Chances are, you’ve heard cyclists say they’re “training at ninety percent of max heart rate,” or some similar figure. Sounds kind of impressive, doesn’t it? After all, athletes like to do everything to the max. Although maximum heart rate is a useful benchmark for determining how intense your training is or should be, it actually isn’t as effective as using your lactate threshold.
Lactate threshold is the border between high- and low-intensity work, or roughly the effort experienced in a flat-out, 30-minute time trial (more on this later). It’s a better baseline than maximum heart rate for determining training zones, because two cyclists with the same maximum heart rate may have widely varying lactate thresholds due to genetic or training differences. Sedentary people can have lactate thresholds as low as 50 percent of maximum heart rate, while elite athletes can maintain 90 to 95 percent for an hour.
“For the longest time, everyone focused his or her training around max heart rate,” former USA Cycling coach Margaret Kadlick told Bicycling. “Now we know lactate threshold is much more important. When you raise your lactate threshold, you can produce more power at a comfortable heart rate, and that makes you a better rider and racer in every situation.”
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Below, we cover everything you need to know about this incredibly useful training measure—including how to find and raise your lactate threshold, to help you become the best rider that you can be. (Of course, it’s always best to work with a doctor or professional before attempting any new self-tests at home.)
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What Is Lactate Threshold?
Lactate, your body’s buffering agent, neutralizes the acid that builds up in your legs and makes them burn during heavy exertion. The harder you turn the cranks, the faster acid accumulates. Eventually, your muscles generate more acid than you can neutralize, and your searing muscles force you to ease up. The point at which you begin to accumulate acid more quickly than your body can dissipate it is your lactate threshold, or, in riding terms, the fastest pace you can maintain for 30 minutes without feeling like your legs are on fire.
Fortunately, it isn’t hard to determine your lactate threshold.
How to Find Your Lactate Threshold
In the Lab
Many coaches, gyms, and performance centers offer a lactate threshold test, which usually takes 30 to 40 minutes. While wearing a heart rate strap, you’ll start pedaling easily on a stationary bike set up for a specific power output. Every few minutes, the resistance increases until you can no longer keep going. At each increase, the technician pricks your finger for a drop of blood, which a machine then analyzes for lactate, or lactic acid—the prime marker of muscular fatigue. All the data is logged via a computer, which plots the graph of your results. You can also get your lactate threshold in a VO2max test in a similar setting.
30-Minute Time Trial
Most likely, you won’t find yourself hangin’ with the pros in a lab though. But you can find your lactate threshold with a DIY time trial, that’s best done outdoors on a flat road.
Map a three-mile route that you can ride without stopping. Strap on a heart rate monitor, warm up for 20 minutes, then ride the route at the fastest pace you can sustain. Recover for 10 to 20 minutes (ride back to the start of your route at an easy pace). Repeat the test. Your lactate threshold is approximately the average heart rate of the two efforts. (More accurately, it’s 103 percent of that figure.) Jot down your times and average paces; repeat the test in eight weeks to see your progress.
Indoor Test at Home
You can also find your lactate threshold at home with this indoor workout test. First, calculate a range from 80 to 90 percent of your maximum heart rate. So for instance, if your maximum heart rate is 180 bpm, 80 percent is 144 bpm and 90 percent is 162 bpm. Most cyclists’ lactate threshold will be somewhere between these two numbers, depending on conditioning.
Once you’ve estimated your lactate threshold range, perform an indoor test to find what resistance or gear keeps you in your lactate threshold range while pedaling at a constant 90 rpm. (You’ll need a cadence function on your power meter or indoor set up, a bike computer, your heart rate monitor, and a friend.) Warm up well, then maintain 90 rpm in your chosen gear. Pedal for 15 minutes and have your helper jot down your heart rate each minute. If you’ve chosen a gear that’s too high (your heart rate soars, and you gasp for breath), stop, decrease gearing, and do another test on a different day using a lower gear.
When you complete a test during which you are pedaling at the highest gear that allows your heart rate to stay fairly level over the 15-minute test, note that heart rate—it will be very close to your lactate threshold. But remember not to go too easy; you are trying to find the highest heart rate you can maintain for 15 minutes, so your breathing should become moderately labored.
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Now—and this is important—when you’ve found your final number, subtract two to five beats to get your final figure. Why? Because most cyclists overestimate their lactate threshold, resulting in training ranges that are too high. Test your estimate on rides. How does this intensity feel? Can you maintain your goal heart rate? Remember that this isn’t a precise science; you’re merely trying to find a good number upon which to base your training plan. By following these steps, you can get an accurate home measure of their lactate threshold within a couple of beats per minute.
Once you determine your individual lactate threshold, every workout can be based on a reference point that yields safe, repeatable, and focused cycling training that’s tailored to your fitness level at that moment.
How to Raise Your Lactate Threshold
Like most things body-related, lactate threshold is partially genetic. But it’s also quite trainable. By systematically pushing your limits, you can help your body become more efficient at clearing and buffering lactic acid.
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The trick is riding that razor-thin edge between the point where you can ride comfortably for hours and where you can sustain only a few minutes before frying. “It’s important that you have plenty of base miles and some speedwork under your belt before you start lactate threshold training,” says Kadlick. The bigger your aerobic engine when you begin, the better your results will be.
The following drills are designed to raise your lactate threshold. Choose one drill per workout, and do lactate threshold training no more than two days a week, preferably not on consecutive days.
Steady State Intervals
After a good warmup, ride 10 minutes at a steady effort, keeping your heart rate three to five beats below your lactate threshold heart rate. Recover for 10 minutes, then repeat two more times.
“Once you’re comfortable at this level, do two 20-minute, steady-state efforts, recovering for 20 minutes in between. Eventually, work up to one 30-minute effort,” suggests Kadlick. “This is the most effective way to increase power at LT.”
Up And Down Intervals
These intervals blend lactate threshold and VO2 max (your body’s ability to process oxygen) training to simulate the effort you need when racing on a hilly course, where you have to push beyond your lactate threshold for short surges then clear the acid and recover quickly.
First, warm up. Then pick up the pace to your lactate threshold heart rate and hold that intensity for five minutes. Push it to about three to five beats above your lactate threshold for one to two minutes, then drop it back down. Continue for a total of three cycles, or about 18 to 20 minutes.
Lactate Threshold Tolerance Intervals
Crit and mountain bike racers need to elevate their “suffering threshold” as well as their lactate threshold, because those situations demand pushing past lactate threshold and holding it there for extended bursts over and over. By training at an intensity where your body can’t clear the lactate, you’ll boost your ability to keep riding hard in the face of high lactate levels.
After a thorough warmup, increase your effort to about five beats above your lactate threshold heart rate. Hold it there for two to three minutes. Reduce your effort for 60 to 90 seconds, just long enough so you feel partially recovered, but not quite ready to go again. Repeat three times.
Part of this article was originally published in The Big Book of Training.
