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We’ve all heard of tempo runs, and have probably done many of them over our lives. But what exactly is a tempo run? 

If you poll a dozen runners, you’re likely to get a dozen different answers. To some, it’s —wildly different for milers and marathoners. To others it’s any long, fast run at a steady pace.

The Origins of the Tempo Run

Scientifically, the concept stems from in the European Journal of Applied Physiology and Occupational Physiology by a team led by Bertil Sjödin of Sweden’s National Defense Research Institute. 

In that study, Sjödin and colleagues put eight experienced distance and middle-distance runners on treadmills and measured their blood chemistry at various paces, with a particular eye to their lactate levels. They then asked their study subjects to do weekly 20-minute training runs at a pace they called vOBLA—the speed at which the treadmill tests had shown them to be experiencing an “onset of blood lactate accumulation.”

The results were astounding. 

After 14 weeks of once-a-week runs of this type, the runners saw their average vOBLA paces drop from 5:43 per mile to 5:29—a whopping 4% improvement, roughly equivalent to seeing their 10-mile race times drop from 57:10 to 54:50.

More recently, of 22 nationally and internationally competitive Spanish runners (average 10K time 31:35) by Jordan Santos-Concejero and colleagues from the University of the Basque Country in northern Spain found that each 10 seconds per mile difference in vOBLA corresponded to a 70-second difference in 10K PR. 

Neither of these studies actually uses the term “tempo run,” but the theory behind such runs is built on these two key findings: (1) doing tempo runs at or around vOBLA can markedly boost your vOBLA; (2) high vOBLA (colloquially referred to as “lactate threshold” or “aerobic threshold”) corresponds to better racing performance.

How to Calculate Your Tempo

Actually doing an effective tempo run is, of course, not quite that simple. To start with, most of us aren’t blessed with cheap, easy access to an exercise physiology lab that can tell you precisely what your tempo pace is. (Not to mention that exercise physiologist Owen Anderson, in his book , points out that blood lactate levels, and therefore vOBLA, can vary daily, based on everything from how much sleep you’re getting to when you ate lunch.) 

But you don’t need to know your vOBLA all that precisely in order to do tempo runs, and there are some good ways to approximate it without resorting to an exercise physiology lab. 

The simplest is by extrapolating from race pace. According to Jack Daniels, author of , your tempo pace (which he calls threshold pace) is the pace at which you can run a race lasting about an hour. That’s why elite men often do tempo runs at half-marathon pace, since for them, 60 minutes is pretty close to half-marathon time. For mortals, it might be closer to 15K, 12K, or even 10K pace.

A related method, created decades ago by Daniels and his then-associate, Jimmy Gilbert, involves plugging your race times into what they called VDOT tables (). These allow you to convert your current running ability at any distance into something akin to VO2max—which they called VDOT. Once you’ve determined your VDOT, these tables then allow you to convert it into training paces, including an estimate of your threshold (tempo) pace.

Another surprisingly good estimate can be made by doing a 30-minute time trial. This test comes from cycling and triathlon coach Joe Friel, who debuted it in a 2000 article in Inside Triathlon.

It requires a heart rate monitor, and must, Friel insists, be done solo, because doing it in a race or with training partners will induce you to run harder than you can alone, changing the outcome. 

If you use this test, ignore your heart rate in the first ten minutes, when you’re still warming up. What you want is its average during the final 20 minutes. That’s the heart rate, Friel says, that you want to duplicate in tempo workouts.

Some other tests have been suggested and used over the years, but generally found to report a threshold pace up to 10% faster than that revealed by these tests. 

Part of the confusion over what exactly is the perfect tempo pace stems from the physiology of the lactate “threshold.” 

As their terminology indicated, Sjödin and colleagues thought of VOBLA in terms of an “onset” of blood lactate accumulation. But the reality is that blood lactate levels don’t suddenly shoot up when you hit this threshold. Instead, when you plot lactate vs. pace, you get a curve that looks more like a hockey stick than a shelf bracket. I.e., there’s clearly a kink in it, but it’s a rounded-out kink, and the exact moment of lactate “onset” is hard to define precisely.

