The goal of tempo running is to increase your endurance by improving your body's ability to clear lactate—more commonly known as lactic acid—from your muscles. The technical term for a tempo is really a lactate threshold run, where you run right on the threshold of aerobic and anaerobic running.
So what exactly does that mean? It's simple: As you run faster, your body produces more and more lactate, which contributes to fatigue and that uncomfortable burning sensation at the end of a hard workout or race.
For every runner, there's a point where you're running hard enough that you can't clear lactate as fast as you're producing it. Then you're working anaerobically (meaning, "without oxygen") and you only have a few minutes until you need to slow down or stop.
A tempo run is done right on the threshold of aerobic vs. anaerobic running. Prolonged periods of running with high—but not too high—lactate improve your body's ability to clear it from your bloodstream, allowing you to boost your endurance. For anyone with big marathon goals, this is the perfect workout.
Find Your Tempo Pace
Because tempo runs are based on a physiological phenomenon and not a specific pace, the exact pace you should strive for is subjective and affected by several factors including:
- Heat and humidity
- Terrain and elevation
- Fatigue and soreness from previous workouts
Since your exact tempo pace can vary based on these factors, it's best to run by feel or perceived effort.