Tempo runs should be run at about the effort you could hold for a one-hour race, or "comfortably hard." For most runners, it's somewhere between their 10K and half marathon race paces.
When in doubt, run slower than you think you should. Tempo runs become counterproductive when they're done too fast, so focus on running at a hard but manageable pace.
Sometimes a workout can go wrong but it can always be salvaged and turned into a productive session. Here's how to address the most common tempo run problems.
"I went out too fast!"
The problem with going out too fast is you've spiked your heart rate and lactate production, so if you continue at this pace, your tempo run will turn into a VO2 max repetition. It's also risky to run too fast because you're more likely to get a running injury.
If you realize you're running too fast, slow down for a minute to about 10 to 20 seconds slower than your tempo pace. This will allow your heart rate to decrease, and you can then gradually get back to your appropriate effort level.
"It's too hot/cold/windy!"
The weather has a serious effect on any tempo workout by making it seem harder than it should. The fix is simple: Adjust your expectations and slow down. Focus on the effort of the workout, not the pace. Now is a good time to leave your GPS watch at home.
If you're running in the summer, it's best to run first thing in the morning when the sun is at its weakest and the temperature is still manageable in the early hours. Can't run in the morning? Wait as long as you can later in the day and find shade if possible. And of course, start your run well hydrated.
"I get too out of breath and have to stop during my tempo runs."
If you have to stop and catch your breath during a tempo workout, you're running them too fast. Your heart rate should be approximately 85 to 90 percent of its maximum, which should feel difficult but manageable. Any faster and you'll need more recovery, which is not the point of a good tempo run.
Once you learn to run by feel and focus on effort, then account for the weather, you'll have many more successful tempo workouts. And you'll become a much faster runner.race.