Sunday, January 24, 2010

Using Indirect Measures -- Polar's OwnIndex

From the previous posts it's clear that my goal is to increase overall fitness, improve diet, continue to lose weight, and meet the lipid profile goals associated with my recent calcium heart scan. (LDL cholesterol below 70mg/dl -- now at 77mg/dl; HDL cholesterol > 60mg/dl -- only at 45 but possible if I can tolerate more Niaspan; triglycerides beloww 100mg/dl -- already achieved with Trilipix, hopefully sustainable.)

Fitness is a key, but isn't controlling by itself as I had thought (or hoped)during previous years. For this post I want to focus on fitness and a key indicator of fitness -- O2Max as yielded by Polar's program called "OwnIndex", a fascinating indirect measure of O2Max.

O2Max, of course, is a measure of how much oxygen you can burn at your peak performance level. The more the better. Lance Armstrong has one of the highest measures (he has been described as the "oxygen-burning machine"). The highest scores are in the 90's and are held by Norwegian cross-country skiers.

Interestingly, having among the highest O2Max scores does not guarantee a gold medal in track, but it certainly helps, and when combined with running efficiency, good stride, balance and all of the other good running characteristics, will make you a super competitor. It is regarded as the single best indicator of overall fitness. It is often called the "gold standard" of fitness indicators.

As with many other things, it tends to diminish with age. For my age category, an O2Max in the 40's is considered excellent. But I have not had my oxygen-burning capability directly tested in a lab. That is where they actually hook you up, put you on the treadmill, and measure the amount of oxygen you burn. But I have been tested by the Polar program, which has a .97 corrleation coefficient with direct O2Max testing. And it is done on a bed -- no oxygen mask or treadmill.

In fact, you may have this tool if you have a Polar monitor. It's on the Polar 725 or 810, for example, and probably on most new Polar monitors selling for above $150.

The test consists of wearing the Polar transmitter and setting the monitor on "fitness test". You lie quietly for about 5 minutes. Within that time the monitor reads your heart rate and your heart rate variability (HRM). HRM is an extremely intriguing measure -- the more variability, the greater the indication of fitness. More about this in future posts. You have also entered your age and weight and your current exercise level. On this basis, the Polar gives you a number (mine is currently 41) that is, essentially, the number you would get if you did a direct O2Max test. On the Polar web site, there are tables that intepret your score by age. Mine is shown as "excellent".

These scores are remarkably consistent. If I am a "41" on my 810, my 725 will typically also read "41". They improve slowly over time in accord with an exercise program. I made it to "43" after the last Cycle Oregon. Several years ago it was in the high 30's, so I have made some progress over the years.

According to the Polar literature, movement from an OwnIndex/O2Max score of 40, for example, to 45 would take about 3 months with a more rigorous program.

So I think it is realistic to shoot for an OwnIndex of 45 about 3 months from now, if I am able to ratchet up my weekly exercise level in the right way. If I can keep my weekly mileage within the 100 mile range and do some cross-training -- some running and some hiking, getting up to a 45 by April 24th is realistic.

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