You hear it all the time when you're training for a race: Go do a tempo run. What exactly is a tempo run though?
Basically, a tempo run is when you run for 20 minutes at your lactate threshold. For most people, this pace is equal to about 25-30 seconds slower than your 100% 5K pace. If you know your heart rate maximum (HRM) number, your heart rate during a tempo run is 90% of your HRM. Or, if you just want a simple two-word explanation, a tempo run should feel "comfortably hard" and can be held for about an hour during a race.
Tempo running is most useful when running at least a 15K because your success largely relies on your body's endurance, rather than an all out sprint. What is most important when doing a tempo run is that you 1) KEEP CONSISTENT PACE and 2) KEEP A SPECIFIC PACE. That being said, tempo runs can be varied based on your course, the type of race you are doing, and your own personal running style. So as long as you set out with a specific plan, have fun with the workout.
If you are still confused on pacing, here's a tip: pick your favorite upbeat song and pace your run by keeping beat with the song.
So go make a playlist that includes 20 minutes worth of fast tempo songs, remember to do at least a 5-10 minute warm-up and cool-down jog, and start working tempo runs into your running program today!