another diving/exercising question

[phoenix09]

I know that you shouldn't exercise right before or right after diving, but I've heard various things on the times you should wait in both cases, and am still confused. I swim and play water polo at school, so to keep up with everything I swim for around an hour most days, at a fairly strenuous pace. I tend to be a bit paranoid about things like DCS, so I wasn't planning on swimming in the couple days before a dive...maybe some light swimming 2 days before, but then stop until a couple days after the dives. I didn't have any problems on my first dives, but considering that I'm about to do a deep dive/multiple dives, I wasn't sure if there was anything else I needed to take into account. Should I stop swimming 1 day before my dives? 2? And how soon afterwards would be safe to start again?

On a related note, I've also been wondering for a while what the deal is with DCS if you're pretty thin...they always mention the risk if you're overweight, but never the opposite, like it is in my case. Thanks.

 

[sky50960]

The best thing to do ( to be as safe as possible ) is no exercise the day you will be diving.

It is said in the litterature that you schould not exercise 6 houres befare and after a dive.


In all cases if you feel tired for any reason( for example too much exercise the day before) DO NOT dive.

 

[DocVikingo]

Hi phoenix09,

I agree. The literature to date is somewhat confusing as regards the exact type and timing of pre and post-dive exercise that may affect the likelihood of DCI.

As such, conservatism appears warranted, although ceasing swimming a couple days before a dive and not resuming it until a couple days after would be considered extreme caution by many experts. A diver who avoids strenuous exercise for 4 hours before and 6 hours following a dive should not be at any meaningfully increased risk of DCI.

There is evidence indicating that reasonable exercise a day before a dive may have a protective effect against the development of DCI, while gentle activity (activity that does not stress joints) immediately following a dive is felt to assist in safe off-gassing.

Remember to stay well hydrated and to monitor any exercise-related aches or pains so that they are not confused with DCI or vice-versa.

This is educational only and does not constitute or imply a doctor-patient relationship. It is not medical advice with you or any other individual and should not be construed as such.

Regards,

DocVikingo

 

[STOGEY]

If it is considered a no,no to excersice aftet diving. Why is it that Navy seals are seen as excersing quite rigorously after they dive?

 

[Scuba]

I'm posting some of the latest published research on this topic. The references were provided by Dr Deco in another thread, but they are more appropriate to the topic of this thread

Keep in mind much remains unknown in regards to DCS, and these are small, very limited studies, therefore - caution is warranted. Nevertheless, the increasing body of evidence appears to point towards the probable usefulness of incorporating some types of exercise at pre-determined times as another tool in decompression management.

Dujic Z, Duplancic D, Marinovic-Terzic I, Bakovic D, Ivancev V, Valic Z, Eterovic D, Petri NM, Wisloff U, Brubakk AO.
Free Full Text Aerobic exercise before diving reduces venous gas bubble formation in humans.
J Physiol. 2004 Mar 16;555(Pt 3):637-42. Epub 2004 Jan 30.
PMID: 14755001 [PubMed - indexed for MEDLINE]

Department of Physiology and Biophysics, University of Split School of Medicine, Split, Croatia.

We have previously shown in a rat model that a single bout of high-intensity aerobic exercise 20 h before a simulated dive reduces bubble formation and after the dive protects from lethal decompression sickness. The present study investigated the importance of these findings in man. Twelve healthy male divers were compressed in a hyperbaric chamber to 280 kPa at a rate of 100 kPa min(-1) breathing air and remaining at pressure for 80 min. The ascent rate was 9 m min(-1) with a 7 min stop at 130 kPa.Each diver underwent two randomly assigned simulated dives, with or without preceding exercise. A single interval exercise performed 24h before the dive consisted of treadmill running at 90% of maximum heart rate for 3 min, followed by exercise at 50% of maximum heart rate for 2 min; this was repeated eight times for a total exercise period of 40 min. Venous gas bubbles were monitored with an ultrasonic scanner every 20 min for80 min after reaching surface pressure. The study demonstrated that a single bout of strenuous exercise 24h before a dive to 18 m of seawater significantly reduced the average number of bubbles in the pulmonary artery from 0.98 to 0.22 bubbles cm(-2)(P=0.006) compared to dives without preceding exercise. The maximum bubble grade was decreased from 3 to 1.5 (P= 0.002) by pre-dive exercise, thereby increasing safety. This is the first report to indicate that pre-dive exercise may form the basis for a new way of preventing serious decompression sickness.

