Tuesday, March 12, 2013

Results of VO2 Max test

The results more or less tally with what I would expect: my anaerobic threshold is definitely around 178 bpm (this is the point when my breathing takes on a life of its own) and I would expect my aerobic threshold to be higher than it used to be. It's interesting to see that my RQ (Respiratory Quotient) or, what is strictly speaking the RER (Respiratory Exchange Quotient) - the ratio between volume of O2 inhaled and CO2 exhaled - is exactly what one would expect. A RER of 100% means that the body is deriving all its energy from carbohydrate metabolism, a value of 70% means all the energy is coming from metabolism of fat and so a value of 85% equates to half and half, which is what you would expect at the aerobic threshold. When I did this test 5 years ago, however, the RER at maximum effort was 124% and 100% at my aerobic threshold. Some of this could be due to metabolism of proteins but it is more likely to be due to the CO2 being hotter and occupying more volume as a consequence. I believe that this is one of the reasons that RER is not considered to be a reliable measure of metabolism while exercising. (Incidentally, Wikipedia says that animals can have a RER > 100% if they are storing energy in preparation for hibernation!) The RQ, measured in "moles" (quantities of atoms), is a much more accurate guide but is obviously much harder to determine. Anyway, the point is that my organism has obviously adapted to burning more fat over the last 5 years, which would also help explain how I was able to run a Marathon at my aerobic threshold velocity recently but I was a long way off running a Marathon at my then aerobic threshold pace 5 years ago.

Compare with 5 years ago, the most significant difference, of course, is the velocity at which I ran. This means that my Running Economy has improved. That doesn't really tell you anything you didn't know before because, by definition, your Running Economy is how fast you can run per rate of O2 consumption at a particular threshold, so it conveniently encapsulates everything that VO2 Max tests can't tell us. Another thing that has clearly improved is the rate at which my heart recovers after exercise but, more importantly, my aerobic threshold both as a percentage of VO2 Max and as a percentage of maximum heart rate has increased. This means that I am able to perform at closer to my maximum levels while still being "aerobic".

Just as the training recommendations I was given 5 years ago were extremely optimistic (I would say they are more or less right for how I am now) the new recommendations are equally bullish:

It suggests that I do my easy runs at Marathon pace, my long series at the pace at which I do my short series and my short series at 20 kph! Still, the important thing here to focus on are the relative aspects.

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