I'll try to answer this in an understandable way. . Tempo pace (also called "lactate threshold" pace) is a fast (race level fast) pace you can hold for about an hour. So a 10K or 10-mile race pace is frequently used (1/2 marathon pace for faster runners). The pace can be figured from other length races (5K or 10K for instance). The McMillan Running Calculator can figure paces for these workouts based on a recent race time. I find the paces tend to be a little fast.
http://www.mcmillanrunning.com/
Make sure you fill in all the fields correctly or the results will leave you scratching your head. Current race distance and time and target race distance and time. Guess on the target race time if you're not sure what your goal is.