Variations of Tempos

All of this means that there are a number of ways to run tempo-style runs. Here are a few alternatives:

Classic 20-minute tempo run. This is what Sjödin’s team used in their experiment and it’s still a great workout: 20 minutes at your best estimate of VOBLA. (You can also do this as a 3-mile run, so long as your tempo pace doesn’t make that too different from 20 minutes.) 

If you’re doing this, I’d suggest doing it the first time at your best estimate of your tempo pace from the VDOT tables (or Friel’s time trial test, if you prefer to work via heart rate). If that seems too easy, you can let it drift slightly faster—but remember that tempo pace is generally “fun-fast,” and not so taxing it feels like a time trial.

Tempo repeats. These are multiple shorter tempo runs done at the same pace you’d use for the classic 20-minute tempo run. For example, you could run 2 x 10 minutes (or 2 x 1.5 miles, if you prefer to think in miles). High-volume runners, especially those training for a marathon, can extend the total to well more than 20 minutes, if they wish (although some phase-in may be required). 

My formula for these is not to go any longer than 20 minutes in any given repeat, and to limit total distance to either 3 miles or 10% of weekly volume, whichever is larger. That means that a 90-mile per week runner can, in theory, even do 3 x 3 miles—but unless they’re in peak training for a marathon, they’ll probably find that excessive. Most people are content to limit the total to 3 or 4 miles. 

Recovery between repeats should be an easy jog for about 60-90 seconds per mile of the preceding tempo repeat. E.g., if you run 2 x 2 miles, your recovery would be 2-3 minutes.

Cruise intervals. These are similar to tempo repeats but shorter, and done on proportionally shorter recoveries (short enough that on a track, you’ll probably just jog in a slow circle, returning to the point where you quit the previous repeat in time to start the next). 

Distances can be as low as 600 meters or as high as a mile. Recovery times are 20-30 seconds for 600 meters, 60-90 seconds for a mile, and somewhere between for intermediate distances. 

Volumes can go one mile higher than for tempo repeats (e.g., I use 11 x 600 as a substitute for a 3-mile tempo run), and paces can be a bit above your VDOT/Friel tempo pace, especially at 600 meters—but only by 1-2 seconds per lap. This might be a good opportunity, for example, to test how your body responds to the pace recommended by the Conconi or 3,200-meter-time-trial tests. 

This is a fun, quick workout, best run with a pace-matched training partner so you can start each repeat together. The first half of it should feel pretty easy. The “magic” is in the later parts, when those short recoveries start to feel…well, short. 

Alternations. In the 1970s and ‘80s, Australian superstar Robert de Castella, who set the marathon world record at 2:08:18 in 1981, perfected a workout in which, instead of running a standard tempo run, he alternated pace between faster than threshold and slower than threshold. What he was doing, exercise physiologists know today, was training the body’s in which it shunts excess lactate from hard-working leg muscles to tissues that can make better use of it in a process that may be particularly effective at increasing vOBLA. De Castella’s original version alternated between quarters at 5K pace and 200s about a minute per mile slower, and extended for 3 miles. But it’s possible to do many other variants, such as alternating between 600s at 10K pace and 400s at marathon pace, or to run sets much shorter than 3 miles, separated by recovery jogs.

Predator runs. This “progression run” variation is a concept I got from Scott Simmons, then coach of the American Distance Project, and Cory Ihmels, head coach at Boise State University. The idea is to start at warm-up pace, then speed up slowly and steadily like a predator drawing ever closer to its prey. These can be longer than the classic 20-minute tempo (perhaps 6 to 10 miles, depending on your weekly volume), because you are starting slowly, then increasing pace, mile-by-mile. In the process, you will, at some point, move through vOBLA, which makes it an ideal run if you’re not quite sure what your true threshold pace might be. Just be careful not to turn the final mile into a race.