Just Add Intensity

May 2, 2004
Outside Magazine
Outside magazine, September 1999

Just Add Intensity
Ahtletes dread intervals because they're tough. They're also worth it.

By Terry Mulgannon


To your own heart be true

Interval training is a numbers game. for your hard work to pay off, you need to gauge your effort in relation to your maximum heart rate. The age-old formula for determining your max is to subtract your age from 220 if you're a man, 226 if you're a woman. But that's theoretical. If you want something concrete, you could drop several hundred bucks on a lab test, or do it yourself out in the field.

Slap on a heart rate monitor and warm up for 15 minutes in your endeavor of choice. During the next ten minutes, bump up your effort in two-minute increments. Eventually you'll top out at a number, with little doubt that it's your max: "Your arms will hurt and your vision will blur," says USA Cycling's Steve Johnson. "Literally." Consequently, you'd be best advised not to try this on the open road, so use a wind-trainer or a treadmill for running. If you're a swimmer, well, just be sure that the lifeguard is awake.

Now, to find your anaerobic threshold, subtract 20 from your max heart rate—again, an estimate. But there's a real-world test for your AT too. "Find a really long hill," says Johnson, "and ride or run up it at as fast a pace as you can keep up for half an hour. It's not a pace that'll feel good, but a pace you can sustain." After 15 minutes, you'll have the number that will serve as a benchmark for any sort of interval training. Finally, multiply your max by 0.70 to get your recovery rate. With these numbers in mind, you'll be able to torture yourself with newfound precision. —T.M.

It always sneaks up on you. despite the usual reassurances, what begins as a convivial workout with a friend all too often subtly takes on a competitive tenor. Say you're cycling. At the base of a canyon climb your friend silently pulls away and, just about the time your quadriceps implode in an effort to keep pace, disappears into the shadows. He eventually eases up, but the show of pity only makes it worse. Some artful prodding reveals that your pal, who devotes the same amount of time to working out as you, has recently sneaked in a bit of interval training—the bastard! He's quietly discovered that a simple regimen of sprinting in concentrated doses helps him perform dramatically better in those intense moments of effort that leave an athlete gasping like a drowning man and wincing as limbs turn to molten lead.

Painful, certainly, but rewarding like no other type of workout. Just ask Todd Williams, 30, America's best middle-distance runner, who won the national championships in the 15k last March. "Interval training's the only way to get faster," he says. It is also the most effective way to transcend those inevitable fitness plateaus. Indeed, it's no coincidence that when you become discouraged or bored with a routine, your performance has topped out. That's where intervals come in—instead of letting that hard-won fitness slide so you can feel good about building back up to peak power, it's time to punch through the ceiling and make some genuine improvement. Whether the race you're gearing up for is a spontaneous uphill bike sprint or a spirited run among age-group peers in a 10k, intervals will give you a fighting chance.

Under the Hood
Intervals are merely a tool to nudge your cardiovascular system from working aerobically—what most of us do most of the time when we run, ride, swim, or whatever—to working anaerobically in strategic bursts. "Anaerobic," of course, means your bloodstream isn't getting enough oxygen to help burn your body's fuels efficiently. The result is that the muscle cells start sucking up glucose to the exclusion of other energy sources, producing lactic acid. Pretty soon your system can't bail out the acid fast enough, and the buildup puts the brakes on muscle contractions, which is why you can't sprint indefinitely. "It's like using the afterburners on a jet," says Steve Johnson, an exercise physiologist who works with developing riders at USA Cycling and who has snagged eight national road-riding titles of his own. "You're wasting a lot of fuel, but that doesn't matter if you're trying to dodge a missile."

What interval training does is minimize this energy inefficiency by developing more capillaries, which remove lactate from your muscles. Stick with the training, and you'll notice more gain with less pain. "Interval training improves your body's ability to accelerate and to tolerate higher levels of lactic acid," adds Johnson, noting that an elite athlete can handle three times as much of the torturous substance as the rest of us.
Panting by Numbers
Before you dive into intervals, though, you need to have chalked up at least a month's worth of aerobic training, four or five hours a week—probably not an issue by this point in the summer. While aerobic training takes place in a range between 70 or 80 percent of your maximum heart rate, intervals will have you chugging along at about 90 percent (see "A Guide You Can Count On," below), a pace at or above your anaerobic threshold—the point at which your metabolism kicks into turbo-drive.

You'll start out performing just one interval session per week and then jump up to two, swapping them with aerobic days in your existing program. The idea is to go nearly all-out for a specified period and then to rest and do it again. Richard Quick, coach of the Stanford women's swim team, recommends experimenting with the variables of time, distance, rest, and repetitions, assembling different combinations to find your own best routine. "This is a highly individual pursuit," he emphasizes, "and you need to find out what works for you."

Whatever you do, don't confuse difficult with punishing. You want to accelerate into high speed smoothly, for instance, so you don't pop a tendon or tear a ligament. Lay off intervals every fourth week, and don't do them for longer than three months in a row. (You can pick up again after two months of typical training.) And if you're slowing down or feeling sluggish, take a few days off from all exercise. Eventually you'll start recovering—and performing—faster.

Quick also strongly suggests doing a little less than you think you can handle. "The worst thing that can happen is that you start to dread your intervals," he says. "You want to look forward to your next workout."
Reality Check
Of course, you're never going to love intervals. But to keep yourself motivated, says Todd Williams, try to balance the realities against a mind game. "I know it's always going to hurt," he says. "So I pretend it's a race and tell myself, 'This is it.'"

Though the underlying concepts are the same whether you run, ride, swim, skate, or cross-country ski, the benefits don't necessarily transfer from one sport to another because the most significant physiological changes occur within the exercising muscles. Accordingly, we've assembled interval routines for each of the three most popular forms of aerobic exercise: running, swimming, and cycling. They're drawn from the very same plans that Williams, Quick, and Johnson use, rendered manageable for those of us who aren't in training for the Sydney Games.

Finally, no matter which routine you use, be sure to keep close tabs on your health and diet. "When you're in good shape," says Johnson, "you walk a tightrope. There's this tension you experience: Am I training too much or not enough? But when it all comes together, you feel great."

You want me to do what? Getting up to speed the Swedish way.

Running is considerably tougher on your body than swimming or cycling, thanks to all the pounding and uneven surfaces. So it's important to ease into running intervals. The way to do that, says Todd Williams, U.S. national champion in the 15k, is to start out with the unfortunately named practice of fartlek training. Fartlek is a Swedish word meaning "speed play," a technique that entails throwing in quick bursts during the course of a typical run. "The thing about fartlek training," Williams says, "is that you can do it on any kind of terrain. You can surge on the uphills, take it easy on the downhills." It's an accessible way to get acquainted with running fast, and it provides a nice segue to sprinting on a track, which is where you should do full-fledged intervals. At the track, be sure to avoid sprinting off the line like Michael Johnson. Rather, run smoothly, giving yourself ten seconds or so to reach top speed. Skip intervals altogether every fourth week.

Weeks 1 and 2
One day a week, on your regular route, run at your anaerobic threshold for one minute, and then slow down until your heart rate drops to 70 percent of its maximum (see "A Guide You Can Count On," page 106). Repeat the sequence ten times. And as you should with each interval session, warm up and cool down for 15 minutes.

Week 3
From this point forward, bump up the intervals to twice a week, separating the days by at least 72 hours. On the first day, do a set of ten fartleks at two minutes apiece. For the second session, sprint for 30 seconds, recover, and then repeat this sequence three more times, tacking on 30 seconds to each interval. "The key thing," says Williams, "is to complete them—you want to succeed."

Weeks 5–7
For each week's first interval session, do three five-minute fartleks at your AT, jogging until your heart rate returns to 70 percent of its maximum between the high-intensity efforts. For the second session, find a 400-meter track and sprint once around. Jog for 200 meters, making sure your heart rate drops before starting again. Start with four intervals and add another each week.

Weeks 9–11
For the first session each week, run a mile just above your anaerobic threshold, give yourself a minute to recover, and do it once more. For the second session, at the track, sprint 400 meters six to ten times, jogging 100 meters between repeats.

