Roberts—who'd dabbled in faster-paced short efforts—learned to do a proper tempo run only when she began working with a coach, Toby Tanser. In 1995, when Tanser was an elite young track runner from Sweden, he trained with the Kenyan's "A" team for seven months. They ran classic tempos—a slow 15-minute warmup, followed by at least 20 minutes at a challenging but manageable pace, then a 15-minute cooldown—as often as twice a week. "The foundation of Kenyan running is based almost exclusively on tempo training," says Tanser. "It changed my view on training."
Today, Tanser and many running experts believe that tempo runs are the single most important workout you can do to improve your speed for any race distance. "There's no beating the long run for pure endurance," says Tanser. "But tempo running is crucial to racing success because it trains your body to sustain speed over distance." So crucial, in fact, that it trumps track sessions in the longer distances. "Tempo training is more important than speedwork for the half and full marathon," says Loveland, Colorado, coach Gale Bernhardt, author of Training Plans for Multisport Athletes. "Everyone who does tempo runs diligently improves." You also have to be diligent, as Roberts discovered, about doing them correctly.
Why the Tempo Works...
Tempo running improves a crucial physiological variable for running success: our metabolic fitness. "Most runners have trained their cardiovascular system to deliver oxygen to the muscles," says exercise scientist Bill Pierce, chair of the health and exercise science department at Furman University in South Carolina, "but they haven't trained their bodies to use that oxygen once it arrives. Tempo runs do just that by teaching the body to use oxygen for metabolism more efficiently."
How? By increasing your lactate threshold (LT), or the point at which the body fatigues at a certain pace. During tempo runs, lactate and hydrogen ions—by-products of metabolism—are released into the muscles, says 2:46 marathoner Carwyn Sharp, Ph.D., an exercise scientist who works with NASA. The ions make the muscles acidic, eventually leading to fatigue. The better trained you become, the higher you push your "threshold," meaning your muscles become better at using these byproducts. 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.
...If Done Properly
But to garner this training effect, you've got to put in enough time at the right intensity—which is where Roberts went wrong. Her tempo runs, like those of many runners, were too short and too slow. "You need to get the hydrogen ions in the muscles for a sufficient length of time for the muscles to become adept at using them," says Sharp. Typically, 20 minutes is sufficient, or two to three miles if your goal is general fitness or a 5-K. Runners tackling longer distances should do longer tempo runs during their peak training weeks: four to six miles for the 10-K, six to eight for the half-marathon, and eight to 10 for 26.2.
Because Roberts was focusing on the half-marathon, Tanser built up her tempo runs to eight miles (plus warmup and cooldown) at an eight-minute-per-mile pace. "The pace was uncomfortable," she says. "But after a while I realized, 'Oh, I can maintain this for a long time.'"
That's exactly how tempo pace should feel. "It's what I call 'comfortably hard,'" says Pierce. "You know you're working, but you're not racing. At the same time, you'd be happy if you could slow down."
You'll be even happier if you make tempo running a part of your weekly training regimen, and get results that make you feel like a Kenyan—if not quite as fast.
A classic tempo or lactate-threshold run is a sustained, comfortably hard effort for two to four miles. The workouts below are geared toward experience levels and race goals.
GOAL: Get Started Coach Gale Bernhardt uses this four-week progression for tempo-newbies. Do a 10- to 15-minute warmup and cooldown.
Week 1: 5 x 3 minutes at tempo pace, 60-second easy jog in between each one (if you have to walk during the recovery, you're going too hard).Week 2: 5 x 4 minutes at tempo pace, 60-second easy jog recovery Week 3: 4 x 5 minutes at tempo pace, 90-second easy jog recovery Week 4: 20 minutes steady tempo pace
GOAL: 5-K to 10-K Run three easy miles, followed by two repeats of two miles at 10-K pace or one mile at 5-K pace. Recover with one mile easy between repeats. Do a two-mile easy cooldown for a total of eight or 10 miles.
GOAL: Half to Full Marathon Do this challenging long run once or twice during your training. After a warmup, run three (half-marathoners) or six (marathoners) miles at the easier end of your tempo pace range (see "The Right Rhythm," below). Jog for five minutes, then do another three or six miles. "Maintaining that comfortably hard pace for so many miles will whip you into shape for long distances," says coach Toby Tanser.
The Right Rhythm
To ensure you're doing tempo workouts at the right pace, use one of these four methods to gauge your intensity.
Recent Race: Add 30 to 40 seconds to your current 5-K pace or 15 to 20 seconds to your 10-K pace
Heart Rate: 85 to 90 percent of your maximum heart rate
Perceived Exertion: An 8 on a 1-to-10 scale (a comfortable effort would be a 5; racing would be close to a 10)
Talk Test: A question like "Pace okay?" should be possible, but conversation won't be.