Tempo Runs are steady runs at lactate threshold pace that last 20 minutes or more. You should be able to maintain this pace for up to an hour in a race. In order to maintain a steady rhythm, it is recommended that tempo runs are done in mild weather conditions on flat even terrain; the goal is to maintain an even intensity of effort for a long period of time. Hills, uneven footing and poor weather conditions all interfere. A tempo run should be sandwiched between a good warm up and a cool down. Because they involve running at lactate threshold pace for a longer, concentrated period of time, tempo runs are a better use of training time than lactate threshold runs.
Lactate Threshold or “Cruise” Intervals are repeated runs at lactate threshold pace that last anywhere from 3 – 15 minutes and are broken up by short recovery periods. The brief recovery periods, which usually last about a minute, allow blood lactate levels to remain fairly constant and extend the training session a bit longer than a tempo run. Lactate threshold intervals can be anywhere from 800 meters to 2 miles in length and should also be sandwiched between a warm-up and cool down. The advantage of lactate threshold intervals is that they provide a break from the demands of the longer tempo run while still allowing an opportunity to benefit from a full lactate threshold session. They are easier to do. Like tempo runs, these should be done on a flat, even surface in mild weather conditions.