Nitrogen Levels and heart rate

[roughwater]

Hi,

I was just reading somewhere the other day that a persons heart rate is related to how quickly / slowly they take on nitrogen at depth. (That a faster heart rate increases the nitrogen levels delivered to tissue), and that you're better off if you can keep a low heart rate while diving at depth.

I'm far from a guy who understands the human anatomy, but this makes sense to me.

However - I was thinking, if this is true, then would the opposite also be true? (ie, if you were at a safety/deco stop) that the faster your heart rate was, the quicker the nitrogen would leave the body - and if so, wouldn't it be more beneficial to keep moving around (keeping your heart rate up a little more) than resting (sleeping ) while doing deco's.

Everything I've heard about decompression says avoid excersise before, during or after a dive so I guess there's got to be a reason why it doesn't work in reverse. Just wondering if anyone here knows why?

Curious...

Roughwater.

 

[AbyssalPlains]

I have always been interested in this question, too.

 

[TSandM]

Heart rate is only one determinant of cardiac output, and cardiac output (or total tissue perfusion) is what they're talking about. If you are increasing perfusion to all the tissues, it is possible to deliver more nitrogen -- thus the recommendation that dives with significant exertion be treated on the tables as though they were 10 feet deeper than they actually were.

But if I have a resting heart rate of 56, and you have one of 80, it does not mean you are absorbing more nitrogen than I am at a given level of exertion and depth.

There IS some evidence that gentle exercise during decompression aids offgassing.

 

[Dr Deco]

Hello roughwater:

I have been writing about this since SCUBA BOARD began. Yes, do not sit quietly – nor sleep – during the surface off gassing period. You will unload tissue nitrogen slower than the surface interval tables indicate.

Heart rate is one indicator of tissue blood flow. It is a better indicator at higher heart rates than slow one. We are all aware that heart rate can be moderately high in seated individuals if they are tense or nervous.

More import is the local blood perfusion. This is primarily determined by activity of that muscle group. Thus moving the arms while seated will increase blood flow in the arms but not evoke that much of an increase in resting legs.

Dr Deco :doctor:

 

[roughwater]

Hi Guys,

Thanks for your replies - looks like I'll have to look at doing a bit of swimming around on those longer dives when I want to have a greater safety margin.

Cheers