Bodywork, April 1997
You've been training for what, a month or two now? Seems as though that snappy new fitness plan has all the neighborhood jocks lapping at your heels. Your cardiovascular abilities must be formidable, with your schedule of running and swimming six days a week. And hitting the gym on weekends certainly doesn't hurt the physique, eh? There's that race coming up in a month, and you're clipping along at a post-Independence Day pace. In short, it's looking like a good season indeed--with one caveat. Whether you're sprinting the last 40 yards to your driveway or pushing to stay with the pack, you're certain to run headlong into something that your precious endurance regimen didn't account for: lactic-acid hell.
No doubt you've been there before. "You'll feel a burn in your muscles, and your leg turnover will become sluggish," says Saul Blau, a white-smocked exercise physiologist who tests athletes at Health Corp., a sports medicine center in Irvine, California. "Your vision will start to narrow, and of course, you'll be gasping for air. Then the leg pain comes. No one escapes." Cue dirge, please.
Despite Blau's apocalyptic tones, getting burned by lactic acid isn't to be feared, but embraced--or at least managed. Regardless of whether you're trying to regain your youthful fitness or gunning for a higher finish in that "fun" 5k, coping with lactic acid merits serious attention. Because for most athletic endeavors--those under two hours in length--running out of fuel is rarely the cause of poor performance. Rather, it's the buildup of lactic acid that'll thwart your efforts, causing muscles to fatigue, burn, and finally seize up.
The problem is, such attacks have no sense of timing. You'll be chugging along on a run, everything hunky-dory, when you encounter a steep hill, or speed up to catch your dog, or try to beat a flashing don't-walk signal. Up until then you'd been sucking in oxygen to help turn carbos and fat into energy, but when you crank up the speed, your effort eventually outstrips your lungs' ability to replenish your muscles with oxygen. With no way to create energy, your body panics and starts looting your already limited energy stores, a process that produces an unfortunate by-product: lactic acid. "You're going off the deep end," Blau says. That point of departure is called your anaerobic threshold, or AT.
Happily, any athlete can significantly raise his AT, pushing back the point when lactic acid is created and giving you more time to kick before the system eventually shuts down. "With proper training we see phenomenal improvements, as much as a 20 percent increase in anaerobic threshold in three months," Blau says. "You'll be able to go a lot faster with less pain."
Now the bad news: Learning how to beat back lactic acid will hurt plenty--especially at this vernal stage of your program, when no matter how impressive your endurance base, you can't exactly pass for speedy. "You have to train at or above your anaerobic threshold to change it," Blau says. This, we're sorry to say, involves an unpleasant but ultimately rewarding technique: intervals.
First you need to measure your AT heart rate (see "Testing Your Limits," page 138). Once you figure that number, which isn't to be confused with your maximum heart rate, you'll use it to optimize your interval training. The sessions have to be precise--just over the redline, but not too far, lest you blow a gasket.
Blau suggests specific guidelines to improve with minimum risk. For shorter intervals--say quarter-miles at the track--run at a pace 7 percent faster than race pace. For instance, if you typically run a 6:30-pace in a 5k, you'd shoot for time of 1:45 in the quarter. For longer intervals, you'll want to ease off the pace, so that if you're doing miles, you might want to run 3 percent faster than your usual pace.
In a pool, where you can't keep your eye on a heart rate monitor, do 100-yard sprints and take your pulse after each one to make sure you're not loafing. Or, instead of judging by distance, you could build up to your AT heart rate and simply try to hold the pace for one minute--a technique that works well if you prefer biking or in-line skating.
Regardless of the type of interval you choose, it's easy to tell when your workout is over; your body has a self-regulating system that will politely notify you when you're finished. Here's how it works: After each interval, you'll want to continue walking, treading water, or slowly pedaling, all the while watching your heart rate. What you are looking at is a recovery ratio; typically, you want a two-to-one work-to-recovery equation. So if your interval--the length of time you work at your target heart rate--takes two minutes, you'll walk for one minute. When the minute's up, check your heart rate again. That number is your guide; the first time your heart rate fails to drop to this number on subsequent intervals, that's the moment to call it quits. Cool, huh? And don't push it. "If you keep going," cautions Blau, "you're looking toward injury, incomplete recovery, and overtraining."
This is obviously rough stuff--bludgeoning heart, mind, and fragile connective tissue--and should be used sparingly. If there's a particular event you're preparing for--speed-hiking Colorado's Longs Peak, playing in a summer volleyball tournament, running a local race--start your interval training four to six weeks in advance. Once a week will do for folks interested only in recreational fitness; if you're the type who'd stare down his mother at the starting line, you might opt for two interval sessions a week, with at least one day of active rest in between.
If you do race, keep your heart rate just a few beats under your AT until you have the finish in your sights, and then punch it. Drop too far below the line and you'll have a perfectly merry, albeit slow, time. If you spend too much time over your AT, you'll spend so much time recovering that you'll actually lose ground.
The key is to trust your body. "Very often when the lactic acid is building up and you're beginning to slow down, you fight it," says Frank Shorter, marathon gold medalist at the 1972 Olympics and now a fearsome masters competitor. "A lot of athletes think this is when you have to push harder. What you really need to do is relax and ease up just a little to recover." And if you've been doing your intervals, you shouldn't have any problem beating your mom to the finish.
Ken McAlpine contributes often to Outside's Bodywork pages.