Examining cardiorespiratory fitness testing modalities and protocols.
The first part of this two-part series covered the what, when, where and why of cardiorespiratory fitness testing (September 2004 IDEA Fit-ness Journal, pp. 42–3). Now that you have a little better understanding of the process of choosing an appropriate modality and protocol for testing clients, let’s look more closely at the modalities and protocols available. The most important aspect of the decision process is keeping in mind the client’s health and physical activity history. The bottom line is to match the protocol and the purpose of the cardiorespiratory fitness test to the specific client.
Before choosing a protocol, think carefully about selecting an appropriate modality for your client. Does your client like to run, walk or ride a bike? Does she have balance issues or other musculoskeletal limitations?
The most common modality for cardiorespiratory fitness testing, especially maximal exercise testing, is the treadmill. This modality has some advantages: It requires little skill beyond walking or running, and work rate can be tightly controlled by speed and grade (Howley & Franks 2003). Disadvan-tages include the cost of purchasing a treadmill, nonportability, the difficulty of measuring heart rate and blood pressure during exercise, and inappropriateness for clients with orthopedic limitations (Nieman 2003).
Cycle ergometer testing affords some advantages over treadmill testing. A cycle ergometer is highly portable, more cost-effective and easier to calibrate and maintain than a tread-mill. In addition, heart rate and blood pressure measurements are less difficult to obtain during exercise on the cycle (Howley & Franks 2003). One of the major advantages of using a cycle for testing is that the exercise is non-weight-bearing and less stressful on the lower body, which is a plus for clients who are obese or have orthopedic limitations. A few disadvantages are that work rate on a cycle ergometer is self-paced and not as tightly controlled as on the treadmill—so clients may perform more work than is intended—and localized muscle fatigue in the legs can limit the ability of the client to perform exercise at higher submaximal intensities.
Once you have chosen the modality, find a protocol that fits the purpose of your cardiorespiratory fitness test. There are many different protocols specific to treadmills and cycle ergometers; outlined here are a few of the more common and effective ones for each modality.
Two treadmill protocols that are easy to conduct and are also good predictors of VO2max are the Ebbeling walk and George jogging protocols (Heyward 2002; Nieman 2003). Both are single-stage protocols, meaning there is only one change in workload throughout the test.
The Ebbeling walk begins with a 4-minute warm-up at a speed ranging from 2 to 4.5 miles per hour (mph) at a 0% grade. The speed you and your client choose should produce a brisk and challenging walk. Following the warm-up period, increase the grade to 5% and have your client walk for an additional 4 minutes; record heart rate during the last minute of the test. Use speed (mph), heart rate (HR) in beats per minute (bpm), age and gender (0 for female, 1 for male) to calculate your client’s VO2max with the following equation:
VO2max = 15.1 + 21.8 (speed in mph) – 0.327 (HR) – 0.263 (speed x age) + 0.00504 (HR × age) + 5.48 (gender)
This equation, like the others in this article, simply requires that you plug in numbers and do the math. The numbers that appear in front of all parentheses are constants that were calculated using a statistic called multiple regression. Through this statistic, an equation was created that is representative of all the subjects’ responses (i.e., heart rate, walking speed, age and gender). If the client is male, a 1 is put in parentheses to keep 5.48 in the equation (5.48 x 1). If the client is female, 5.48 is taken out of the equation by multiplying the number by zero.
Here is a sample calculation: Your 40-year-old male client walked on the treadmill at 4 mph and had a heart rate of 130 at the end of the test. What is his VO2max? (Remember order of operations: Do the math in parentheses first!)
VO2max = 15.1 + 21.8 (4 mph) – 0.327 (130 bpm) – 0.263 (4 mph × 40 years old) + 0.00504 (130 bpm × 40 years old) + 5.48 (1)
VO2max = 15.1 + 87.2 – 42.51 – 42.08 + 26.208 + 5.48
Just add and subtract across to get the client’s VO2max in milliliters per kilogram per minute (ml/kg/min): 49.398 ml/kg/ min (or round to 49.4 ml/kg/min).
