Abstract
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| Cycle Ergometer aka Exercise Bike |
This experiment was about finding subjects VO2 max by doing two criterion tests. One was done on a cycle ergometer and the other on a treadmill. Our hypothesis was that the values reached during these exercises would be peak values and not true maximum VO2 values because the subjects would not fully exert themselves due to fatigue and because they were not specifically trained to these modalities. The participants in this lab were four Merrimack College Students between the ages of 20-21 in AH311L in the year 2006. During these tests the subjects heart rate (bpm) and VO2 (ml/kg/min) were monitored, and systolic and diastolic blood pressure (mmHg) were measured during the cycle ergometer test. The VO2, heart rate, and RER (rating of perceived exertion) were found by having the subjects wear a VO2000 gas exchange face mask which was connected to a computer. Graphs were then made based off of these findings and used to see if either subject had reached a VO2 max. For the cycle ergometer criterion test neither of the subjects reached the maximum heart rate that was said to be around 188 bpm. The VO2 max did not plateau and the RER was not >1.1 (Exercise Physiology Laboratory Manual). These are the indicators of VO2 max, and none of them were met. For the treadmill criterion test although two subjects met a heart rate within 12-15bpm of maximum heart rate, the other criteria was not met. The RER’s were not over 1.1 and the VO2 did not plateau. This shows that the treadmill criterion test also did not allow the subjects to reach a VO2 max. After reviewing this data it is safe to say that neither of these tests allowed for all the subjects to reach a VO2 max value because of fatigue therefore can be called peak values.
Introduction
The determination of maximum oxygen uptake (VO2 max) is a general indicator of cardiorespiratory fitness of an individual (B. Knechtle). VO2 max is the maximal capacity for oxygen consumption by the body during maximal exertion. The more active an individual is will most likely have a higher VO2 max level then a sedentary individual. In a study done with wheel chair athletes, they wanted to test whether an inclinated treadmill or increase in velocity and resistance would produce a valid alternative for getting a VO2 max. Their study shows that the increasing inclination shows an affect on a VO2 max, even though a much better alternative would be to use a hand crank seeing how it would be a more preferred activity (B. Knechtle).
However, the capacity of prolonged exercise is only partly explained by VO2 max. Thus, another index must be used to assess athletes and healthy persons (C. Schneider). This is true when talking about athletes that train almost year round for a specific sport. If one was to assess that athletes VO2 max on a modality that had a similar affect to the sport that they played, the athlete would not exert themselves, it would take a long time if they did. The athlete should be tested on a different modality or do a different test on the athlete, such as “ventilatory thresholds on blood enzyme activities, antioxidant capacity, or lipid peroxidation” (C. Schneider).
The purpose of this study was to see if a subject would reach a true VO2 max value on a cycle ergometer with increased resistance or on a treadmill using the Bruce Stage protocol (ACSM 2005). These exercises did not show true maximum values for all of the subjects tested. This can conclude that these tests were not the best in order to prove our hypothesis with the type of subjects that we had.
Methods
These experiments were designed in order to find subjects VO2 max. The subjects included in this test were four
Merrimack College students, two male and two female, that were in the AH311L lab in the year 2006. They were between the ages 20-21 and had already given their informed consent at an earlier date. Also the subjects had filled out a Health history Questionnaire form and a PAR-Q and a liability release. The requirements were explained to the subjects and they were told to wear comfortable athletic clothing and sneakers.
In the cycle ergometer VO2 max criterion test the subjects had blood pressure, heart rate, and gas exchange monitored throughout the entire test. The subjects were first fitted with a VO2000 gas exchange face mask which was hooked up to a computer. A blood pressure cuff and a heart rate monitor were also fitted to the subjects. The subjects started off with a 2-3 minute warm up with a 0 resistance workload. Then the exercise started by cycling at 50rpm for 3 minutes at a resistance based on the subjects heart rate. The resistance was changed by turning the resistance knob in the positive direction which increased force of friction on the flywheel belt that was being moved by pedaling. After every 3 minutes heart rates, blood pressure, and RPE (rating of perceived exertion) were taken. The VO2 was recorded on the computer because of the gas exchange face mask. Based on the heart rate numbers the next resistance was then set, which was based off of the YMCA protocol (ACSM, 2005). This data was taken and recorded every 3 minutes until the subject was no longer able to continue.
For the Treadmill VO2 max criterion test, subjects were tested by using the Bruce 10% protocol (ACSM 2005). The subjects were again fitted with a VO2000 gas exchange face mask which was hooked up to a computer. A heart monitor was used again and obtaining an RPE, but the blood pressure cuff was not used because it is too hard to get a blood pressure while running on a treadmill. The exercise began at a speed of 1.7 mph at a 10% grade. After every 3 minutes heart rate and RPE were taken and the grade was increased by 2%. The VO2 was recorded on the computer because of the gas exchange face mask that was being worn. The subjects continued this exercise until they could no longer continue.
