The term “tempo run” was first popularized by Jack Daniels and the formal definition of a tempo run is a run at lactate threshold pace. This is the fastest pace that a runner can maintain for one hour. Every runner has his or her unique tempo pace depending on ability and current fitness level.

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Sustained effort training runs, usually 20 to 30 minutes in length, at 10 to 15 seconds per mile slower than 10-K race pace. Another way to gauge the pace of tempo runs: a pace about midway between short-interval training speed and your easy running pace.

See more definitions in the Definitive Guide to Running Terms.