by Robh » Wed Sep 02, 2009 5:18 pm
A response from Juerg Kieren :-
Thanks Rob.
Here a few thoughts:
1. VC is a "passive" test, meaning it only tells us how big the bag is in one single breath deep and controlled.
People with something called emphysema have a very wide chest and a surprisingly big VC but a very poor ability ( loss of elasticity ) to
actually use the existing volume properly.
The lungs itself is a "passive " bag. The VC is strongly dependent on the flexibility of the spine in combination with the costovertebral joints.
In people with Morbus Bechterew ( ankylosis spondylitis ) one of the goals is to maintain the costo vertebral mobility as long and as good as possible.
In the late 1890 a Pastor / Dr. Klapp developed a very fascinating mobilization system , which still applies up to this days for people with all kind of spinal misalignments for Rachitis to idiopathic scoliosis.
So if we can motivate people if they age to keep spinal and costovertebral mobility we would see a much smaller decline in VC. In endurance sport . where we breath regular this is much easier to do.
We see in senior cross country skier the smallest drop in VC compared with cyclist , as cycling unfortunately does not do too much for costo vertebral mobility ( MTB better than road ).
The much better idea of a pulmonary function test is not only the VC but as well the VC 1 and VC 6 ( how much air you get out in 1 or 6 sec.
but than much more important is to see, how much of this 6.6 liter you really can use in a FTP intensity of on LBP.
Remember if you have a 6 liter bag and you fill in that bag only 2 liter you have a very low surface tension , which makes it harder to exchange O2 to the red blood cells.
O2 pressure difference.
So really a smaller VC with the same elasticity ratio and the same diaphragm endurance would be better.
There are very interesting measurement done on altitude, where high performance endurance athletes with lot's of muscles and double as big VC like the Sherpas or like a GUY R. Messmer had no chance to move the speed they go an needed O2 much earlier due to the problem of too big VC and too weak endurance ability of the diaphragm.
My son did some studies on the Kilimansharo and he clearly had the most muscles and the biggest VC but the lowest SpO2 from all the people ( all local guys , who walk up and down that mountain the whole time.)
So besides big VC you need a strong "motor" with a great endurance to actually benefit from this situation.
Body builder often have very big VC but are very poor endurance athletes due to exactly the fact , that very often their respiration will be short and often with pressure involved and lot's of mobility in the costo vertebral joints , but no endurance ability in the diaphragm and you often can hear them huff and puff after a set of strength exercises.
Summary . High VC is great , but it is not a free pass for a good respiratory pulmonary work ability .
You need besides the structural size of your lungs ( VC ) as well a great muscular endurance from your inspiratory muscle system.
To be able to breath very intense and long but in the same time you have to avoid ( hyperventialation ) or better dropping of pCO2 as you would get dizzy , you have to know how much air you have to re-breath to keep the pCO2 up, so you can do that over a longer time frame ( 15 min and longer.)
That's where the fundamental difference is between any of this systems like breath easy , power lungs and so on . They all help short term breath increase but don't address the function of the diaphragm , which is open of the classical endurance muscles in our body .
It is the longest working muscle in our body . You start your life with the first breath and you end you life with the last breath.
Old Greek wisdom.