The data from the subjects were recorded on a sheet and the data acquired from the computer was printed out. For the cycle test, graphs were made for the two subjects in the Tuesday AH311L lab. The graphs consisted of heart rate, VO2, SBP (systolic blood pressure) and DBP (diastolic blood pressure) vs. the Workload. For the treadmill test two graphs were made. One was VO2 vs. Bruce Stage for all four subjects and the second was Heart Rate vs. Bruce Stage for all four subjects. The cycle graphs had best fit lines which told us the R values, but the treadmill graphs did not have these values, it was a line graph.
Results
The results were obtained from the graphs that were made after all the data was recorded. Figures 1 and 2 represent heart rate, VO2, SBP and DBP vs. Workload for a female and male subject that did the cycle ergometer criterion test. The female subject, figure 1, reached a heart rate of 186 bpm, the RER was 1.10 and the VO2 did not plateau at the end or increase by levels of 2.1 ml/kg/min with an increase in workload. This shows that a VO2 max was not reached even though the heart rate was within 12-15 bpm of subjects possible max heart rate (220-age), the RER was not >1.1 and the VO2 did not reach a plateau. The male subject, Figure 2, reached a heart rate of 181 bpm, RER of 1.07 and the VO2 also did not plateau or increase 2.1 ml/kg/min with an increase of workload. This shows that the male subject also did not reach a VO2 max because the heart rate was not within 12-15 bpm of the subjects max heart rate (220-age), the RER was not >1.1 and the VO2 did not plateau.
In this Criterion YMCA Cycle Ergometer Test 2 Merrimack College undergraduates were tested, 1 male and 1 female, between the ages of 20-21 (mean age 20.5). Subjects were hooked up to a VO2000 gas analysis system (MedGraphics, Inc) with face mask run by its computer program (Breeze Suite 6.1B) as well as an EKG chest strap type heart rate monitor and blood pressure cuff. Resting heart rate was taken from the heart rate monitor and blood pressure was measured manually by another classmate. The YMCA multi-stage cycle ergometer protocol was used (ACSM, 2005). After a 2-3 minute warm-up on the 0 resistance setting heart rates were read off from the heart rate monitor to determine the level of resistance to start at for the workload. Workload was increased by even intervals as resistance was increased every 3 minutes with heart rate and blood pressure taken each interval by a fellow student as well as VO2, and HR being recorded by the computer program. Subjects terminated the test due to leg fatigue and did not reach maximal heart rate levels (220-age). Male subject 177, age 21, achieved a heart rate level of 181 BPM with RPE level of 9 and Female subject 182, age 20, achieved a heart rate level of 186 BPM with RPE of level 9 as well. Plowman would decide that these tests did not achieve maximal levels since HR levels did not reach 188 BPM in both subjects, VO2 Max did not plateau at the end or increase by levels of 2.1 ml/kg/min or less and their RER did not become > 1.1. Therefore they do not satisfy the 3 requirements, so they are peak values and not true maximum values. The fact that subjects terminated the experiment due to leg fatigue and not cardiovascular fatigue confirms that these were not maximum values.
For the VO2 max treadmill criterion test two graphs were made. Figure 3 is VO2 vs. Bruce Stage for all four subjects that did this test in the year 2006. Figure 4 represents heart rate vs. Bruce Stage for all four subjects. In figure 3 a female subject number 182 had an RER of 1.16 and a VO2 of 25.6 (ml/kg/min) which did not plateau. Female subject number 180 had an RER of 1.14 and a VO2 of 40.4 (ml/kg/min) which did not plateau. Male subject number 177 had an RER of 1.08 and a VO2 of 57.0 (ml/kg/min) which did not plateau. Male subject number 167 had an RER of 1.08 and a VO2 of 63.2 (ml/kg/min) which also did not plateau. Based on this criterion it can be said that none of the subjects obtained a true VO2 max. In Figure 4 the heart rates reached were subject number 180 was 194 bpm, 182 was 184 bpm, 177 was 186 bpm, and number 167 was 177 bpm. The rest was the same as mentioned above for figure 3. Figure 4 was heart rate vs. Bruce Stage; only one subject reached a true max heart rate, subject number 180 with a heart rate of 194 bpm. The rest of the data also shows that this subject reached an RER of 1.14 which is >1.1, but the VO2 did not plateau so the data did not meet all 3 of the criteria.
