Aerobic exercise is a decisively important component of any fitness program. However, establishing and maintaining ideal exercise intensities for optimally safe and effective workouts can prove challenging for both exercisers and fitness professionals.
In designing cardiorespiratory exercise programs, it is meaningful to consider that many people engage in aerobic exercise to control weight, improve their health status or reduce their disease risk. Knowing your client’s goals and purposes for doing aerobic exercise helps to determine the appropriate intensity, frequency, duration and progression of the exercise program.
Traditionally, aerobic exercise program intensities have been developed around accepted standards of percentages of maximum heart rate and oxygen consumption (VO2). For instance, the American College of Sports Medicine (ACSM) recommends 55%–90% of maximum heart rate or 40%–85% of maximum VO2 for most individuals (ACSM 1998). Although the success of these techniques has been consistently demonstrated, many fitness enthusiasts find the necessary objective monitoring (e.g., continuously checking heart rates) difficult and sometimes tedious.
Recent studies have helped validate an easier way to stay on track: the “talk test.” This method appears to be a simple way of maintaining recommended exercise intensities while avoiding the problems of the more involved practices of heart rate and VO2 assessment (Persinger et al. 2004).
The talk test was developed to be an informal, subjective method of estimating appropriate cardiorespiratory exercise intensity. The method entails maintaining an intensity of exercise at which conversation is comfortable. When an exerciser reaches an intensity at which he or she can “just [barely] respond in conversation,” the intensity is considered safe and appropriate for cardiorespiratory endurance improvement. The newest research supports the usefulness of the talk test and highlights its ability to closely reflect actual heart rate and VO2 levels (Persinger et al. 2004).
The study by Persinger et al. examined the consistency and effectiveness of the talk test as a tool for exercise program design on the treadmill and the cycle ergometer. The researchers hypothesized that the ability to vocalize would correlate positively with aerobic exercise intensity on both of these modes of exercise.
Ten male and six female participants (average age = 24 years) volunteered to participate. All subjects were considered healthy and moderately active. Participants were prescreened for contraindications to exercise testing prior to the study.
All participants performed four separate exercise tests, completing two assessments on a treadmill and two on an electronically braked cycle ergometer. The tests were performed on different days, at the same hour each day. The order of testing was randomized.
The exercise protocol was designed to best meet each participant’s individual exercise capacity. To accomplish this, the treadmill speed was set at a pace at which participants subjectively felt they could comfortably walk or jog “virtually indefinitely.” Intensity was then increased with grade (incline) increments every 2 minutes. Likewise, the initial cycle ergometer power output was 25 watts (W), increasing by 25 W in 2-minute stages. Participants who weighed less than 60 kilograms (approximately 132 pounds) had a starting power output of 20 W, increasing by 20 W in 2-minute stages.
Each participant performed to exhaustion one cycle ergometer test and one treadmill test. Throughout these tests, the researchers monitored heart rate using radio telemetry (a heart rate monitor); they also collected respiratory data using open-circuit spirometry.
Each of the other two tests involved a talk test, with subjects reciting the Pledge of Allegiance during the last 30 seconds of every 2-minute exercise stage. After recitation, the participants were asked if they could “speak comfortably.” They were permitted to answer yes or no. However, if they responded in an uncertain manner, they were recorded as being “equivocal” (meaning unclear or questionable) and not able to speak comfortably. When they answered no, the exercise test was terminated. Actual measurements of VO2, ventilatory threshold and heart rate were compared to the responses made during the talk test. (See “Ventilatory vs. Lactate Threshold,” above.)
The results of this study showed a close correlation between the talk test, VO2, ventilatory threshold and heart rate on both the cycle ergometer and the treadmill. This denotes the usefulness of the talk test as a simple way of determining appropriate intensity for both of these exercise modes. It appears that by using just the talk test—without relying on more invasive or difficult procedures—one can achieve the proper intensity of exercise. When comfortable speech was just barely possible (the last exercise stage where researchers received a yes answer or the “equivocal” stage), the exercise intensity was within the suggested guidelines for exercise program design based on the subject’s VO2 and heart rate data. However, when comfortable speech was no longer possible, the exercise intensity was greater than what is normally recommended for exercise intensity and above the ventilatory threshold. Therefore, ventilatory threshold was highly correlated with the last positive and equivocal stages of the talk test.
The most practical application of this research is for establishing and maintaining ideal exercise intensities without the demand of expensive laboratory equipment or confusion with pulse check counting. It allows an exerciser and his or her trainer to make use of a subjective intensity assessment, permitting a quick, easy and accurate evaluation of exercise intensity. Although no specific guidelines for the talk test yet exist, we recommend using it in a manner similar to heart rate monitoring—at least once every 15 minutes of aerobic exercise. During group exercise conditions, the talk test may be particularly useful. The instructor can readily have students subjectively monitor their exercise intensity by having them cite the Pledge of Allegiance. For students from other cultures, we recommend asking them to cite a familiar nursery rhyme, as it has been our experience that most cultures have nursery rhymes that exercisers readily know. Remember, if the aerobic participants can “talk the talk while walking the walk” (with a little challenge or difficulty), it is likely that they are achieving the appropriate exercise intensity.
Exercise physiologists have long used ventilatory and lactate thresholds as laboratory indicators of exercise performance and intensity. Ventilatory threshold describes a nonlinear increase in respiration that corresponds with higher levels of exercise intensity. Until ventilatory threshold is achieved, respiration increases linearly with intensity. However, as soon as ventilation breaks from this progressive linear increase, ventilation threshold has been established. By contrast, lactate threshold refers to a point during exercise of increasing intensity at which blood lactate begins to accumulate above resting levels. This occurs when the body’s ability to clear lactate is surpassed by its accumulation.
When the ventilatory and lactate thresholds are surpassed, exercise performance cannot be maintained at a steady state and so fatigue soon occurs. There is therefore a great interest in training strategies that delay the onset of the lactate and ventilatory thresholds. Although many fitness professionals think of these thresholds as synonymous, they are in fact very different and can occur at substantially different exercise intensities in the same individual. The most recent research supports the use of the lactate threshold as the best predictor of endurance performance (Dalleck & Kravitz 2003).
Dalleck, L.C., & Kravitz, L. 2003. Optimize endurance training. IDEA Personal Trainer, 14 (1) 36–42.
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