Cardio 20 hours before diving reduces venous bubble formation in humans

[Vayu]

I thought I would share this with you guys. I've read about it in rats, but followed up on the research and found this article.

I don't advocate intense exercise during a dive day. This would assume cardiovascular activity the day before.

http://jp.physoc.org/cgi/content/full/555/3/637

This is the first report to indicate that pre-dive exercise may form the basis for a new way of preventing serious decompression sickness.

Any thoughts?

 

[Mr Carcharodon]

Well I have gone for some runs prior to dives since it is hard to schedule training for a marathon and diving at the same time. So far the 14 to 18 mile runs on the same day as the dives have done no harm -- at least as far I as I can tell.

The conventional wisdom is that DCI is driven by inert gas equilibrium. If that is the case it is unclear to me what pre dive exercise has to do with the incidence of DCI. Maybe someone can help me out here. It seem to me that inert gas equilibrium is regained within a few minutes of the conclusion of exercise, at least within fit individuals.

 

[ChillyWaters]

Well I have gone for some runs prior to dives since it is hard to schedule training for a marathon and diving at the same time. So far the 14 to 18 mile runs on the same day as the dives have done no harm -- at least as far I as I can tell.

I'd like to see more posts on intense aerobic activity and diving. I would like to train for another marathon soon too, and would like to understand how to plan it around my diving. From what I've read, I'd be VERY cautious of running an intense 20-miler before diving -- though, obviously its better than after diving.

I generally try to dive on my weekly day off. Of course, that limits how much I can dive. If I run on the same days as diving, I've been cautious, and only run 5-7km at an easy pace.

Sure, aerobic activity 20hours before a dive may reduce bubble formation. But that means you should do your hard run the day BEFORE your dive. However, most studies aren't generally referring to muscle-numbing, fast, 20-mile runs. I'm sure that may change the results too; however, would it be for the better, or for the worse? If unsure, perhaps run the 20-milers at an easy, steady pace.

- ChillyWaters

 

[Vayu]

Well, you guys could try it out some more and report back

Personally, I make sure i'm well rested before a dive and rest well afterwards. I limit weight training to at least 2 days before a dive if not more. I'll continue to do cardio the day before. The only thing I do during a dive day is stretch, carry tanks, and stay hydrated.

Wisløff & Brubakk (2001) have recently shown that a single bout of high-intensity aerobic exercise 20h before the dive protects rats from severe decompression and death by reducing the number of bubbles. Rather than altering nitrogen elimination, exercise may reduce the number of nuclei from which bubbles are formed (Wisløff & Brubakk, 2001).

I'm pretty sure intense exercise during a dive day, before or after, is pushing it. I'd be interested to hear more about it though.

 

[ChillyWaters]

Well, you guys could try it out some more and report back

Actually, I try to stick to common practice: no strenuous exercise 4 hours before, or 8 afters after, a dive. Even then, I only do a shorter, less strenuous stuff.

I limit weight training to at least 2 days before a dive if not more. I'll continue to do cardio the day before.

That's overly cautious!

I'm pretty sure intense exercise during a dive day, before or after, is pushing it. I'd be interested to hear more about it though.

I believe it is common practice to limit strenuous exercise to either 4 hours before, or 8 hours after. Waiting days before diving would mean that divers would generally be VERY out-of-shape.

Here is some info from DAN:
http://www.diversalertnetwork.org/medical/faq/faq.asp?faqid=166

"In one NEDU decompression study, divers actually exercised by running three miles during repetitive-dive surface intervals ... no increase in decompression sickness was seen"

"Exercise before diving may be your best bet. We all enter the water warm and take on nitrogen at a similar rate. Once in the water, we begin to cool, blood vessels constrict, and we take on less nitrogen."

- ChillyWaters

 

[*Floater*]

http://www.direxplorers.com/general-diving-forum/250-fitness-diving.html

 

[MB]

1. Caution is a good, not a bad thing;
2. Workouts that result in micro tears in muscle (such as some forms of weight work) may be an additional, and unnecessary, risk factor;
3. A very real comcern to a serious pre-dive workout involves fluid loss and hydration status. You do not want your tissues to be anything but mushy with juice when diving. Even a minor loss of fluid prior to dives is not a nice thing to do to your body.

 

[ChillyWaters]

1. Caution is a good, not a bad thing;

Not always. For those who dive a lot, and then forgo exercise in the name of caution, it could be a very bad thing. Keeping proper care of your body could put on 20 years on your life...

- ChillyWaters

 

[homo maris]

The article presented deals with exercise 24hrs before diving 18msw. Another paper has studied exercise 2hr before dives to 30msw and came to a similar conclussion.
Aerobic Exercise 2 Hours Before a Dive to 30 msw Decreases Bubble Formation After Decompression
http://www.ingentaconnect.com/searc...8&year_to=2005&database=1&pageSize=20&index=5

Exercise Ending 30 min Pre-Dive Has No Effect on Bubble Formation in the Rat
http://www.ingentaconnect.com/searc...&year_to=2005&database=1&pageSize=20&index=10

Regarding exercise after diving, there were studies by both the US Navy and Duke Univrsity that concluded that exercise after diving increases DCS. Could it be that exercise promotes dehydratation and that dehydratation is the cause of the DCS?

I also found this paper about exercse during decompression interesting:
Exercise effects during diving and decompression on postdive venous gas emboli.
http://www.ingentaconnect.com/conte...00006/art00003;jsessionid=8dbbk35ji9o52.alice

So here is what I do:
Stop exercise 30min before diving and only resume exercise 2hrs after diving. Exercise mildly during my stops and of course drink LOTS of water.

Thoughts?
JL

 

[ChillyWaters]

Regarding exercise after diving, this paper, althrough about rats, may be of interest.
Exercise Ending 30 min Pre-Dive Has No Effect on Bubble Formation in the Rat
http://www.ingentaconnect.com/searc...&year_to=2005&database=1&pageSize=20&index=10

This is regarding pre-dive exercise, not AFTER diving.

I'd still wait several hours after diving before doing much exercise, sitting in a hot-tub, etc.

- ChillyWaters