Cardiovascular Exercise Before Diving

[padipro1]

OK my fellow instructors, now I have a question to ask and hopefully I can get some conclusive answers. Here is my question: What is the likeliness of predisposing oneself
to DCS or Oxygen Toxicity if intense cardiovascular exercise is done shortly before a dive? Does it increase the chances? It makes no difference? The reason I am asking is that I am a personal fitness trainer (yes I have a real job...), and I have always refrained from doing cardiovascular work on the day/morning of my dive for fear or predisposing myself. Any scientific literature/studies done out there? Any answers would be greatly appreciated.

[disbelief]

There is evidence to suggest that:
- A single bout of heavy exercise at a predetermined time before diving can reduce pre-disposition to DCI.
- Heavy exercise during diving might increase it, though mild exercise during deco may reduce it.
- Exercise post-dive may increase both severity and incidence.

Lippmann & Mitchell summarise the evidence & studies in "Deeper into Diving", Ch 1.

[Rick Murchison]

There is evidence to suggest that:
- A single bout of heavy exercise at a predetermined time before diving can reduce pre-disposition to DCI.

Whoa!
I'm posting before I find the study, ('cause this may be important) which I will cite later, but I distinctly remember that heavy exercise within 45 minutes preceding a dive increased bubbling. If memory serves the "predetermined time" to avoid adverse effects on DCS predisposition was at least two - four hours prior to a dive... and something like eight hours after. Meaning that if you have to have that daily run, you're gonna need to get up early
Rick

[knotical]

ScubaBoard's own Dr Deco has quite a lot to say on this, so searching his posts can be very informative. Here are a couple of fairly recent ones:

Exercise and diving

It appears that predive exercise is less harmful than I originally suspected. Predive exercise forms microbubbles but these are reduced in size by the pressurization of the dive. Exercise at depth and following the dive [on the surface] is harmful with respect to DCS.

Exercise and repetitive diving?

Hello OralDouglas:

Evidence from the last several years seems to indicate that physical activity before a dive is beneficial in reducing DCS risk. Current thinking revolves around some biochemical factor, e.g., nitric oxide, which reduces gas bubble formation/growth during decompression. The reduction in bubbles is real even though the reason is speculative.

Years ago, I cautioned against immediate predive physical activity. Recent studies show this unnecessary. It seems as though any micronuclei generated by musculoskeletal activity are squeezed during the bottom portion of the dive and are of no consequence with respect to later decompression.

Remember that exercise during the decompression (surface) portion must be avoided, as the nuclei generated will expand with the dissolved tissue nitrogen.

Dr Deco

[tkdgodess]

I run before pleasure diving. Run 45 mins at 6 am, diving at 9am. I think if you are physically fit and exercise on a regular regime (as some of us do) then your body is used to it (recovery, metabolic processes etc). I would think if you decided to start running for the first time before diving that might be a problem......

I don't exercise the days I'm a working instructor. It's all shore diving, tank hauling, hill walking, surface swimming, student wrangling.... It's enough exercise. Fitness Trainer IS a real job! (just not at a crappy chain gym...btdt...)

[Rick Murchison]

I run before pleasure diving. Run 45 mins at 6 am, diving at 9am. I think if you are physically fit and exercise on a regular regime (as some of us do) then your body is used to it (recovery, metabolic processes etc). I would think if you decided to start running for the first time before diving that might be a problem......

Two points:
1. It appears that the study I referred to earlier has been superseded by more recent info and that the microbubbles formed during heavy exercise before a dive are inconsequential. They're there, they just aren't harmful.
2. With reference to bubbles & exercise, being in shape has nothing to do with exercise induced microbubble behavior. Indeed, being in good shape may tempt one to exercise sooner, more, and more vigorously than is prudent after diving. Take it easy, especially if deco is involved. Being in good shape has many benefits, but bubbles just don't care
Rick

[tkdgodess]

I run before a dive. Not after. I take it easy after. I lived in a 3 story walk up for 10 years, the futherest parking spot from the door. DH has his "dive sherpa" specialty!

[Kingpatzer]

Our OW dive site is down a flight of about 75 stairs. Before class starts I run up and down those things about 6 or 7 times.

But I'm far more worried about all the bouncing I do between the surface and 30' over a weekend teaching than I am about the effects of the stairs. And I'm not all that worried about the first at all.

[scubamanbo]

not to mention cramping.....is PFT really a job?? hen what is dive instructing??

[padipro1]

Two points:
1. It appears that the study I referred to earlier has been superseded by more recent info and that the microbubbles formed during heavy exercise before a dive are inconsequential. They're there, they just aren't harmful.
2. With reference to bubbles & exercise, being in shape has nothing to do with exercise induced microbubble behavior. Indeed, being in good shape may tempt one to exercise sooner, more, and more vigorously than is prudent after diving. Take it easy, especially if deco is involved. Being in good shape has many benefits, but bubbles just don't care
Rick

Rick. Thanks for the info...