Wednesday, September 21, 2011

VO2 Max: Falling Short of The Hype-rventilation (full version)


The VO2 max test is considered by many (myself excluded) to be the gold standard human performance test. It has been largely popularized by a Gatorade add campaign that ran in the early 2000’s featuring beautiful female athletes and well branded male athletes performing maximal treadmill tests. Additionally, during Lance Armstrong’s long reign over the peloton it was well documented that Lance had performed a VO2 max test with a score of 86 ml/kg/min. Naturally an extremely high VO2 max became directly associated with elite aerobic performance. This week I will be posting the 4 reasons the VO2 Max Test isn’t all its hyped up to be. Topics I will address include:

1.       It’s difficult to know if you are actually measuring a subjects maximal oxygen consumption
2.       The VO2 max test downplays the importance of biomechanical efficiency
3.       The VO2 max test downplays the importance of having a high lactate threshold
4.       The formulas used to determine caloric expenditure are poorly validated

Max or Submax- That is the question

                When performing a VO2 max test it can be difficult to determine whether or not true, maximal oxygen consumption was attained. Historically VO2 max tests require the subject to run on a treadmill as long as they can and the amount of oxygen consumed in the last minute of the test is considered the VO2 max. This method often yields sub maximal scores. Physiologically there are four ways to determine whether maximal oxygen consumption has been reached.
1.       No increase in oxygen consumption with an increase in workload (plateau)
2.       Obtaining max HR
3.       RER > 1.1
4.       Blood lactate concentration above 8 mM

At least one of these must occur for a VO2 max test to be considered valid. One must be careful in measuring these criteria, particularly maximal heart rate. Simple formulas like (220-age yrs) are inaccurate and should be taken with a grain of salt.

Downplay of Biomechanics

All other things being equal VO2 max may be the greatest indicator of aerobic performance but all things are NEVER equal. Mechanical efficiency is a metric that attempts to quantify the amount of energy that is being used for mechanical work (running on a treadmill) verses energy given off as heat. With the rise in popularity of clinical testing, biomechanical analysis has fallen by the wayside. Athletes who are biomechanically efficient can “make up” for some of their physiological downfalls. Conversely athletes with elite physiological profiles can shoot themselves in the foot with poor biomechanics.

Downplay of Lactate Threshold

Lance Armstrong’s VO2 max data was incredible but that isn’t what set him apart as an elite cyclist. Lance Armstrong’s super power was his unparalleled ability to utilize fat to produce ATP. Lance Armstrong’s lactate transition occurred at 82 ml/kg/min or at 95% of his VO2 max. This allowed Lance to work at 95 percent of maximal output without fatigue or excess lactate accumulation. Lance relied on the human bodies nearly limitless fat stores to produce ATP rather than the extremely taxing glycoltic pathways.
These are my thoughts on maximal testing. Please comment or email me personally if you wish to discuss this topic. All thoughts, opinions and criticism are valued.

               

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