If you are trying to learn how to run faster, you should mix your tempo runs with interval training, which is an even more effective speed builder.
Note, however, that overdoing interval training can lead to injury. Thus, tempo runs are an excellent addition to help build your long distance speed.
Also, a tempo run once per week provides some additional benefits that interval training cannot provide.
A tempo run is a 10- to 60-minute run at your intended race pace, meant to build your speed and train your body to maintain race pace.
The distance of a tempo run varies based on the length of the race you're training for. If you're training for a marathon, a 60-minute tempo run, after a warmup of one mile, might be a great goal. If your race is a 5K, then obviously a 60-minute run at race pace is out of the question. You'll be running 2 to 3 times the distance of the race!
Tempo runs to train for a 5K should be 10- to 15-minutes, depending on how fast you run a 5K. Half your 5K distance (2.5 kilometers or 1.5 miles) should be plenty.
Tempo runs have several benefits:
A tempo run once per week teaches you to know your race pace so that you can maintain it.