What you thought you knew about VO2 max- Part 2.

[Tyza]

DISCUSSION

The most important finding of this investigation is that a plateau in the VO2 response is not consistently apparent at the limit of tolerable exercise during either protocol, especially for the PSP. Of the eight participants studied in the two protocols, 89% and 63% of participants would have been excluded in the PSP and PIP groups, respectively, as a result of an absence of a VO2 plateau. Thus the requirement for determining VO2max (ie. no increase in VO2 despite a further increase in WR) is not consistently met, despite apparent maximum effort. This finding is consistent with reports from similar studies (15, 17), and is all the more pertinent considering that attainment of a VO2 plateau is the bedrock on which the BASS base the criteria in question.

In the majority of instances a VO2 plateau in either protocol was elicited concurrently with the null attainment of the fixed RER or HR criteria. This disparity in findings suggests that the plateau, RER and HR criteria do not need to be met concurrently to achieve a VO2peak. Moreover, it seems that plateau and RER criteria do not need to elicit the same responses given the similar VO2 responses in different protocols. When considering the applicability of plateau cut-off values, Howley et al. (9) note that considerable variation in the achievement of a plateau can be due to differences in population, protocol and motivation. However, the methodology used in the current investigation has sought to expunge these extraneous variables.

Respiratory exchange ratio. It is pertinent to note that in the present study there were individuals for whom RER did not increase above 1.0 whereas for others it exceeded 1.25, yet these participants reflected relative maximal effort during exercise, in line with previous findings (16). To that end, given that RER is a proven measure of substrate utilization at different exercise intensities (14, 20) and that the two protocols employed in this investigation vary substantially in duration and progressive intensity, it stands to reason that the PSP should reflect a higher RER response than the PIP, as demonstrated herein (P<0.05). These results showed that VO2peak results after exerting ?maximal? effort are similar for both protocols therefore a cut-off RER value of 1.15 does not, and cannot, apply to all (14). Thus, for an investigator to incorporate a larger data set a lower RER criterion value might be used. However, a consequence of this is that it may exclude participants that have not yet reached VO2max, which would weaken the legitimacy of any study and increase possible errors in a progress assessment of any training program or intervention. Conversely, a higher RER cut-off would eliminate a large portion of those who have actually attained a true VO2max. As mentioned above, it is interesting to note that 63% (N=5) of subjects fulfilled the RER criteria in the PSP while only 38% (N=3) fulfilled it in the PIP.
Indeed, if it were the case that VO2 peaks at 1.15 RER then it follows that those for whom RER exceeds 1.15 should reflect a plateau. However, as demonstrated in this study, of the sixteen tests conducted only one subject whose RER exceeded 1.15 elicited a VO2 plateau, thereby further questioning the validity of this criterion value. These findings are in contrast with the early work of Issekutz et al. (10) who demonstrated that RER could be used to predict VO2max.

Heart Rate. Regardless of its validity in the context of this study, it is important to remember that maximal heart rate is extremely difficult to define for any given population (9). Similarly with the argument against RER, individuals in any population (and as shown in the present study) have shown to elicit HRmax values well above the recommended value. Accordingly, the American College of Sport Medicine (1) stipulate that predicted HR max values should not be used as an absolute endpoint in test termination, lest investigators exclude participants who have yet to reach HRmax. Since HR response is proportional to work rate and RPE values (4), it is pertinent that findings in the present study show maximal values for HR that correspond with RPE values for each of the protocols.
The present data have shown that the use of the so-called established BASS criteria can lead to either significant underestimation of VO2max or rejection of a high proportion of participants who may actually have achieved their VO2max. On the basis of these findings on VO2max testing it is recommended that the use of these criteria, to establish VO2max, be abandoned.

The BASS criteria fail further in their inability to consider inter-individual variability. As demonstrated, all of the criteria do not, and cannot, apply to all individuals (and populations) in whole or in part and if they are to be accepted in the scientific community as an absolute truth then they should apply to any and all individuals and populations, thus acknowledging human variability. Howley et al. (9) have proposed methodological ?guidelines? to promote uniformity in testing subjects for VO2max so as to reduce the chances of erroneous measurement, which they claim accounts for the disparate findings in the literature regarding validity of the criteria. However, they fail to see that if that which is being measured (i.e. VO2) has the same end result under different protocols but the secondary parameters are then shown to be different then it can only be a shortcoming of the criteria in describing VO2, and not the difference in protocol. Therefore their basic understanding of the objection to the criteria is incorrect which leaves their proposed solution a nonsolution.

Indeed, the BASS criteria may find a use when considered as a safety guide, values above which may be considered dangerous to high-risk populations, such as myocardial ischemia sufferers. Perhaps research should focus on defining and refining the criteria based on the physiological limitations of these populations such that its application finds a worthy employ in monitoring intervention progress.

While it is not within the scope of this study to examine the mechanisms determining VO2max, results from this investigation suggest that normal healthy subjects become unable to continue to exercise at a point at which exhaustion is intolerable, despite different protocols, as suggested by the consistently attained VO2 shown in Table 2. In addition, it has been argued that, because a muscle mass recruitment reserve exists at rest, the brain is likely to be the principle organ determining when exercise will terminate (12), thereby bringing into question the means by which we measure maximal oxygen uptake. If this is the case then it is a nonstarter to attempt to define physiological parameters to predict a psychologically governed mechanism, thus abrogating the necessity of the BASS criteria altogether.