Jankowski LW, Tikuisis P, Nishi RY.
Abstract Exercise effects during diving and decompression on postdive venous gas emboli.
Aviat Space Environ Med. 2004 Jun;75(6):489-95.
PMID: 15198273 [PubMed - indexed for MEDLINE]

Exercise Science Department, Concordia University, McGill University Montreal, Quebec, Canada.

BACKGROUND: Exercise and diving have generally been associated with an increased risk of decompression sickness (DCS), thus accounting for the lack of studies involving exercise during decompression. However, theoretical and observational evidence contrary to this association motivated the present investigation on the effects of moderate, intermittent exercise during diving and/or during decompression on venous gas emboli (VGE) activity following a dive. HYPOTHESIS: VGE observed at both the precordium and subclavian vein sites after diving should be reduced if moderate exercise is performed during decompression vs. remaining inactive. METHODS: In a water-filled hyperbaric chamber, 39 healthy male subjects were compressed to a pressure of 450 kPa (45 msw) for 30 min followed by 55 min of staged decompression. Subjects were either active or inactive at the bottom phase (450 kPa) and/or during the decompression. Activity comprised three 5-min intervals of moderate arm or leg exercise at the bottom and five such intervals during decompression. After decompression, VGE were monitored at the precordium and subclavian vein sites using Doppler detection. Bubble activity scores were converted to various indices and analyzed using non-parametric statistics. RESULTS: VGE activity was invariant as to whether subjects were active or sedentary during the bottom phase of the dive. However, it was significantly lower for all indices examined (p < 0.05) after dives in which exercise was performed during decompression vs. inactive decompression. CONCLUSION: Moderate, intermittent physical activity during decompression decreases VGE activity after diving.

Berge VJ, Jorgensen A, Loset A, Wisloff U, Brubakk AO.
Abstract Exercise ending 30 min pre-dive has no effect on bubble formation in the rat.
Aviat Space Environ Med. 2005 Apr;76(4):326-8.
PMID: 15828630 [PubMed - indexed for MEDLINE]

INTRODUCTION: We have previously shown that exercise performed 20 h before a dive significantly reduces bubble formation in both rats and humans. Furthermore, exercise performed closer to the dive did not prevent bubble formation. HYPOTHESIS: The present study was designed to determine whether exercise 30 min prior to a dive promotes bubble formation. The occurrence of many bubbles is linked to a higher risk of developing decompression sickness. METHODS: A total of 58 Sprague-Dawley rats were randomly divided into a sedentary control group (n = 29) and an exercise group (n = 29).Rats in the exercise group ran on a treadmill for a total of 90 min at variable intensity upto 85-90% of VO2max. Then, 30 min after exercise, one rat from each group rested in a pressure chamber at 700 kPa (7 atm) breathing air, performing a simulated dive. Bottomtime was 45 min; decompression rate was 50 kPa x min(-1) (0.5 atm x min(-1)).Immediately after surfacing (100 kPa, 1 atm), the rats were anesthetized and bubbles were measured discontinuously for the next 60 min. RESULTS: There were no significant differences in survival (p = 0.55), median bubble grade (p = 0.67), survival time (p = 0.53), or the number of rats getting a bubble score > or = 2 (p = 0.79) between the groups. CONCLUSION: The same type and intensity of exercise that reduces bubble formation when performed 20 h prior to a dive neither promotes nor reduces bubble formation if performed 30 min before a dive. The present data indicate that exercise completed 30 min before a dive does not increase the risk of developing decompression sickness in the rat.

Blatteau JE, Gempp E, Galland FM, Pontier JM, Sainty JM, Robinet C.
Aerobic exercise 2 hours before a dive to 30 msw decreases bubble formation after decompression.
Aviat Space Environ Med. 2005 Jul;76(7):666-9.
CEMPP, Toulon Armees, France.

