Running after Diving

[String]

I merely suggested that you seemed to understand that running after diving is a bad idea, yet were seeking information to the contrary.

Define "running". Define "after".

If you can't then the question asked has some validity.

 

[Bubbletrubble]

This April my wife and I will finally be able to get back into the water after a two year hiatus. My family will be spending just less than a week in Marsa Alam on the Red Sea.

However, I'm planning on running a marathon in May and would rather not go an entire week without running. I'm planning on cutting back my mileage to just easy 8 mile days (<72% HRR). I don't know what our dives are going to be yet, but I would be surprised if we are diving deeper than 60-65 feet. My preference is to stay shallow if possible and "just hang out with the pretty fish."

My concern is I know that exercise is a contributing factor to DCS...what are the guidelines here? I wouldn't want to push my odds by running any intense tempo/interval days while diving, but would I be safe to assume the easy runs...combined with fairly mild depths...won't put me over the threshold?

You must read the current literature on the relationship between exercise and DCS. To not do so would be reckless behavior IMHO.

I'm not going to tell you what to do, but I will give you an anecdotal example of what a runner/diver can "get away with."

One of my dive buddies (age: late-30s) has run several marathons in the past. In 2008, our group took a dive trip to Two Harbors, Catalina Island, where we did 3-4 dives a day over a long weekend. Typical profile for the dives was 60-70 fsw max with avg. depth of approx. 30 fsw and total dive time of 60-70 min. We always completed a minimum of a 5 min. safety stop. Some dives, due to the topography, we spent well over 10 min. at safety stop depth. Water temp. was 49°F. Everyone in our dive group was wearing a drysuit with appropriate undergarment for that water temp. I'd characterize our physical activity underwater as low-to-moderate. Over the weekend he did two rather long runs -- the longest of which was 15 miles -- since he was training for an upcoming marathon (Rock and Roll in San Diego). He woke up really early when he did these runs and got some spectacular sunrise shots with his digital camera, by the way. He did not show any signs of DCS at all. He made sure to re-hydrate following each run. He is a very fit individual and an advanced diver who has excellent buoyancy control. His ascent rate never exceeded 30ft/sec., and his ascent from safety stop to the surface was very, very slow.

You are taking a risk by running and diving in the same timeframe. If you insist on continuing your training while in Marsa Alam, be smart about it. Mitigate the risk by minimizing your nitrogen loading, controlling your ascent rate, lengthening your safety stops, and taking slightly longer surface interval. Schedule runs in the early morning if possible to lengthen the duration of the surface interval (since the last dive on the previous day). Re-hydrate adequately following each run. Monitor for signs of DCS and inform everyone in your dive group of the location of the nearest available hyperbaric chamber.

If you are the kind of diver that gets "exhausted" after doing a couple of not-so-strenuous dives, this could be a sign of decompression stress. I'd recommend making changes to your dive profiles. This can be difficult to do for a newer diver who might not have the best buoyancy control.

Hope you find this info helpful...

 

[JanR]

You must read the current literature on the relationship between exercise and DCS. To not do so would be reckless behavior IMHO.
....Hope you find this info helpful...

Bubbletrubble, no actually you suggested what I should have done from the start. I had a slow day today so I took the time to see what the literature says about the subject. (I've only cited/linked a small number of the articles that I've read today.)

From DAN:

“In summary, physical fitness — including both strength and aerobic capacity — is important for divers both for physical safety and decompression safety. Regular exercise training is best scheduled to separate intense exercise and diving. Intense physical training should be avoided 24 hours on either side of diving activity. Any exercise within 24 hours of diving should involve the lowest possible joint forces.”

DAN Divers Alert Network : Juggling Physical Exercise and Diving

Of course, the words “intense physical training” are not defined in the article and the article’s caution on minimizing joint forces is derived from the author’s previous discussion that speaks of “exercise that is aggressive and/ or stimulates substantial joint-loading.” Again, not an activity that is descriptive of a relaxed run.

In the other corner, we have a 2006 study out of the University of Split School of Medicine that applies the question to diving. Here they induced military divers right after diving to exercise up to 85% VO2MAX…roughly equating to 85% of heart rate reserve…generally considered at the low end of a LT-level tempo run and much more “strenuous” than my intentions. Their findings were that post-dive strenuous exercise reduced post-dive gas bubble formation rather than increased bubble formation.HighWire Medline Abstract

A further study in 2008 by the same researchers (although I only had access to the abstract) states

“Our findings show that exercise performed in a timely fashion before diving or during decompression will reduce the number of venous gas bubbles formed. Exercise after diving did not increase the number of bubbles.”

Beneficial Role of Exercise on SCUBA Diving : Exercise and Sport Sciences Reviews

The proposed (maybe adopted by now) guidelines by the Undersea & Hyperbaric Medical Society read “Divers should avoid any strenuous exercise for 4 hours after a dive with significant decompression stress.” The key words here are “strenuous” exercise” and “significant decompression stress.” So if 4 hours is sufficient interval between a stressing dive and strenuous exercise, you should be able to infer that one should be able do recovery-level exercise following easy dive profiles with less of a interval.http://www.uhms.org/portals/0/pdf/Exerciseafterdiving.pdf

So…I’ve pretty much answered my own question and have now made up my mind. I offer the following only as a guideline as to what I’ve determined after today’s research (and speaking to some of my military diver friends over dinner tonight.)

