What is tempo training?
Also known as an anaerobic threshold (AT) run or lactate-threshold run, the tempo run was popularized by Jack Daniels, Ph.D., about a decade ago. His definition:
"A tempo run is nothing more than 20 minutes of steady running at threshold pace."
(He goes on to say that 20 minutes is ideal, but may be varied to suit the needs of a particular course.) Without getting too technical, threshold pace is the effort level just below which the body’s ability to clear lactate, a by-product of carbohydrate metabolism, can no longer keep up with lactate production. Daniels states that this pace is, for most people, about 25 to 30 seconds per mile slower than current 5K race pace.
Why do it?
By performing steadily at your anaerobic threshold (AT), lactate and hydrogen ions—by-products of metabolism—are released into the muscles. The ions make the muscles acidic, eventually leading to fatigue. The more trained you become, the better your muscles become, at using these by-products. The result is less-acidic muscles (that is, muscles that haven't reached their new "threshold"), so they keep on contracting, letting you run farther and faster.
How do you know when you are at your AT?
One way is to establish HR Zones, based on your Max and resting HR. Another way is to do a blood lactate test. A more straightforward way to know, is the 'talk test'. If you maintaining a steady pace that is achievable, yet all of your breathing is necessary to maintain the effort i,e. you are breathing so hard you can't talk - you are right around your AT.
And just because the talk-test lacks a monitor, doesn't mean it is less effective. Testing has shown that experienced athletes can monitor their pace better than a HR monitor can. One reason for this, is that the AT fluctuates, so sticking to a number doesn't account for this, whereas if you listen to your body, you can tell when you are hovering right on AT.
One tell tale sign that you are reaching AT is a little gasp of breath, and if you hold back - a sense of 'settling in' to your pace. This is due to the lungs blowing off excess carbon dioxide, produced as a result of the increased oxygen demands as the body begins to produce lactic acid. At this point, it's important to remember that your task is to hover at AT, not to go as hard-as-you-can. And this brings up one of the core benefits of Tempo training -- you learn your body. You learn how you can gently push yourself, without 'blowing-up'. You learn how you can maintain a high-effort and for many people, this builds confidence and self-awareness - two critical components, in performing well.
Doing it well.
Remember, the one real requirement of tempo training is that you stick to a steady, specific, planned pace. Beyond that you have many options. For most folks, running on a flat course is a good way to start, but races have hills - so practice maintaining a given intensity regardless of the terrain and you'll benefit from learning up to go up and down the gears, so to speak, and to maintain that steady flow, no matter whether you are going up down or on the flat.
As part of a training program including long endurance training, interval and recovery/easy runs, a once-per-week tempo run, is a strategy that is sure to boost your running, cycling or climbing. For many folks, it's the highest quality workout of the week and it's good to go into it rested, fueled and ready for a positive effort.