BACKGROUND: A single bout of aerobic exercise 24 h before a dive significantly reduces the formation of circulating venous gas emboli (VGE) on decompression. The purpose of this investigation was to determine the effect of aerobic exercise 2 h before a dive. METHODS: There were 16 trained military divers who were compressed to 30 msw (400 kPa) for 30 min breathing air in a dry hyperbaric chamber at rest, then decompressed at a rate of 10 m x min(-1) with a 9-min stop at 3 msw. Each diver performed two dives dives 3 d apart, one with and one without exercise that consisted of running for 45 min at 60-80% of maximum heart rate (estimated as 220 - age). VGE were graded according to the Spencer scale using a pulsed Doppler detector on the precordium at 30 min (T30) and 60 min (T60) after surfacing. RESULTS: Mean bubble grades at T60 were 1.25 for control dives and 0.44 for dives preceded by exercise, the difference being highly significant. None of the divers showed an increase in venous bubble grade after exercise. CONCLUSION: Like exercise 24 h ahead, 45 min of running 2 h before a dive decreases bubble formation after diving, suggesting a protective effect of aerobic exercise against DCS. The threshold of exercise intensity and duration necessary to change venous circulating bubbles is unknown. Mechanisms underlying the protective effect of exercise remain unclear. Rather than altering the nitrogen elimination rate, exercise may affect the population of gaseous nuclei from which bubbles form.

 

[Scuba]

Dujic Z, Obad A, Palada I, Ivancev V, Valic Z.
Abstract Venous bubble count declines during strenuous exercise after an open sea dive to 30 m.
Aviat Space Environ Med. 2006 Jun;77(6):592-6.
PMID: 16780236 [PubMed - in process]

Department of Physiology, University of Split School of Medicine, Croatia.

INTRODUCTION: The effect of post-dive exercise on bubble formation remains controversial, although the current practice of divers and aviators is to avoid strenuous exercise after diving. Previously, we have shown that exercising 24 h before a dive, or during a decompression stop, significantly reduces bubble formation in man. The objective of this study was to determine whether a short period of strenuous post-dive exercise promotes venous bubble formation. METHODS: Seven male military divers performed an open-sea field dive to a maximum depth of 30 m for 30 min. At maximum depth, subjects performed mild underwater fin swimming, followed by standard decompression. Diving was followed by a post-dive exercise session consisting of short, strenuous incremental upright cycle ergometry, up to 85% of maximal oxygen uptake, for about 10 min. Subjects were monitored for venous gas bubbles in the right heart with an echo-imaging system starting 20 min post-dive while in the supine position, during cycle ergometry in the seated upright position, and immediately after exercise in a supine position. RESULTS: The average number of bubbles was 1.5 +/- 1.4 bubbles x cm(-2) 20 min after diving. Changes in posture from supine to seated upright resulted in significant reduction of bubbles to 0.6 +/- 1.3 bubbles x cm(-2) (p = 0.043), with further reduction to 0.2 +/- 0.3 bubbles x cm(-2) at the end of exercise (p = 0.02). No cases of DCS or intra-pulmonary shunt were observed during or following post-dive exercise. DISCUSSION: These results suggest that post-dive strenuous exercise after a single field dive reduces post-dive gas bubble formation in well-trained military divers. Additional findings are needed for normal sports divers.

 

[Scuba]

Here in Southern California, beach diving involves some sites requiring approximately a 5 min to 10 min level walk with some parts being a short steep inclined path or steps, to reach entry site on pavement, dirt trail and sand surface, plus a return trip after the dive. In addition many divers swim out 100 ft to 100 yards before descending, but not on the way out as one tries to surface near shore. It is also more common to find sites requiring a hike down a steep inclined slope down from atop an aprox. 40 ft to 80 ft bluff, or a walk down many steps 70 to 100?, then across a beach to entry point, with a return after dive trip, with all the gear on, doing some serious huffing and puffing for aprox 10 min to 20 min. Some may take a brief stop along the way to rest before continuing.

Many dives are usually relatively shallow, less than 40 ft to 50 ft. They can also be deeper but usually less than aprox. 130 ft. While the nitrogen loads often do not reach saturation table limits, they can on the deeper dives, at least many probably get close to them since most probably avoid mandatory deco. I would guess many divers ascend using the recreational ascent guidelines of no more than 30 ft p/min and 3 min safety stop at aprox 15 ft, or ascend following the contours of the slope, shallower to the exit point.

