Knowing your training zones is valuable if you want to prepare for a race. Some runners thrive in training by a rate of perceived exertion; however, many prefer to have clearly outlined pace or heart rate zones. One simple way to determine training paces is a recent race. But what if you have not raced recently or your last race was in extreme conditions? Enter the lactate threshold test, which you can do on your own, without visiting a lab.
The same applies to heart rate zones. Yes, you can subtract your age from 220; you can also throw darts at a board. While age-based formulas work well for some, for others, the standard deviation is just enough that you accidentally train in the wrong zones. The lactate threshold test can also provide customized heart rate training zones.
Based on an athlete’s goals and recent training and racing, I will sometimes prescribe the lactate threshold test. This provides us with accurate training paces and is easy to repeat. While this is a hard workout that demands recovery, this test also doubles as a solid aerobic stimulus.
The Science Behind the Lactate Threshold Test
Your running velocity at lactate threshold (vLT) is approximately your one-hour race pace. Typically, you utilize either laboratory tests or recent race paces in a calculator (ideally the VDOT calculator) to determine vLT. However, that’s not the only method. A 2005 study conducted at East Carolina University found that a 30-minute time trial on a flat surface estimated vLT just as well as other tests, thus making it a practical test for real-world athletes.
Many coaches do use this test, from triathlon coach Joe Friel to ultra coaches Megan & David Roche to myself. It’s simple, practical, and cheap! Additionally, many athletes experience a huge confidence boost seeing where their fitness is.
How to Do a Lactate Threshold Field Test:
- Warm up with 10-20 minutes easy, with 3-4 strides (20 second long accelerations)
- Pause for a moment and let yourself focus. Keep this 1-5 minutes in length; you don’t want to cool down.
- Run 30 minutes as hard as you can, aiming for a consistent effort. You want to avoid starting too fast; epically crashing and burning nullify the test. You want to save this as a separate GPS recording.
- Cool down for 5-20 minutes, depending on goal mileage for the day.
A few notes for accurate results:
- Choose a flat, uninterrupted route. If you are repeating the test, use the same route. Do not choose an over hill route or a straight downhill route. If in doubt, use a track.
- If possible, run it on a day with mild weather (avoid high heat, high humidity/dew point, snow/ice, and heavy winds).
- Run alone! This is a time trial, not a race.
- Use a chest strap if you are using this test to determine HR zones. An optical wrist-based HR monitor simply is not accurate enough for this test.
What to Do with Your Result:
Your average time from the test is your velocity at lactate threshold (vLT). From there, you can calculate your training paces.
- Easy: 1.5-2.5 minutes per mile slower than your vLT
- Marathon pace: 30-40 seconds per mile slower than vLT
- Half marathon pace: 10-15 seconds per mile slower than your vLT
- Threshold (hour race effort): vLT pace, plus/minus 5-10 seconds per mile
- Critical velocity (30-40 min race effort): 10-15 seconds per mile faster than vLT
- VO2max/interval: 40-45 seconds per mile faster than vLT
Your average heart rate in the final 20 minutes is your heart rate at your lactate threshold (LTHR). You can use this to accurately calculate your heart rate zones for training.
- Zone 1: Less than 80% of LTHR
- Z2: 80–88% of LTHR
- Z3: 89–95% of LTHR
- Z4: 96–99% of LTHR
- Z5: 101%+ of LTHR
You can repeat a lactate threshold test every six to eight weeks. However, avoid doing the test within six weeks of a goal race. Most importantly, treat the test like any hard workout: program easy runs or rest in the couple of preceding days and then be deliberate about recovering well.
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