Hello Readers :
Exercise and DCS
In 1989, noting the difference between the risk of DCS in the legs between individuals depressurized on the ground and in space on the same depressurization schedule, I proposed that this was the result of exercise-generated nuclei in the lower limbs. This work has sparked a large number of studies where exercise has been a variable in decompression sickness. It has rekindled an interest in micronuclei and the ability to control their concentration in vivo.
Physical Fitness and DCS
The protection afforded by physical fitness has generally been ascribed to the increase in capillary density in tissues. More capillaries allow inert gas to be removed faster from the tissue. (Gas uptake is faster, but this is always a very rapid process.)
There is also the apparent addition of some effect ascribable (in whole or in part) to nitric oxide, a chemical transmitter and mediator produced by the body. (This compound should not be confused with nitrous oxide or laughing gas.)
Exercise 24 hours prior to depressurization appears to be of value with respect to the reduction of DCS in rats and humans. This can even be caused by a single period of exercise in unconditioned rats. It would seem that a boost in physical fitness is not the sole mechanism. Because of the ability of nitric oxide to modify the endothelial cells (lining of capillaries) as well as the current notion to implicate it in everything physiological it was a prime candidate. The addition of an agent that blocks the production of nitric oxide (by inhibiting the enzyme nitric oxide synthase) seems to reduce the number of bubbles generated.
From an analysis of data from another NASA study of a college (Dr KV Kumar), I can also state that exercise 24 hours prior to depress not only reduces bubbles (Doppler bubbles) but also reduces the cases of DCS.
Dr Deco :doctor:
