Some testrides with noninvasive O2 meter

I had a nice opportunity to test a noninvasive O2 meter (http://www.artinis.com/index_oxi.htm). This company makes nice invasive O2 metering systems which can be used for metering O2 values at muscle levels thru the skin. For a test ride I was willing to see would there be any difference between postural and non postural muscles (http://en.wikipedia.org/wiki/Muscle) in isometric work.
I checked values from wrist extensors and back extensors. All the measurements was done in 1 minute. No hyperventilation in breath hold.

Here are the results:

​

1. Normal breathing (wrist extensors)
2. Empty lungs breath hold (wrist extensors)
3. Full lungs breath hold (wrist extensors)
4. Hyperventilation (wrist extensors)
5. Normal breathing (lower back extensors)
6. Empty lungs breath hold (lower back extensors)
7. Full lungs breath hold (lower back extensors)

For me there are least 2 observations: wrist extensors looks like to be little bit more sensitive for hypoxia (non postural muscle) compared to back muscle and the back muscle (postural muscle) O2 levels looks to be little lower compared to wrist extensors.

This gives me pretty nice ideas for further tests as well as some practical use. Would it be quite good idea to use more postural muscles for dynamic apnea and constant weight for example?