REFERENCES

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2.BASSETT, D.R., and E.T. HOWLEY. Maximal oxygen uptake: ?classical? versus ?contemporary? viewpoints. Med. Sci. Sports Exerc. 29:591-603, 2000.
3.BISHOP, D., JENKINS, D.G., and L.T. MACKINNON. The effect of stage duration on the calculation of peak VO2 during cycle ergometry. J. Sci. Med. Sport. 1(3):171-178, 1998
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5.BRITISH ASSOCIATION OF SPORT SCIENCES. Position statement on the physiological assessment of the elite competitor, 2nd Ed. Leeds UK, 1988.
6.DOHERTY, D., NOBBS, L., and T.D. NOAKES. Low frequency of the ?plateau phenomenon? during maximal exercise in elite British athletes. Eur. J. Physiol.89: 619-623, 2003.
7.FROELICHER, V.F., BRAMMELL, H., DAVIS, G., NOGUERA, I, STEWART, A., M.C. LANCASTER. A comparison of three maximal treadmill exercise protocols. J. App.Physiol.36: 720?725, 1974.
8.HERMANSEN, L., and B. SALTIN. Oxygen uptake during maximal treadmill and bicycle exercise. J. App. Physio.26: 31-37, 1969.
9.HOWLEY, E.T., BASSETT, D.R., H.G. and WELCH. Criteria for maximal oxygen uptake: review and commentary. Med. Sci. Sports Exerc. 27:1292-01, 1995.
10.ISSEKUTZ, B., BIRKHEAD, N.C., and K. RODAHL. Use of respiratory quotients in assessment of aerobic work capacity. J. App. Physiol. 17:47-50, 1962.
11.NOAKES, T.D. How did A V Hill understand the V02max and the ?plateau phenomenon?? Still no clarity? J. Sports Med. 42:574-580, 2008.
12.NOAKES, T.D. Testing for maximum oxygen consumption has produced a brainless model of human exercise performance. J. Sports Med. 42:551-555, 2008.
13.POLLOCK, M.L., BOHANNON, R.L., and K.H. COOPER. A comparative analysis of four protocols for maximal treadmill stress testing. Am H. J. 2:39-46, 1976.
14.POOLE, D.C., WILKERSON, D.P., and A.M. JONES. Validity of criteria for establishing maximal O2 uptake during ramp exercise tests. Eur. J. Physiol. 102: 403-410, 2008.
15.ROSSITER, H.B., KOWALCHUK, J.M., and B.J. WHIPP. A test to establish maximum 02 uptake despite no plateau in the 02 uptake response to ramp incremental exercise. J. App. Physiol. 100:764-770, 2006.
16.SIDNEY, K.H., and R.J. SHEPHARD. Maximum and sub maximum exercise tests in men and women in the seventh, eighth, and ninth decades of life. J. App. Physiol. 43:280?287, 1977.
17.ST CLAIR GIBSON, A., LAMBERT, M.I., HAWLEY, J.A., BROOMHEAD, S.A., and T.D. NOAKES. Measurement of maximal oxygen uptake from two different laboratory protocols in runners and squash players. Med. Sci. Sports Exerc. 31:1226-1229, 1999.
18.TAYLOR, H.L., BUSKIRK, E., and A. HENSCHEL. Maximal Oxygen Intake as an Objective Measure of Cardio-Respiratory Performance. J. App. Physiol. 8: 73-80, 1955.
19.WASSERMAN, K., HANSEN, J.E., SUE, D.Y., WHIPP, B.J., and R. CASABURI (1994), Principles of exercise testing and interpretation, 2nd ed. Lea and Febiger, London
20.WAGNER, P.D. Determinants of maximal oxygen transport and utilization. Ann. Rev. Physiol. 58:21-50, 1996.
12.NOAKES, T.D. Testing for maximum oxygen consumption has produced a brainless model of human exercise performance. J. Sports Med. 42:551-555, 2008.
13.POLLOCK, M.L., BOHANNON, R.L., and K.H. COOPER. A comparative analysis of four protocols for maximal treadmill stress testing. Am H. J. 2:39-46, 1976.
14.POOLE, D.C., WILKERSON, D.P., and A.M. JONES. Validity of criteria for establishing maximal O2 uptake during ramp exercise tests. Eur. J. Physiol. 102: 403-410, 2008.
15.ROSSITER, H.B., KOWALCHUK, J.M., and B.J. WHIPP. A test to establish maximum 02 uptake despite no plateau in the 02 uptake response to ramp incremental exercise. J. App. Physiol. 100:764-770, 2006.
16.SIDNEY, K.H., and R.J. SHEPHARD. Maximum and sub maximum exercise tests in men and women in the seventh, eighth, and ninth decades of life. J. App. Physiol. 43:280?287, 1977.
17.ST CLAIR GIBSON, A., LAMBERT, M.I., HAWLEY, J.A., BROOMHEAD, S.A., and T.D. NOAKES. Measurement of maximal oxygen uptake from two different laboratory protocols in runners and squash players. Med. Sci. Sports Exerc. 31:1226-1229, 1999.
18.TAYLOR, H.L., BUSKIRK, E., and A. HENSCHEL. Maximal Oxygen Intake as an Objective Measure of Cardio-Respiratory Performance. J. App. Physiol. 8: 73-80, 1955.
19.WASSERMAN, K., HANSEN, J.E., SUE, D.Y., WHIPP, B.J., and R. CASABURI (1994), Principles of exercise testing and interpretation, 2nd ed. Lea and Febiger, London
20.WAGNER, P.D. Determinants of maximal oxygen transport and utilization. Ann. Rev. Physiol. 58:21-50, 1996.

[Eloquent]

I am not digging this copy and paste thing.
If you want to have a decent thread, at least summarize, say your opinion about it, etc.

I do understand this is a sports science post, but again, this is a bodybuilding forum, not a med school panel review thingy.

[hema456]

thank you