The George jogging test begins with a challenging jogging speed of between 4.3 and 7.5 mph (women should not exceed 6.5 mph). At 4 minutes and again at 5 minutes, check your client’s heart rate and record. If the two heart rates are within 3 bpm, terminate the test. If they are not, take additional heart rates until they do not differ by more than 3 bpm. (Heart rate should not exceed 180 bpm during the test. If it does, terminate the test.) Use speed, body weight in kilograms (kg BW), heart rate and gender (0 for female, 1 for male) to calculate your client’s VO2max, using the following equation:
VO2max = 54.07 – 0.1938 (BW kg) + 4.47 (speed in mph) – 0.1453 (HR) + 7.062 (gender)
The majority of submaximal cycle ergometer protocols are more complicated than treadmill protocols and take practice to administer effectively. Two very common and accurate methods are the YMCA cycle ergometer protocol and the Astrand-Rhyming cycle protocol.
The YMCA protocol is a multistage protocol that involves a progressive increase in workload based on your client’s heart rate response during exercise. Your client’s VO2max can be calculated by putting the workloads and heart rates for the final two stages of the protocol into the multistage VO2max prediction equation. This equation and a complete description of the protocol can be found in reference textbooks (Heyward 2002; Howley & Franks 2003).
The Astrand-Rhyming protocol is simpler to administer than the YMCA protocol because it involves only a single stage. The goal is to elicit a steady-state heart rate over a 6-minute period. Workload is set during the first minute and maintained throughout the duration of the test. Then VO2max is determined by using a nomogram that utilizes the workload value and steady-state heart rate. A more complete description of the test and nomogram can be found in ACSM’s Guidelines for Exercise Testing and Prescription (ACSM 2000).
By definition, field tests do not involve the use of laboratory modalities (treadmill, bike, step, etc.) to determine cardiorespiratory fitness. Most personal fitness trainers (PFTs) will use an indoor or outdoor track because many field tests require an accurate distance measurement during performance. See “Field Testing Versus Laboratory Testing” on page 36 to see the differences at a glance.
Two of the more common field tests are the Rockport 1-mile walk test and the George 1.5-mile run test. Both of these tests require the client to cover a given distance in the shortest time possible.
The Rockport walk test is perhaps the most widely used because it requires less effort from the client (ACSM 2000). Clients record their weight in kilograms prior to the test, measure their heart rate during the last quarter mile, and record the number of minutes needed to complete the 1-mile walk. You can determine your client’s VO2max from the following equation:
VO2max = 132.853 – 0.1692 (kg BW) – 0.3877 (age) + 6.315 (gender) – 3.2649 (time in min) – 0.1565 (HR)
The George 1.5-mile run requires the client to record his body weight in kilograms and measure the number of minutes needed to complete the total distance (Nieman 2003). You can determine your client’s VO2max from the following equation:
VO2max = 88.02 – 0.1656 (kg BW) – 2.76 (time in min) + 3.716 (gender)
Gender is reported as a 0 for females and a 1 for males for all equations. Nor-mative tables for classifying and interpreting your client’s VO2max can be found in Chapter 4 of ACSM’s Guidelines for Exercise Testing and Prescription (ACSM 2000).
PFTs commonly use a variety of methods to evaluate their clients’ overall fitness. In addition to testing cardiores- piratory fitness, trainers generally test a client’s muscular strength and endurance, body composition and flexibility. Tests are usually done on the same day and very often within a short time period (30 minutes to 1 hour). For this reason, cardiorespiratory fitness tests should be organized in a very specific order, so that no test affects the results of the following tests. The following order is recommended when doing multiple cardiorespiratory fitness testing (ACSM 2000):
1. height, weight, and resting heart rate and blood pressure (if you are testing these)
2. body composition (skinfold, bioelectrical impedance, etc.)
3. cardiorespiratory fitness
4. muscular strength and/or muscular endurance (1-repetition max testing, push-ups and sit-ups)
5. muscular flexibility (sit-and-reach test)
This order provides an accurate baseline for resting heart rate and blood pressure, as well as percent body fat. Body composition testing should never be completed following any type of activity, since a decrease in hydration can greatly influence the accuracy of results. Therefore, cardiorespiratory fitness tests should be done following body composition testing and prior to muscular strength, endurance and flexibility testing. This order allows for a warm-up to enhance the results of the muscular fitness testing while avoiding any effect on body composition results.