Exercise & Diving & DCS

[Arduous]

For those who are interested. I recently wrote D.A.N. and questioned them on the effects of exercise and diving. Specifically how long I needed to wait before or after lifting, before I make a dive. I am involved in heavy training and it is interfering with my diving as I do not dive on training days and I train more days a week then not. The following is the response sent to me via e-mail from D.A.N.


Thanks for the inquiry. In THE PHYSICS, PHYSIOLOGY, THEORY, AND SAFETY OF DECOMPRESSION by Richard D. Vann, B.A., B.S., Ph.D., he addresses the issue of exercise and risks of DCS after diving. Below is an exerpt from the
book.


Exercise

Exercise influences both bubble nucleation and inert gas exchange. The effect of exercise also depends on the phase of the pressure exposure in which the exercise occurs.

Exercise before Pressure Exposure: Bubble Nucleation

Increased bubble formation due to exercise before decompression has been demonstrated in animal studies (Harvey et al., 1944; Whitaker et al., 1945; Evans and Walder, 1969; McDonough and Hemmingsen, 1984a, b; 1985a, b).
Anecdotal reports have linked weight lifting and long distance bicycle racing with increased DCI risk in humans (Vann, 1982b; Nishi et al., 1982). Other forms of pre-exposure exercise have been associated with unusual decompression illness after diving (Hughes and Eckenhoff, 1986) and during
altitude exposure (Piwinski et al., 1986).

Dervay et al. (2001) found that 150 deep knee bends increased the incidence of Doppler detected VGE at 22,000 feet of altitude but that this increase decayed with a halftime of about 60 min as the period between exercise and altitude exposure grew longer. Another study found that heavy weight lifting had no effect on DCS risk with a 24 hr delay between exercise and exposure at 30,000 feet of altitude (Vann et al., 199x).

These studies addressed the effects of anaerobic exercise prior to
animal and human altitude exposures and found evidence for increased DCS risk if the exercise was done immediately or within several hours of decompression but not after a one-day interval. Other studies have investigated the effects of endurance training in rats and pigs and found decreased bubble formation and DCS (Rattner et al., 1979; Broome et al., 1995; Wisløff and Brubakk, 2001). A beneficial effect of physical conditioning was also suggested by the finding that low VGE incidence was
associated with divers who had high maximal oxygen consumptions (Carturan et
al., 1999).

We typically suggest a 24 hour interval before and after diving and heavy
exercise. I hope this information is helpful.

Laurie Gowen, NREMT-B, DMT
DAN Medical Services
Department of Anesthesiology
Duke University Medical Center

Visit DAN's website at: http://www.DiversAlertNetwork.org

 

[MASS-Diver]

Thanks for sharing that report.

I knew not to exerise after diving, but, I frequnetly run or lift during the day even if I have dive that evening or night. Guess I'll have to rethink that.

I guess the effects of exercise (lots of blood to the muscles) are longer lasting than one might think and leave the body less able to off-gas even say 5 hours after running a few miles?

And wow, a 24hr interval before and after exercise - that's a long time - heck, some weeks I would not be able to work out at all.......

 

[DocVikingo]

And, in general, such an approach would seem to be ethically & legally prudent given our incomplete knowledge of so many matters involving dive physiology & medicine.

This appears to be a very extreme example.

I'll be interested in what DrDeco has to say.

Best regards.

DocVikingo

 

[Dr Deco]

Dear Arduous:

Exercise and Nucleation

As the material from DAN indicated, strenuous exercise has a negative effect on diver safety and promotes decompression sickness. In fact, of the causative factors, there is nothing as bad as exercise shortly after a dive. One could take a large group of divers and put them on a safe protocol. You could then break the group down into age, gender, hydration, body temperature, smoking, and exercise level. You would find that strenuous exercise by far would be the determining factor (probably followed by hydration).

As DAN stated, the effect of exercise was found during the Second World War with research on high altitude bombing crews. One explanation was the formation of micronuclei by stress-assisted nucleation, and this idea was championed by EN Harvey.

Exercise and Recreational Diving

We had a question similar to this about two years ago. At that time, this was the plan that I thought to be reasonable.

• Prior to diving, one would wait about five nuclei half-lives (approximately sixty minutes) to yield a predive interval of five hours between lifting and diving. {Dervay JP, Powell MR, Butler B, Fife CE. The effect of exercise and rest duration on the generation of venous gas bubbles at altitude. Aviat Space Environ Med. 2002 Jan;73(1):22-7.}
  
• Following the dive, one should wait approximately five halftimes of the sixty minute tissue; thus we have a post dive interval of five hours.
  
• Exercise, in general, has been shown to mitigate the effects of decompression {Powell, 1991; Wisloff U, Richardson RS, Brubakk AO. NOS inhibition increases bubble formation and reduces survival in sedentary but not exercised rats. J Physiol. 2003 Jan 15;546(Pt 2):577-82; Wisloff U, Brubakk AO. Aerobic endurance training reduces bubble formation and increases survival in rats exposed to hyperbaric pressure. J Physiol. 2001 Dec 1;537(Pt 2):607-11.}

Waiting Period

I would be suspicious of a waiting period of 24 hours. It does not accord with the biophysics of decompression sickness according to my studies.

Dr Deco :doctor:

 

[Arduous]

24 hours does seem excessive, then again I think 12 hours seems a bit excessive. My sense of reason tells me that 5 or 6 hours of off gassing should be sufficient, before attempting a heavy workout. However my sense of uncertainty, leads me to dive only on non-workout days.

 

[Dr Deco]

Dear Arduous:

Waiting Time:wacko:

In the days of yore when I worked in hyperbaric medicine, I would attend in the chamber for two hours at 45 feet in the morning and then the same in the afternoon. Not an especially heavy gas load but nontrivial.

I was in the habit or running into work in the morning and running home in the evening. That was six miles each way (12 miles a day). I did this for seven years without any untoward consequences.=-)

Dr Deco :doctor:

 

[MonkSeal]

Arduous once bubbled...
We typically suggest a 24 hour interval before and after diving and heavy
exercise.

I'll have to find someone to carry my gear before and after dive.