I intend to do the following, now with very few reservations:

1. Dive NITROX. Based upon projected max depth of dives of around 60 feet and my air consumption, I should finish each dive with only about 50% of NDL.
2. Dives planned to be relaxed and well within our capabilities…going to see the pretty fish and blow some bubbles…not to test our limits.
3. Despite what I had previously indicated with String, I’m back to thinking of running in late afternoon/early evening rather early in the morning. (3-4 hours after last dive). This is for several reasons:
a. Quite frankly…not a scientific reason…but I just hate getting up early. I don’t need that stress in the morning.
b. The one thing that I can control is the run…not the dive. Running after the dive allows me to control the stress on my body. A situation during the dive may take that control over the stress on my body away from me.
c. I’m more concerned about dehydration than anything else. If I ran in the morning, I am locked into a time interval between the end of my run and the beginning of that morning’s dive. With all of the other morning factors involved with travelling with a family, my time to hydrate between events is limited. By running after the afternoon dive, I can postpone the run (even cancel) should I not be rehydrated after the dives.
d. Some of the studies I came across talked about the beneficial effects of aerobic exercise up to 20 hours prior to a dive…produced increased protection against DCS. The protective effects were reduced when the exercise was performed closer to the dive. Should the studies be correct, not only would my early evening runs not exasperate DCS from that day’s dive, it could help protect DCS in the next day’s dives.

Additionally, the runs are not a new stress to my system. In fact, they will represent a sharp decrease in my running volume at that point in my training. And last, several studies show that existing cardio-vascular fitness provides a greater protection to DCS than my sedentary counter-parts, further augmenting my risk assessment.

Take it or leave it. But from what I’ve gathered over the last several hours is that much of the previous thoughts of exercise and diving (which originally prompted me to ask the question) seems to be overly conservative.

 

[Bubbletrubble]

@JanR: I think it's great that you've looked at a few of the research abstracts investigating the effects of exercise on DCS stress. When reviewing the literature on a controversial subject such as this, it's important not to cherry-pick only the papers that would seem to say it's OK to run after diving. Although there appears to be disagreement on whether (and how much) pre-dive exercise might be "protective" against DCS stress (using the measure of venous gas emboli, VGE, as a proxy for DCS stress), several studies on the subject seem to support that vigorous post-dive exercise increases VGE. You did cite a study which demonstrates that intense post-dive cycling actually decreases VGE. Pay attention, however, to the kind of exercise that the Croatian group used in its study -- "short, strenuous incremental upright cycle ergometry, up to 85% of maximal oxygen uptake, for about 10 min." Ask yourself how closely your post-dive runs would approximate that experimental methodology and how well your physiology compares to that of well-trained military divers. Also you may want to consider that running is more of a joint-loading activity than seated/upright cycling.

I'm just going to make a few comments regarding your plan to schedule diving and running in the same timeframe:

b. The one thing that I can control is the run…not the dive. Running after the dive allows me to control the stress on my body. A situation during the dive may take that control over the stress on my body away from me.

I'm not sure how relevant this reasoning is. Whether you run before or after diving, you'll be able to modulate the intensity of your running work-out. Moreover, you do have control over how much physical activity you exert underwater. Avoid dive sites where currents are present. Try to kick infrequently. Remain neutral 99% of the time. Slow down.

c. I’m more concerned about dehydration than anything else. If I ran in the morning, I am locked into a time interval between the end of my run and the beginning of that morning’s dive. With all of the other morning factors involved with travelling with a family, my time to hydrate between events is limited. By running after the afternoon dive, I can postpone the run (even cancel) should I not be rehydrated after the dives.

If you wanted to run in the morning and increase your time to re-hydrate, you could just sit out the first dive of the day. You may want to consider sitting out a few dives even if you plan your runs in the afternoon.

d. Some of the studies I came across talked about the beneficial effects of aerobic exercise up to 20 hours prior to a dive…produced increased protection against DCS. The protective effects were reduced when the exercise was performed closer to the dive. Should the studies be correct, not only would my early evening runs not exasperate DCS from that day’s dive, it could help protect DCS in the next day’s dives.

I think this may be a little wishful thinking on your part. Your dive vacation will include repetitive, multi-day diving. This places your running work-outs in the 24 hr interval before and after dives. I'd be more concerned with the possibility that a run might exacerbate DCS stress from previous dives rather than protect against DCS stress on future dives. I have yet to come across a study that looked at VGE assessment in divers who were exercising on the schedule that you propose.

Be conservative. Have fun and be safe out there...

 

[boulderjohn]

I suggest you check out the Ask Dr. Decompression forum on ScubaBoard. You will find that there have been several recent threads related to this topic. I think you will find them helpful.

Here's one now.

Here's another.