Submaximal Exercise Testing
Objectives for Laboratory 7
- Reinforce the terminology and techniques associated with measuring blood pressure at rest and during exercise.
- Learn the skills needed for administering two types of submaximal exercise tests.
- Reinforce the terminology and techniques associated with measuring heart rate at rest and during exercise.
- Estimate VO2max by the measure of HR response to submaximal exercise.
Submaximal Exercise Testing
Knowing a subject's cardiorespiratory capacity, or VO2max, can be useful for exercise prescription or diagnostic purposes in at-risk populations. Tests for estimating VO2max can be maximal (i.e., involving incremental workloads to the point of failure; see the following laboratory) or submaximal (i.e., ending before extreme exertion). Submaximal estimates of cardiorespiratory capacity can be more practical because they do not require expensive automated metabolic laboratory equipment and trained personnel. However, they do require some knowledge and skill to carry them out properly. Many submaximal tests exist, and they differ by target population, duration, and modality (e.g., bikes, treadmills). Depending on the submaximal tests protocol, you may be required to monitor HR (heart rate), BP (blood pressure), patient symptoms, time, ergometer work rates, and Rate of Perceived Exertion (RPE). The most important one for this Laboratory activity will be monitoring HR.
The Relationship between Heart Rate and Oxygen Consumption
In non-disabled individuals, heart rate and oxygen uptake have a linear relation up to submaximal workloads. The figure below shows the outputs obtained from a VO2max test. Notice how closely related exercise responses are between VO2 (red line) and HR (purple line). This relationship motivates the great interest that field exercise professionals have in monitoring HR responses during exercise. During a submaximal exercise test, it is possible to estimate the VO2 max using submaximal HR responses.
Measurement of Heart Rate
Heart Rate (HR) during exercise can be measured by palpation, auscultation, ECG, and wearable technology (e.g., heart rate monitor, smartwatches).
As you will practice in this lab, measuring HR by palpation is a free and vital—literally—skill that exercise professionals must master.
HR can be palpated at several sites, including the radial, brachial, carotid, temporal, and femoral arteries. This is relatively easy to do when the subject is at rest but can be challenging during exercise due to extraneous noise. Therefore, the radial, carotid, and temporal sites are preferred during exercise. While the carotid and temporal sites are ideal for self-palpation of the heart rate, the radial site is the most appropriate when monitoring a subject's heart rate. After detecting the pulse in one of the sites shown in the figure below, with a stopwatch, count the number of beats over 6, 10, or 15 s and multiply the number of beats by 10, 6, or 4, respectively, to extrapolate the average number of beats per minute. Assessing HR during longer intervals yields greater accuracy. In the example below, the participant's pulse count measurements were taken within the same time window. Results showed that pulse cont was 5 after a 6-second count, 9 after a 10-second count, and 13 after a 15-second count. When extrapolating these pulse counts to beats per minute (bpm), which is the unit used to report the heart rate, the estimated heart rate were 60 bpm for the 6-second count, 55 bpm after the 10-second count, and 52 bpm after the 15-second count. It is important to note that although measurements were taken within the same time window, HR was slightly different between conditions.
Summary: Despite the increased popularity of heart rate (HR) monitors, endurance-trained adults and habitual exercisers often use pulse rate palpation to monitor exercise intensity periodically. However, due to the rapid recovery of HR following exercise bouts, post-exercise palpation of pulse rates may underestimate exercise HR. To test this hypothesis, we studied 20 young physically active adults performing two sets of exercise for 5 min at 70% and 85% of maximal HR on the treadmill, one with carotid and another with radial pulse count. Post-exercise palpation of pulse rate was lower than the actual HR during exercise, underestimating exercise HR by 20–27 bpm (beats per min). Even when ECG tracings of HR were analyzed immediately after exercise (0–15s), a significant under-estimation of exercise HR (7–9bpm) persisted. Following exercise, the pulse rate obtained by carotid palpation at both intensities and radial palpation at the lower intensity differed from the corresponding HR measured with ECG. In the radial artery trial at the higher exercise intensity, pulse rate following exercise was lower (10bpm) than ECG-derived HR. Arterial stiffness, which is closely associated with arterial baroreflex sensitivity, was not significantly related to the changes in HR with carotid palpation.
For the last 15 years, ACSM's Health & Fitness Journal Links to an external site. editors have circulated an electronic survey to thousands of professionals worldwide to determine health and fitness trends for the following year. This survey guides health and fitness programming efforts for 2021 and beyond. The first survey, conducted in 2006 (for predictions in 2007), introduced a systematic way to forecast health and fitness trends. These surveys have been conducted annually since that time (2–14) using the same methodology. As this is a survey of trends (and not fads), respondents were asked first to make the critical distinction between a "fad" and a "trend."
Wearable technology has ranked number one trend since first introduced on the American College of Sports Nutrition Survey Worldwide Survey of Fitness Trends in 2016. These devices can record heart rate during exercise and throughout the day. Additionally, some of the most advanced smartwatches can monitor variations in time between the heartbeats, namely heart rate variability (HRV). The HRV is a feasible biomarker that gives great insight into the autonomic nervous system, the main controller of body functions. For example, higher HRV correlates with increased vagal tone, which has a cardioprotective role during rest and exercise. At the onset of exercise, vagal withdrawal can be estimated using HRV. Furthermore, smartwatches can be used as a step counter, body temperature measurement, calory expenditure estimation, sitting time and sedentary behavior quantification, sleep time quality, and much more. Innovations include blood pressure and oxygen saturation.
Module Activities
Complete the following activities during Laboratory 7. Click on the Modules below or use the Next button at the bottom of this page to access the content.
- Concept Check for Laboratory 7
- Discussion for Laboratory 7
- Laboratory Activity 7 - Submaximal Exercise Testing
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