The concept of the “Talk Test” as a marker of correct exercise intensity has been around for a pretty long time. In fact, it has been around at least since 1939, when Professor John Grayson at Oxford University advised English mountaineers to “climb no faster than you can talk.”

This simple idea kept kicking around on the fringes of exercise physiology, not quite technologically advanced enough to ever gain real respectability in an era of rapidly expanding technology, but never quite going away. It was included in the fourth edition of ACSM’s Guidelines for Exercise and Training in 1991, and in guidelines published by the American Council on Exercise in 1997. But despite official recognition by the major professional societies, the Talk Test never quite achieved the respectability of the Karvonen Method or the glamour of the newly emerging exercise-prescription techniques such as %VO2max, ventilatory threshold, or techniques based on analysis of blood lactate.

In the late 1990s, Dr. Robert Goode at the University of Toronto began promoting the “hear your breathing test,’ and Dr. Steven Keteyian and colleagues at Henry Ford Hospital in Detroit demonstrated that if people could still talk well enough to answer questions to a structured interview (e.g., What did you have for breakfast this morning?), they were in a range of heart rate or VO2 that fit the exercise prescription guidelines of ACSM.

Following years of research, it became clear that not only did the Talk Test provide an accurate but very simple marker of more complex physiologic processes, it might even help guide exercise prescription. These early results are summarized in Figure 1, which shows that below the ventilatory threshold, comfortable speech is usually possible (green zone); that right at the intensity of the ventilatory threshold comfortable speech becomes equivocal (yellow zone); and right at the respiratory compensation threshold, comfortable speech becomes impossible (red zone).

Making exercise safer

for cardiac patients

Graduate students at the Mayo Clinic administered the Talk Test during diagnostic stress tests at a local hospital. They selected 20 tests that the attending physician had diagnosed as consistent with exertional myocardial ischemia (e.g., a “positive’ exercise test). All of these patients had reached the equivocal stage of the Talk Test before the first appearance of electrocardiographic abnormalities, based on either workload or heart rate. In fact, the difference in heart rate from the last time they could speak comfortably and the first electrocardiographic abnormalities was about 10 beats per minute, the same margin that the ACSM Guidelines for Exercise Testing and Prescription recommends for prescribing exercise in patients with exertional ischemia. These were very exciting findings, because they suggested that if people could talk during exercise, then it was unlikely that they had exertional ischemia. Importantly, the biggest safety concern in clinical exercise programs could be addressed with a very simple technique.

The talk test can be the primary means of measuring exercise intensity for people who do not have typical heart rate responses to graded exercise. These people include those on beta blocker medications, some cardiac and diabetic patients, pregnant women, and others who may have an altered heart rate response.

Digging deeper

into the talk test

Follow-up studies have demonstrated that if the exercise intensity is only slightly above the ventilatory threshold, it takes two to four minutes to be able to lose the ability to speak. However, the basic relationship—below ventilatory threshold, speech is comfortable, and above ventilatory threshold, speech is not comfortable—remains valid.

Again further tests found that the changes in ventilatory threshold and the Talk Test responses were highly correlated: When the ventilatory threshold got better, then the workload eliciting the Talk Test got better.

Thus, as unlikely as it might seem, we’ve known for decades how to prescribe exercise using the Talk Test. You may be able to replace your heart rate monitoring with this simple test during all of your workouts, or at least when counting your pulse is inconvenient. Try your own Talk Test during your next workout (and compare it to your Target Heart Rate if you’re skeptical). Not only does the Talk Test provide a very useful tool for establishing and monitoring exercise intensity, but it may also contribute to the safety of exercise training.

The graph above illustrates the relationship between ventilatory threshold, anaerobic threshold, and the ability to “talk.” The green zone represents the appropriate exercise-training zone where individuals have a “positive” talk test, indicating that they can still speak comfortably. The yellow zone corresponds to the point where speaking begins to become difficult—the “equivocal” stage of the talk test. Exercising at this intensity is difficult and cannot continue indefinitely. The red zone, which corresponds to the point where smooth conversation becomes impossible, is the “negative” stage of the Talk Test and exercising at this level rapidly results in fatigue.

Richard Geres is an ACE-certified Personal Trainer

www.richardgeres.com