Four Merrimack College students, two male and two female, ages 20-21 (mean 20.5) performed a Criterion Treadmill Test using Bruce 10% protocol (ACSM 2005) while wearing a VO2000 gas exchange face- mask. During the experiment, the subjects’ heart rate and V02 were recorded by a computer, connected to the gas exchange mask. The Subjects were asked to walk/run on a treadmill for 4 different stages of inclination and speed. Each stage lasted for 3 minutes and the work increased from stage 1 to stage 4. The subjects were asked to perform the exercise until they could not perform any more. Figure 1 shows the relationship between Stage of work done on the treadmill and the subjects V02. It is concluded that none of the subjects actually reached a V02 max by using the 3 criteria for maximal exertion. The Criteria is having a heart rate 12-15 BPM from maximum heart rate, a VO2 plateau, and having an RER > 1.1. Although the subjects did not reach a V02 max, Figure 1 illustrates a positive relationship between Stage and V02.
Four Merrimack College students, two male and two female, ages 20-21 (mean 20.5) performed a Criterion Treadmill Test using Bruce 10% protocol (ACSM 2005) while wearing a VO2000 gas exchange face- mask. During the experiment, the subject’s heart rate and V02 were recorded by a computer connected to the gas exchange mask. The Subjects were asked to walk/run on a treadmill for 4 different stages of inclination and speed. Each stage lasted for 3 minutes and the work increased from stage 1 to stage 4. The subjects were asked to perform the exercise until they could not perform any more. Figure 2 shows the relationship between stage of work done on the treadmill and the subject’s heart rate. It is concluded that only one the subjects actually reached a max exertion by using the 3 criteria for maximal V02 exertion. The Criteria is having a heart rate 12-15 BPM from maximum heart rate, a VO2 plateau, and having an RER > 1.1. Although the subjects did not reach a max heart rate, Figure 2 illustrates a positive relationship between Grade and heart rate.
Discussion
The hypothesis that that the values reached during these exercises would be peak values and not true maximum VO2 values because the subjects would not fully exert themselves due to fatigue and because they were not specifically trained to these modalities seems to be supported by the results of this experiment. The correct determination of VO2 max requires a maximum degree of exertion (B. Knechtle).
Only one subject seems to have the right criteria to have a true VO2 max. The other subjects did not reach a maximum heart rate, an RER >1.1 or have their VO2 plateau. Since the criterion was not met, it can be said that the other subjects only had peak VO2 values and not true VO2 max values. The results obtained support our hypothesis.
The Cycle ergometer criterion VO2 max test and the Treadmill criterion VO2 max test were different in the way that they affected each subject. The cycle ergometer test could have some possibilities of error based on the equipment and the subjects. The VO2000 gas exchange face mask caused some problems during the exercise. The mask was larger then the subjects faces which caused it to not fit correctly. This in turn might not have given the best results for VO2 because the mask might have been letting air out the sides of the mask, not giving a good reading on the gas exchange. Also the heart rate monitors might not have been placed in the right spot on the subjects or have fallen down, giving an inaccurate reading. Subjects discontinued the test because of leg fatigue and because none of them were trained on this modality.
The treadmill criterion VO2 max test also has some possibilities of error based on the equipment and the subjects. The VO2000 gas exchange face mask was used in this test also and it similar problems with it. The masks were too big for the subjects and caused it to give an inaccurate reading by allowing the air to leak out the sides of the mask. The heart rate monitors also could have been a problem because the impact of running, causing the monitor to slip down and give an inaccurate reading. The subjects also stopped both exercises on account of leg fatigue, so neither of the tests was carried out for the entire length.
These tests were a better indication of whether or not a true VO2 max was met then the Pacer, Questionnaire, and YMCA cycle tests. This can be said because the Pacer test had many sources of error such as not doing the exercise right and heart rate monitor malfunctions. The Questionnaire was based on what the subject had to say about their exercising, many could have lied and calculated a VO2 max that was not true. In the YMCA test it was not an all out effort; some subjects also became too fatigued to reach a VO2 that was close to a maximum value. These tests did not give us accurate VO2 results and the criterion tests gave better and closer values to a VO2 max.
Some ways to possibly improve these tests would be to find masks that would better fit the subjects’ faces in order to give better results. As for the heart rate monitors, there should be a better way to get this since it kept slipping off of the subjects. The exercises also caused the subjects to end the tests early due to fatigue and increase of velocity or inclination. If the exercises weren’t as intense or if the subjects were better trained results might have been more accurate. If the exercise protocol were performed for the fixed time rather than to exhaustion, the protective effects of training would have been observed (C. Schneider).
Works Cited
Biology/ AH Dept. 2006 Exercise Physiology Laboratory Manual Fall, 2006 Merrimack College, Pgs 6.1-7.3
Davis, Shala E. Dwyer Gregory B. 2005 ACSM Health Related Physical Fitness Assessment Manual, Lippincot Williams & Wilkins, Baltimore. Pg 104, 119
B. Knechtle W. Kopfli, 2001. Treadmill Exercise Testing with Increasing Inclination as Exercise Protocol for Wheelchair Athletes, International Medical Society of Paraplegia, pg 633
Claudia Schneider Jaqueline Barp, 2005,
Oxidative Stress After Three Different Intensities of Running, Canadian Society for Exercise Physiology, pg 723-734
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