Exercise & diving, How long?

[Rick Inman]

I asked this question in another thread and it went unanswered, so I thought I'd try it here.
After a strenuous 30-60 minute workout, including both aerobic and anaerobic exercise, how long should a person wait before diving? Then, after a day of diving, how long before doing the workout again?
Look, it I have to give up my new exercise program for diving, I will .

 

[smrtblnddiver]

I was always told to work out after diving, if at all.

But when I was on a vacation in Curacao, one of the men worked out every morning and on my recent trip a woman ran each morning.

But, I'm no doctor.

 

[Saturation]

There are several components to exercise. A lot depends also on the heaviness or vigor of the exercise. Few studies are definitive in the medical literature sense, but there are many many studies suggesting the ff best practice:

Exercise increases N2 elimination, uptake and creates bubble nuclei. Balancing all these factors is key.

The risk of a fit person to DCI in lower than an unfit diver.

A time interval as short as a 3 hours maybe used after strenuous exercise and diving, however, there is still a smaller baseline risk of increasing nucleation. A safer interval is at least 6 hours after exercise, or at best one day. Its estimated the half life of bubble nuclei seeds are ~ 1hour, so 6 half lives reduce bubble seeds 98%, and additional hour reduces the seeds numbers even more. By 12 hours, it down almost 99.99%

Marked exertion, more than 4 METS, within the dive will increase N2 uptake and increase DCI risk. Its best to be as quiescent or 'zen' state during the dive.

During the safety or deco stop, a low level exercise will help offgas, ~ 4 METS , 0.25 knots swimming, or slightly flexing of the extremities.

After a dive, exercise will form nuclei to seed bubbles. Considering half lives again, the same numbers hold, at least 5-6 hours after a dive, and better up to 1 day after a dive. The risk also depends on the amount of N2 or He uptake during the dives, to provide the inert gas to grow the bubble seeds, this gas load is proportionate to depth and time.

Following the PADI RDP table, divers will start at any pressure group and be A group in about 3 hours, then off A group after 6 hours. This thus, lowers the inert gas load to near baseline levels, coincidental with the bubble seed lifespan. Add to this, a further 12 hour buffer for flying after diving, so another day is more than enough wait time.

The light exercise during the safety stop is also valid during the surface interval, or SIT. Slow walks, under 3 mph, by sightseeing on foot will enhance off gassing further. After all, the SIT is actually a form of surface decompression, as we rid ourselves of inert gases without bubbling unduely.



Summary:

Do not exercise one day before and after a dive.

Do not exert yourself at depth.

Do not be at rest during the safety stop.

Do not be at rest during the SIT.

 

[pasley]

...After a strenuous 30-60 minute workout, including both aerobic and anaerobic exercise, how long should a person wait before diving? Then, after a day of diving, how long before doing the workout again?
....

DAN recommend avoiding exercise both before and after diving.
https://www.diversalertnetwork.org/medical/faq/faq.asp?faqid=133

Here is what Divers Alert Network has to say on the subject.:

Diving Medicine FAQs
Exercise & DCS

Q: Is there a problem with working out before or after I go diving? I love to dive, but I'm in training and don't want to miss a workout.

A: Nitrogen absorption and elimination is largely a matter of temperature and circulation. Gas exchange works very well at constant temperature. After diving when body tissues have been loaded with nitrogen, activities such as running, weight lifting or a heavy workload can shake up the bottle of soda so to speak. So exercise after diving requires that you give tissue nitrogen levels time to drop, making bubbling generation less likely in the tissues. You should always start off a dive well rested with muscle that is cooled down and not calling for more oxygen and blood flow.

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, vasoconstrict, and take on less nitrogen. Which means after the dive, we are still cool and not off gassing as a mathematical model may predict. This would appear to favor a diving after exercise procedure. In the 90’s, an altitude study by Mike Powell Ph.D., found that if you waited 2 hours to go to altitude after doing a series of deep knee bends, the number of Doppler bubbles produced at altitude deceased to a baseline level after a two hour wait.

Although there is no definitive answer, a two-hour wait might be considered a minimum waiting guideline for diving after exercise. A more conservative suggestion would be four hours to allow you body to cool down and rest before you add a nitrogen exposure.
Remember to rehydrate after exercise. Although dehydration doesn't cause decompression illness, increased fluid losses decrease you’re off gassing efficiency, so be sure to get plenty of water on dive and exercise days.


I hope the above address your question.

 

[Rick Inman]

Yeah. The posts from Dr. Saturation & Mr. Pasley contained just the info I was looking for. Sounds like the bottom line is that I should wait 6 hours after my morning workout to dive, and then not resume the exercise until the next day. Humm... may make for some early mornings. I broke the rule today and did a dive 2 hours after the workout (easy dive, 57' max. for 42 mins.). However, right now I'm doing my part for DCS prevention: Lazyboy... Laptop...bad TV.
Thanks, guys.

 

[pasley]

... Humm... may make for some early mornings. I broke the rule today and did a dive 2 hours after the workout...). However, right now I'm doing my part for DCS prevention:

I had never really considered exercise before diving until one day this past summer when I had a doctors appointment at 09:00 at the VA. I went out and did my normal run at 6:00 (2 miles). Then I sat in the waiting room from 09:00 until 10:00 (mromal) and when the nurse took my blood pressure with the electronic cuff, well she took it twice; 85/54. She was concerned, but my doctor was unfazed as my normal is 99-101/56-58.

