Find Your Lactate Threshold … By Talking

A low-tech tool for exercise prescription isn’t just for beginners anymore.

If you have exercised more than three times in your life, then you have probably heard of the talk test. Developed by exercise scientists who sought to come up with a simple way for non-athletes to monitor and control exercise intensity, the talk test is just that. More precisely, it’s a rule of thumb that exercisers can use to choose an effect yet comfortable effort level for steady-state aerobic workouts. The rule is this: if you can talk very easily while you’re working out, you’re not working hard enough. If you can’t talk comfortably, you’re going too hard. And you are only just able to talk comfortably, you are working at the right intensity.

What is the right intensity? Again, the talk test was designed mainly for the benefit of elderly, overweight, and other non-athlete exercisers who wanted to get results from exercise without experiencing any more discomfort than necessary. Research suggests that an individual needs to exercise at or above 55 percent of his or her maximum heart rate to gain a benefit. But to remain comfortable, the exerciser must stay below his or her “ventilatory threshold” heart rate, which means below roughly 80 percent of maximum heart rate in the average person. The talk test was designed to keep the exerciser between these boundaries.

Back in 2004, the talk test was validated as a tool to locate an exercise intensity close to the ventilatory threshold. Here’s how the protocol works: subjects are asked to walk or jog on a treadmill or ride an exercise bike while reading the pledge of allegiance. After completing it they are asked if they were able to do so comfortably. Then the exercise intensity is increased slightly. This continues until the subject reports that he or she was unable to complete the pledge comfortably. The highest exercise intensity at which the subject is able to complete the pledge comfortably is identified as the ideal exercise intensity. An early validation study of the talk test found that it coincided almost perfectly with the ventilatory threshold. This was not surprising, because the ventilatory threshold is the intensity of exercise at which respiration spikes, and spiking respiration is the very thing that makes it difficult to talk during exercise.

RELATED: Go By Feel, Skip The Lactate Threshold Test

A new study compared the talk test to both the ventilatory threshold and the somewhat more intense lactate threshold. Researchers at the University of New Hampshire were surprised to discover that results of the talk test in student volunteers were more closely associated with the lactate threshold than with the ventilatory threshold. The researchers noted two thresholds in the talk test: one was the highest exercise intensity at which talking was comfortable; the other was the slightly higher exercise intensity at which subjects reported that speaking was only somewhat comfortable. The highest comfortable speaking intensity fell at or a bit below the lactate threshold for most subjects while the intensity at which they were uncertain of their comfort in speaking fell at or slightly above the lactate threshold. But both talk test thresholds fell above ventilatory threshold intensity.

These results are of special interest to runners, who are encouraged to regularly perform a small amount of training at lactate threshold intensity. The lactate threshold intensity of exercise is higher, hence less comfortable, than the ventilatory threshold intensity, but it also yields greater gains in aerobic fitness. Thus, if the talk test is a better predictor of the lactate threshold than it is of the ventilatory threshold, it may be a better tool for competitive runners than it is for non-athlete exercisers.

An invasive laboratory test is required to pinpoint the lactate threshold. But if something as simple as the talk test can be substituted for a trip to the exercise lab — and that now appears to be the case — then runners can easily find the right intensity for threshold workouts on their own.

RELATED: What’s The Ventilatory Threshold?

I recommend performing a more formal talk test on a treadmill or running track or on a smooth, flat road while wearing a speed and distance device. After warming up, run at a steady, easy pace while reciting the Pledge of Allegiance. If it’s comfortable, increase your pace by a modest amount — roughly 15 seconds per mile — wait about a minute to physiologically adjust to the new tempo, and recite the pledge again. If it’s still comfortable, increase your pace by a moderate amount again. Continue until you can no longer recite the pledge comfortably. Note your pace at the last stage in which speaking was comfortable, or sort of comfortable. That’s your current lactate threshold pace. If you’re wearing a heart rate monitor you can note your current lactate threshold heart rate too. And if people start looking at you funny, don’t worry about it!

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About The Author:

Matt Fitzgerald is the author of Iron War: Dave Scott, Mark Allen & The Greatest Race Ever Run (VeloPress, 2011) and is a Coach and Training Intelligence Specialist for PEAR Sports. Find out more at mattfitzgerald.org.