by Fred Matheny
If you read articles about training (or hear other cyclists talk about their training programs) you can’t avoid the term “lactate threshold” (LT). It’s so common it has become a buzzword, as in “What’s your LT?” or “I went over my LT on that hill and blew up.”
Lactate Threshold (LT) Defined
Lactate threshold is the exertion level beyond which your body can no longer produce energy aerobically. Additional intense work means your body can’t deal with the resulting buildup of lactic acid (lactate). Excess lactate is marked by muscle fatigue, pain and shallow, rapid breathing. LT was formerly called anaerobic threshold (AT) but this designation is now dated. In scientific papers it’s sometimes referred to as OBLA (onset of blood lactate accumulation).
How Lactate Threshold Is Measured
LT can be measured in the lab with a relatively simple but invasive procedure. On a stationary bike, the cyclist rides at steadily increasing resistance while the lab technician takes a blood sample from his fingertips every minute. Lactate circulates in the blood and LT is defined as a specific arbitrary amount—usually 4 millimoles.
LT also can be measured, although not quite as accurately, on the bike—and you won’t have to suffer getting your fingertips perforated. Basically, LT is the maximum intensity a rider can sustain for a 30- to 60-minute time trial. This intensity can be measured in watts or heart rate. Ground speed, the simplest method, can be deceiving because it takes more power to ride at, say, 25 mph into a headwind than with a tailwind.
To determine your lactate threshold, wear your heart monitor or use a power meter, warm up thoroughly, then ride a time trial of at least 10 miles on a flat course. Your average heart rate for the distance is your LT. (It’s ideal to have a heart monitor that calculates average heart rate.) To double check, do this test again at least one week later. Try to be well rested for each test.
CAUTION! Lactate threshold testing and LT training are extremely strenuous. Please get your doctor’s approval, especially if you are over 35, have any type of cardiovascular problem, or are not used to this type of exertion. Play it safe so you can ride with confidence.
Why is Lactate Threshold Important, Anyway?
The more power you can generate without going over your lactate threshold and becoming anaerobic, the faster you can go at a given heart rate.
EXAMPLE! Suppose Mick generates 300 watts at LT while Rod puts out 250. On a race’s early hills, Mick pushes the pace at an effort equal to 280 watts. He’s still under his LT, riding hard but in control. To keep up, Rod has to go over his LT and into oxygen debt. On the last and deciding climb, guess which rider still has something left?
This is all fine for racers, but why is LT important for a recreational rider? The ability to produce more power at a comfortable heart rate means you’ll go faster with the same effort. Your time for centuries will improve. When your companions on the Sunday morning group ride are gasping on a climb, you’ll still be in your comfort zone.
The Carmichael Secret
LT’s significance for all riders has risen because it’s been identified as the key component in competitive cyclists’ training programs.
Way back in 1999, cycling coach Chris Carmichael presented his explanation of why his most successful clients were able to gain incredible levels of fitness and win so many events. A group of medical professionals heard Carmichael’s talk at the Boulder Center for Sports Medicine’s Science of Cycling Seminar. What the coach revealed—and its significance for recreational riders—has been under-appreciated.
First, a little background. Most training programs are complicated because cycling requires a vast range of seemingly conflicting abilities—the endurance to ride 150 miles, the power to win 53×12-gear sprints, and the aerobic capacity to time trial at better than 30 mph. Training these diverse skills is like asking a champion marathoner to also win the 100-meter sprint or an NFL quarterback to play nose tackle, too.
However, Carmichael’s training is extremely simple. He has distilled the sport to one skill—the ability to produce great power at lactate threshold.
“The issue,” Carmichael stated at the conference, “isn’t merely to produce power. Anyone can produce 400 watts. But most riders can’t produce 400 watts for very long without going anaerobic and slowing abruptly. “Power isn’t the issue. It’s the ability to produce significant power while remaining under your LT and in control.”
Many of Carmichael’s training recommendations revolved around raising a rider’s power at lactate threshold.
“The secret,” Carmichael concluded, “is to do most of your hard training a little below, at, or slightly above your lactate threshold.”
Workouts to Improve Your Lactate Threshold
Here are typical workouts to boost lactate threshold. Remember to warm up for at least 15 minutes. Wear a heart monitor or use a power meter to regulate your effort.
• LT TEMPO Ride for 30 minutes at an average heart rate about 10 beats below your LT heart rate.
• TWO TENS Ride for 10 minutes at an average heart rate about 5 beats below LT. Spin gently for 15 minutes, then repeat the 10-minute hard effort.
• HILL REPEATS Find a hill that takes 3-5 minutes to climb. Go up at your LT heart rate. Coast to the bottom, spin gently for 5 minutes on the flats, then repeat the climb 2-5 times, depending on your fitness level.
• GRINDERS Find a long climb that takes 10-30 minutes. Ride it steadily at your LT. Choose a gear that allows you to maintain a relatively high cadence of 80-90 rpm.
• TIME TRIALS Many bike clubs have a time trial series. They’re usually around 10 miles on a weekday evening. Check at your local bike shop for details. Riding these events is great LT training—and you’ll have the benefit of competition to give the hard effort another purpose.
Take Caution with Lactate Threshold Workouts
• We mortals don’t have as much time to train and recover as pros, so do only two LT workouts per week, separated by at least two rest days.
• After three weeks of LT training, ride easily for an additional week to let your body recover and consolidate the gains you’ve made from hard training.
• Don’t do LT training all year. After eight weeks of lactate threshold work (two cycles of three weeks of LT training twice a week, then one week easy, as just described), spend at least a month riding steadily at about 30 beats below LT to build your endurance.