but few can sustain them for 100 miles.

### Speeds for Average Humans

The above speed records are impressive and of course represent the fastest people on Earth. How fast is the average person? More typical marathon times of 3, 4, 5, or 6 hours require average speeds of 8.7, 6.6, 5.2, or 4.4 miles/hour. The Western States 100 has a 30 hour time limit which requires running at an average speed of 3.3 miles/hour for 100 miles.

With proper training people can run at impressive speeds for sustained distances.

### Addendum

**New World Record**

After this article was published, the author learned that Bolt broke his own record. On August 16, 2009, running in the Berlin stadium made famous by Jesse Owens in 1936, Bolt ran the 100 meter distance in 9.58 seconds. His average speed was 10.44 meters/second or 23.36 miles/hour.

**Another New World Record**

On August 20, 2009, Bolt followed up with a world record at 200 meters at 19.19 seconds. His average speed of 10.42 meters/second = 23.32 miles/hour was only a little slower than for his 100 meter record.