DCS & Excercise

[scubakat]

Hello Dr. Deco!!

In my recent open water training I was warned about exercising after diving, but was not given a guideline for how long to wait. I weight train or do high intensity interval training six days per week and I am trying to figure out how to keep up with my exercise program and dive 2-3 days per week.

I have also seen a couple of references that alluded to intense exercise prior to diving could increase the risk of DCS.

I have been taking my "day off" from the gym and diving then so that I don't miss any workouts, but I will probably dive 2-3 days per week through the summer.

Granted, diving certainly burns more calories than lounging on the sofa, but it is still not my regular focused workout. What guidelines do you use for exercising before/after diving?

thanks!
kate

 

[Dr Deco]

Dear Kate:

This is an interesting question and it indicates a true interest in physical fitness. Scuba diving is an activity that requires a good level of fitness, but the sport itself does not provide the exercise required to maintain one in good shape. Extra work is required.

We were interested in this aspect of decompression at NASA for several reasons. In space (0-g), the physical activity is much less on the legs than on Earth (1-g). Because of this, the buildup of tissue micronuclei is less and the risk of DCS during Extravehicular Activity, EVA, “spacewalks”) is less. Therefore:

• How long after leaving Earth does one attain the nuclei concentration of Earth? That is, how long does it take of the micronuclei to shrink away and dissolve (because of surface tension)?
• If one performs tests in an altitude chamber on Earth, how long must the test subjects remain seated in order to simulate the effects of weightlessness on the leg?
• If astronauts exercise in space (on a treadmill), how long must they wait before performing EVA?

To determine the answer to these questions, we had test subjects perform deep knee flexes and wait for a varying intervals before depressurization to altitude. [Dervay, J, MR Powell, and CE Fife Effective lifetimes of tissue micronuclei generated by musculoskeletal stress. Aviat. Space and Environ. Med., 68 (Suppl), A12. (1997); Dervay, J, MR Powell BD Butler, and CE Fife. Effective lifetimes of tissue micronuclei generated by musculoskeletal stress. (Aviation, Space and Environmental Medicine, Accepted for publication)]. These intervals were five, 60 and 120 minutes. From measurements with a Doppler bubble detector, it was possible to estimate the lifetime of the nuclei (generated by the knee flexes) responsible for vascular gas bubbles. It was assumed that this would be comparable to the tissue nuclei responsible for “the bends.”

The lifetime of these nuclei was estimated at about four hours. That means for the questions list above, we would wait at least four hours for the effects of exercise to dissipate. We use this waiting time for the altitude test subjects on the ground. They remain seated before and during the test to mimic the effects of null gravity on the legs.

I would surmise that if one were to schedule their exercise activities in the morning and diving in the afternoon, there should not be a problem with this situation. One would not need to take off a whole day as far as exercise is concerned. Remember, however, that the activities post dive should not be strenuous (running, climbing ladders, lifting SCUBA tanks). It is good to move about however, and sleeping or being a couch potato should be avoided. :mean:
_____________
[sp]Dr Deco

 

[scubakat]

Thank you for your reply Dr. Deco!

so... I could resonably work out on saturday morning and dive in the afternoon the same day, then dive sunday morning and skip the workout for that day.

or

Dive saturday AM, skip workout, then workout sunday AM and dive sunday afternoon...

is 12 hours post dive enough time before serious exercise?

and, last but not least...

Could you point me to a reference on the net that explains the relationship of micronuclei to bubble formation & DCS in layman's terms? Sorry to be a dunce!

thank you soooo much! you are a great resource!

-kate

 

[Dr Deco]

Dear scubakat:

I would suspect that if you put four restful hours between exercise and diving and six between diving and exercise, you should be in good shape. That is probably sufficient if you are not performing decompression dives. Most divers do not exceed the 60-minute tissue, and this was the basis for calculation of repetitive table for DSAT (the PADI tables)

Generally speaking, six HALF TIMES is considered the duration necessary for a system to “reset” itself to the “base line”. This is why for example, that 12 hours is given as the “time to fly” after diving. Since the longest compartment for recreational divers is two hours, the twelve-hour rule follows (2 hr X 6 = 12 hours). If one performs many dives or decompression is involved, then the longest compartment can exceed 120 minutes.

A web site that has some diagrams and explains bubble growth can be found at:

http://www.cisatlantic.com/trimix/emaiken/bubble.htm

[sp][sp]P.S. We are trying to get a Dr Deco web site put together to hold explanations for things such as this, but it is not quite finished.

Dr Deco

 

[ScubaJorgen]

Dear Scubakat,

You might have a look at my homepage . I tried to explain bubble models and VPM especially. Do'nt get frightened by the mathematics. The text (in the first part) should explain the principles. Let me know if it is understandable.

Bye

Jorgen

 

[scubakat]

Thanks Jorgen, I am ptting together a presentation on deco theory for my DM class & your home page will be a great help.

thanks!

-k