The doc explained that my muscel tissue is using a lot of blood following the exercise for about 4 hours. So anyway, if I am diving I either skip the exercise or wait 5-6 hours after before diving. Then when you asked your question, I went to DAN and looked it up.

Of course follwing exercise you want to ensure your hydrate as well.

 

[Dr Deco]

Dear rick:

This is a frequently asked question and the answer has not been studied specifically for scuba divers. Based on a study referenced below (and mentioned by DAN), the half-life of gas micronuclei is one hour on the average. Some subjects had bubbles whose half-life was as much as two hours. If one waits at least six hours between exercise and diving, I would guess that this would be sufficient.

Strenuous exercise immediately following a dive is potentially harmful. Divers are always in search of the perfect decompression meter or table and such does not exist. Some individuals, if they exercise hard enough will get the “bends” as a recreational diver if they perform strenuous activities with their muscles. However the avoidance of heavy lifting, climbing ladders with full gear, etc, will help reduce this DCS risk considerably.

The duration after diving for exercise is a function of the residual gas in the body. I would suggest waiting six 60-minute halftimes, six hours. This would assure that gas tensions are low enough so that nuclei formation will not be followed by nuclei enlargement.

Dr Deco

References


The effect of exercise and rest duration on the generation of venous gas bubbles at altitude.

Dervay JP, Powell MR, Butler B, Fife CE. Aviat Space Environ Med. 2002 Jan;73(1):22-7.

BACKGROUND: Decompression, as occurs with aviators and astronauts undergoing high altitude operations or with deep-sea divers returning to surface, can cause gas bubbles to form within the organism. Pressure changes to evoke bubble formation in vivo during depressurization are several orders of magnitude less than those required for gas phase formation in vitro in quiescent liquids. Preformed micronuclei acting as "seeds" have been proposed, dating back to the 1940's. These tissue gas micronuclei have been attributed to a minute gas phase located in hydrophobic cavities, surfactant-stabilized microbubbles, or arising from musculoskeletal activity. The lifetimes of these micronuclei have been presumed to be from a few minutes to several weeks.

HYPOTHESIS: The greatest incidence of venous gas emboli (VGE) will be detected by precordial Doppler ultrasound with depressurization immediately following lower extremity exercise, with progressively reduced levels of VGE observed as the interval from exercise to depressurization lengthens.

METHODS: In a blinded cross-over design, 20 individuals (15 men, 5 women) at sea level exercised by performing knee-bend squats (150 knee flexes over 10 min, 235-kcal x h(-1)) either at the beginning, middle, or end of a 2-h chair-rest period without an oxygen prebreathe. Seated subjects were then depressurized to 6.2 psia (6,706 m or 22,000 ft altitude equivalent) for 120 min with no exercise performed at altitude.

RESULTS: Of the 20 subjects with VGE in the pulmonary artery, 10 demonstrated a greater incidence of bubbles with exercise performed just prior to depressurization, compared with decreasing bubble grades and incidence as the interval of rest increased prior to depressurization. No decompression illness was reported.

CONCLUSIONS: There is a significant increase in decompression-induced bubble formation at 6.2 psia when lower extremity exercise is performed just prior to depressurization as compared with longer rest intervals. Analysis indicated that micronuclei half-life is on the order of an hour under these hypobaric conditions.

 

[Rick Inman]

Good stuff, Doc. Thanks!
Reading all this, I can't help but remember doing dives back in the late 70's in Palos Verdes, CA. My brother and I would climb down long treacherous cliffs, then hike around to the next cove, make a dive, then make the LONG hump back up with bags of abs and scallops (this was in the days before the urchins took over). Halfway up the cliff, while praying we wouldn't tumble back down to the rocks below, we would vow never to make this dive again. The hike just wasn't worth it. Of course, next weekend we'd be back. Even made the trek at night once for bugs.
Never got bent, but they were shallow dives and we were in our late teens.
Oh, to be young...
Now it's the treadmill and 6 hour SIs.
Sigh...

 

[dennisg]

Some excellent answers above, here's my view on the topic from the information I have compiled over the years:

All strenuous activities for about four hours prior to scuba diving will increase micronuclei (which are the seeds for decompression illness bubbles), thereby increasing venous gas emboli. Musculoskeletal activity will definitely increase the number of tissue micronuclei. That is an experimental fact. These micronuclei will persist for about two to five hours – again an experimental fact. There are no studies that show clearly what happens to these bubbles when they are compressed by a dive.

It is thought that if one were to put four restful hours between exercise and diving (prior exercise) and six between diving and exercise (post exercise), a diver should be in good shape in terms of absent bubbles. That is probably sufficient for non-decompression dives.

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.

If you send me an email, I'll gladly return you some documents that I have on this topic that I use as classsroom handouts in physiology lectures I present.

Kind regards

DENNIS GUICHARD
NAUI Instructor Trainer
IANTD Technical Instructor
HSE Commercial Offshore Diver Medic
IMCA Saturation Life Support Technician
Red Cross Paramedic (level 4) Primary Emergency Care
ASHI First Aid Instructor
Retired Special Forces member