A study of the repeatability of the Bruce Treadmill Protocol in measuring V̇O2max and in estimating V̇O2max through prediction equations
Citation:
Macnamara, Kate Marie, A study of the repeatability of the Bruce Treadmill Protocol in measuring V̇O2max and in estimating V̇O2max through prediction equations, Trinity College Dublin.School of Medicine, 2021Abstract:
Introduction: Maximal oxygen consumption (V̇O2max) is a measure of cardiopulmonary fitness, and a strong indicator of risk of cardiovascular disease (CVD); with a lower V̇O2max increasing a person's risk of CVD. The most reliable method of V̇O2max measurement is via maximal exercise testing with direct analysis of expired air, commonly using the Bruce treadmill protocol. If, due to physical limitations of the participant, or a lack of testing equipment, V̇O2max can be predicted through equations. The first aim of this thesis was to determine the repeatability of the Bruce protocol in measuring V̇O2max. This was achieved through a literature review of previous Bruce protocol repeatability research, and by conducting maximal and submaximal repeatability studies using the Bruce protocol with healthy male adults. The second aim was to determine the reliability of prediction equations used with the Bruce protocol to calculate V̇O2max, again through a literature review of previous research in this area, and then comparing predicted and measured V̇O2max results from the maximal testing study to determine their accuracy. Study 1: The first literature review examined the previous research determining the repeatability of the Bruce protocol in measuring V̇O2max. Eleven studies were deemed eligible for inclusion. All studies concluded that the Bruce protocol was repeatable in measuring V̇O2max, although most findings were based on correlation coefficient analysis, which does not accurately represent agreement between repeated measures. A learning effect was also noted in some of the studies. Study 2: The second literature review analysed previous literature examining different equations used to predict V̇O2max following a Bruce protocol treadmill test. Seven studies were deemed eligible for inclusion. It was found that a number of variables were used to predict V̇O2max, which included exercise variables such as maximal test duration, heart rate, and submaximal V̇O2 extrapolated to maximal heart rate, as well as non-exercise data such as a person's age, body fat or body mass index. The main finding across the research was that the American College of Sports Medicine (ACSM) equations consistently over-predicted V̇O2max and therefore should not be used. Study 3: An initial research study was developed to examine the repeatability of the submaximal Bruce protocol in predicting VV̇O2max in health male adults. The submaximal test was chosen to establish a strict procedure for repeatability testing of the Bruce protocol, in a safe manner. Eighteen participants completed the study, and completed three submaximal Bruce protocol treadmill tests, each a week apart. V̇O2max was predicted using the Fitmate equation, chosen from the results of the previous literature review. Using limits of agreement (LOA) analysis, a wide range in differences between repeated V̇O2max predictions was found (LOA between Test 1 and Test 2: 4.86 to -10.35 ml?kg-1?min-1; LOA between Test 2 and Test 3: 6.67 to -7.96 ml?kg-1?min-1). A learning effect was noted when the mean differences between repeated V̇O2max predictions were examined, as the mean difference between Test 2 and Test 3 was much lower than that between Test 1 and Test 2. Due to the large LOA across all repeated tests, this study concluded that the submaximal Bruce protocol was not repeatable in measuring V̇O2max. Study 4: The final study of this thesis aimed to examine the repeatability of the Bruce maximal treadmill protocol in measuring V̇O2max, as well as to determine the accuracy of several V̇O2max prediction equations, identified through the second literature review. Fifteen healthy male adults completed three repetitions of the maximal Bruce protocol, with a further four participants completing two repetitions. V̇O2max was measured using a metabolic cart. Six prediction equations were used to predict V̇O2max, and these results were compared to the measured V̇;O2max values. It was found that LOA gave a large range for V̇O2max differences between Tests 1 and 2, but a smaller range between the second and third tests. The maximal Bruce protocol was deemed not repeatable from the first to second test, but due to learning effect noted, is likely repeatable at a third test. The most accurate prediction equation was that by Bruce et al.1 for active males ("Bruce 2" equation), while the ACSM equations were found to be unreliable in predicting V̇O2max. Conclusion: The current research has shown that the maximal Bruce protocol is repeatable in measuring V̇O2max but only after a full familiarisation session with the test. The submaximal protocol, with V̇O2max predicted through an equation is not repeatable, based on the current findings. Regarding V̇O2max prediction equations, the ACSM equations should be avoided, and the "Bruce 2" equation appears to provide the most accurate result for healthy male participants.
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https://tcdlocalportal.tcd.ie/pls/EnterApex/f?p=800:71:0::::P71_USERNAME:MACNAMAKDescription:
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Author: Macnamara, Kate Marie
Advisor:
Gormley, JohnPublisher:
Trinity College Dublin. School of Medicine. Discipline of PhysiotherapyType of material:
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