Speedo notwithstanding, it's all about style

Don't even bother swimming intervals unless you have the stroke mechanics down. "You have to swim correctly before you can swim fast," says Richard Quick, U.S. swim coach for the 2000 Olympics. If you have poor running or cycling form, you may go 10 percent slower than you would if perfectly tuned. But because of the fluid medium, a mediocre swimming stroke can leave you bobbing along at half your potential speed. So if you're unsure of your efficiency, have a coach watch you swim and brush up with lessons if necessary (for more information, call U.S. Masters Swimming at 603-537-0203). Quick recommends that recreational swimmers use the freestyle stroke for their high-intensity work. Just remember to place your arm in the water with a straight wrist, palm tilted so the little finger hits the water first, and to pull your hand past your hips. Ideally, you should breathe on both sides, but if that's too awkward, breathe on one side going one direction, and the other on the return.

Week 1
On one day, after a 200-meter warm-up, swim 50 meters 20 times at your anaerobic threshold, stopping completely between repetitions and letting your heart rate drop to 50 percent of your max—regardless of how long it takes.

Week 2
Repeat the previous routine, but try to hold the rest time to no more than one minute. As you get more proficient, says Quick, "you play with the variables. First, change the distance, then the intensity, then decrease the rest interval."

Week 3
From now on, you'll be doing interval sessions two days a week, which should be separated by 48 hours. For each day this week, do your warm-up and then swim ten 100-meter legs at your AT, making sure to finish hard and trying to keep the rest to one minute.

Weeks 5–7
On both days, swim ten 100-meter intervals just above your AT with the aim of ratcheting down your rest time from one minute to 45 seconds over the course of these three weeks.

Weeks 9–11
Sprint 15 100s, while trying to bring your rest from 45 seconds down to 30 seconds by the 11th week.

Stand and deliver—and pray for a strong tailwind

Intervals need to be highly structured," says USA Cycling physiologist Steve Johnson. One splendid aspect of bicycles is that the available technology easily supports structured rides, with the help of speedometers, cadence counters, and of course the calibrated gradations of the gears. Johnson suggests getting started by finding a nice flat stretch of pavement on your road bike and warming up for 30 minutes. Use the big chainring up front and a medium gear in back, holding the handlebar drops, which puts you in the racing position.

Begin your sprint by jumping out of the saddle and pumping as hard as you can, rocking the bike side to side until you're up to about 90 rpm. (Just count the revolutions yourself if your computer doesn't have this function—it'll take your mind off the pain.) Then sit down and click through the gears until you hit the one that sets you on a course toward the heart rate you're targeting; you may not reach it until the last few seconds of the interval. Try to hold the same cadence throughout each bout. Now, slow down and keep pedaling comfortably until your heart rate drops down to 70 percent of your maximum. That's the time to start another interval. After each session, ride easy for another 15 minutes to cool down, and take a break from intervals every fourth week.

Week 1
Pick one of your training days and whip off five one-minute intervals at your anaerobic threshold. If that was easy, try up to ten. "Quality of effort is key," says Johnson.

Week 2
Repeat the first week. If, perchance, you were able to complete ten intervals and still felt reasonably fresh, says Johnson, "You're not working hard enough."

Week 3
From here on out, add a second interval day, making sure to separate the sessions by at least 72 hours. In the first, repeat the previous week's workout. In the second, increase the intervals to 90 seconds and drop back down to five.

Weeks 5–7
In the first day's session each week you'll be doing crisscrosses: Pedal for one minute just above your AT and one minute just below that mark, going back and forth five times. Then pedal easy for ten minutes and do another set. "It teaches you how to maintain a race pace," says Johnson, "and how to go hard when someone else makes you go hard."In the second day's sessions, start with five two-minute intervals and build up to ten over the weeks.

Weeks 9–11
Repeat the preceding routine, but on the first day do two sets of seven crisscrosses, and on the second day ride at your maximum heart rate for one minute, ten times, which will serve as a good gauge of your improvement since the first week.

© 1999, Outside magazine

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