I have only seen a mention or two of someone getting bent from beach diving. At the very least, it appears that strenuous exercise before and after the dive for a relatively brief period of time, with after dive nitrogen gas loads of 2/3 or less, usually 1/3 or less, (I'm guessing here as to the average) of leading tissue compartment saturation levels, does not appear to be a very harmful causal factor in DCI. To the contrary, the increasing research into this area increasingly appears to indicate that this type of exercise may actually be of some help, or neutral, or minimally negative.

I present all this here for discussion not as a recommendation, since in a way we are all lab rats in need of better information and communication.

All comments welcomed.

 

[Dr Deco]

Hello Readers:

The “secret” to all of this is that the exercise must be relatively mild. Exercise promotes the formation/growth of nuclei. It also promotes the flow of blood to tissue. These are mutually exclusives events

Tissue blood flow is increased to a point where washout is promoted with just mild activity. Fortunately, this is compatible with minimal formation of nuclei. At the very least, nuclei formation/growth is kept to the degree of activity in which one engages with normal post-dive activity.

Dr Deco :doctor:

The next class in Decompression Physiology for 2006 is September 16 – 17. :1book: http://wrigley.usc.edu/hyperbaric/advdeco.htm

 

[Scuba]

Dr. Deco,

If I may persist.

On another thread you mentioned the advantage of exercise over no exercise during deco had been quantified by NASA in regards to a low pressure environment. Care to advance, with suitable disclaimers, any possible extrapolations which may be useful to divers, based on your extensive knowledge in both fields?.

Dujic Z, Obad A, Palada I, Ivancev V, Valic Z. Abstract Venous bubble count declines during strenuous exercise after an open sea dive to 30 m. Aviat Space Environ Med. 2006 Jun;77(6):592-6. PMID: 16780236 [PubMed - in process]

Diving was followed by a post-dive exercise session consisting of short, strenuous incremental upright cycle ergometry, up to 85% of maximal oxygen uptake, for about 10 min. Subjects were monitored for venous gas bubbles in the right heart with an echo-imaging system starting 20 min post-dive while in the supine position, during cycle ergometry in the seated upright position, and immediately after exercise in a supine position. RESULTS: The average number of bubbles was 1.5 +/- 1.4 bubbles x cm(-2) 20 min after diving. Changes in posture from supine to seated upright resulted in significant reduction of bubbles to 0.6 +/- 1.3 bubbles x cm(-2) (p = 0.043), with further reduction to 0.2 +/- 0.3 bubbles x cm(-2) at the end of exercise (p = 0.02).

Care to elaborate on these findings regarding possible post dive short strenous aerobic exercise benefits?

I'm not quite clear on there being a supine cycling measurement, or an at rest upright measurement, for direct comparison to the alternate. Is there a website where many of these studies full published versions are available to the public?

Changing conditions to performance of mild exercise during deco stop to aid off-gassing, would either the vertical or horizontal position offer an advantage worth considering? I'm aware of the recent thread addressing this question mostly from a lungs gas exchange perspective and body pressure differences. How about from a test results perspective? Any NASA findings related to this issue, naturally as regards a low pressure envrionment?

 

[Dr Deco]

Hello Scuba:


Exercise and Diving

There are only the papers that you already cited for exercise and diving. I would not know how to make a quantitative change from hypobaric [altitude] to hyperbaric [diving] conditions. In the paper by Dujic et al., they exercise to 85% of VO2 max. This is a considerable exercise level. In NASA studies [and at the US Air Force lab], this level of exercise so close to depressurization would have given an increase level of DCS.

It is very possible that short-term aerobic exercise and depressurization are different for hyperbaric and hypobaric conditions since the gas loadings are different. There is not much data on this at the current time, however.

Body Position

I am not aware of any public site with the papers available. Indeed, there are not any comparisons given between bubbles produced and body position. Time will tell.

Body position would not affect gas loads when in the water since the hydrostatic difference is minimal between the legs and heart. Out of the water, recumbent would improve the return of venous blood to the heart from the legs.

Dr Deco :doctor:

The next class in Decompression Physiology for 2006 is September 16 &#8211; 17. :1book: http://wrigley.usc.edu/hyperbaric/advdeco.htm[/url