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Discussion Starter #1
I am in training for a 1/2 marathon, which is quite a challenge given my bmi of 34 and lack of any history of running. I'm currently on week 7 of a 12 week plan (so 1/2 way there:) but I've not run this week due to man flu.
My training plan is calling for longer and longer runs on the weekend but next weekend I am diving. Normally if I am diving I skip a run or make it up in the week. But I'm not going to get a 75min run in this week. I'm seal diving off Lundy on Saturday, max depth 20m, then off to Salcome on Sunday. 35m max no more than 15 mins deco.
Am I increasing my risk of DCI if I go for a run on the Sunday morning?

So far the running is proving a great benefit - I find finning much easier.

Mike
 

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It's a bit difficult to say. The work that suggests a decrease in DCI with exercise before diving is with animals and 18-24 hours before. There is evidence that exercise within a few (say 4 hours) before diving may increase risk. Almost certainly within 4hrs, possibly longer, after will increase risk.
Your window is not very large and given your size you may already be at greater risk than those navy men on whom some of the early work was done.
But far be it for me to discourage exercise and fitness. It gets light at 5.30 get up early and do your run in the week.
Tim Digger
 

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I remember seeing somewhere information suggestiong that a bumpy ride ona rhib reduces the likelyhood of getting a bend. Cant remember where though.

How to replicate that? Dunno. Jump down a big flight of steps one step at a time?
 

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A VS Cash Cow
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I wouldn't worry about it too much, train friday night and then again on monday and don't worry about the runs over the weekend. Its a plan so don't worry about altering a few runs around to make some room for a weekend off. You may find giving your legs a rest will offer more benefits down the line as you will allow the muscles to rest and repair themselves.
 

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All we wanted was a home... Manics
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hi Mike.
Personally I would say (with no medical qualification whatsoever) that it's about risk and likelihood. No-one with sense will tell you do this and you won't get a bend as we all know that people get bends for no good reason.

I would:
1/. Light exercise a good 6hrs before a dive - nothing too heavy.
2/. Think about rehydration and the effect of the exercise.
3/. No exercise for a good 16hrs after a dive

The problem with the above is it isn't a guarantee. How about going on the loop at 100% after the run :D - or take a 3 litre pony on the run with you.... now that WILL kill you!!
 

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You can get access to the complete files from ingentaconnect Home and create a free account.

However, as Tim Digger points out, some of these experiments were done in rats, rather than humans. The venous bubble count experiment was done on military divers.

Regards
 

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Discussion Starter #12
Problem solved - ropes off on Sunday is 0730 so there is no way I'll be arsed getting up early enough to go for a decent run on Sunday morning. I'll try and squeeze an extra one in on Friday or skip one and start back with the plan on Monday.

Cheers for all the pointers - some useful reading for me there. The next weekend that interferes with the traiing schedule is a mix weekend so I'll not be taking any chances there,
 

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All we wanted was a home... Manics
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the second one is interesting as it seems to point to the effect of exercise 2hrs before a dive increasing circulation perhaps opening up the blood vessels and I would imagine a sort of flushing through effect. That said it was stated that the mechanism of what is happening is unclear and in physiology nothing is ever that simple
 

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I'm not aware of any correlation between pre-dive excercise and DCI. However, my concern would be more to do with overdoing it beforehand and so being tired for the dive, possibly leading to over-exersion and the problems that may bring.
 

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I don't suppose the likes of the SBS and US Navy Seals stop excercising prior to a dive. Im fact I imagine there are times that they excercise very hard before diving as a regular scenario. Not comparable I know but would be interesting how they deal with it. Sorry if this is out of turn but I have to confess to not reading the entire thread.
 

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I don't suppose the likes of the SBS and US Navy Seals stop excercising prior to a dive. Im fact I imagine there are times that they excercise very hard before diving as a regular scenario. Not comparable I know but would be interesting how they deal with it. Sorry if this is out of turn but I have to confess to not reading the entire thread.
I think it's less of an issue with them due to high fitness levels. A BMI of 34 is a different matter, though there are cases of well built and fit people with high BMI's.
 

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Discussion Starter #17
I'm not super unfit. I did the 12 minute run test thing that was posted in a YD thread the other day. I lost the thread but managed 1.36 miles in 12 minutes (and then continued at that pace until I'd done my 25 minute run). That's 2188m, or average for the cooper test.
 

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I think it's less of an issue with them due to high fitness levels. A BMI of 34 is a different matter, though there are cases of well built and fit people with high BMI's.
Undersea Hyperbaric Medicine 35:4,

INTRODUCTION: Intravascular bubbles may be detected by Doppler ultrasound in divers following exposure to elevated atmospheric pressures. Doppler signals have been used as an indirect measure of the risk of decompressions sickness (DCS) but few studies have examined factors that might influence levels of detectable bubbles. This study investigated the effects of age, body mass index (BMI) and breathing gas on Doppler bubble levels.

METHODS: Dive data and Doppler results were from of 92 profiles (n=2,216 dives and n=295 male divers) obtained from Navy Experimental Diving Unit (NEDU) experiments (Thalmann, NEDU Reports 1-85 & 8-85). Divers breathed either nitrogen-oxygen (n=708) or helium-oxygen (n=1,508) with a constant oxygen partial pressure of 0.7 atm and performed light exercise at depth with resting decompression in a chamber wet pot. Bubble levels were assessed using the Kisman-Masurel scoring code and converted to the Spencer scale for analysis. Differences between dive profiles were controlled by estimated DCS probabilities calculated with the Navy LEM multigas model (Parker, NEDU Technical Report 92-73). Associations of factors with high bubble grade (HBG = Spencer III-IV versus Spencer 0-II) were assessed by logistic regression with p<0.05 accepted as significant.

RESULTS: There were 861 incidents of HBG (39% of exposures). Helium was more likely to produce HBG (odds ratio [OR]=1.9; 95% confidence interval [CI] 1.6-2.4). When age was dichotomized at the median (27 years; range 20-46) older divers had more HBG (OR=1.5; 95% CI 1.2–1.8) as did divers with BMI scores above the median (24.5 kg/m2; range 20.3-32.4) (OR=2.1 95% CI 1.7–2.5).

CONCLUSIONS: There were significantly more HBG with helium-oxygen than with nitrogen-oxygen, and the HBG incidence increased with age and BMI.
More info on BMI, DCI and age...

Regards
 

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aka Chimp 1 or Mavis...
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I don't suppose the likes of the SBS and US Navy Seals stop excercising prior to a dive. Im fact I imagine there are times that they excercise very hard before diving as a regular scenario. Not comparable I know but would be interesting how they deal with it. Sorry if this is out of turn but I have to confess to not reading the entire thread.
They get around it by pre-breathing 100%....

Pollock NW, Natoli MJ, Gerth WA, Thalmann ED, Vann RD. Risk of decompression sickness during exposure to high cabin altitude after diving. Aviat Space Environ Med 2003; 74:1163-1168.

Background: Post dive altitude exposure increases the risk of decompression sickness (DCS). Certain training and operational situations may require U.S. Special Operations Forces (SOF) personnel to conduct high altitude parachute operations after diving. Problematically, the minimum safe preflight surface intervals (PFSI) between diving and high altitude flying are not known.

Methods: There were 102 healthy, male volunteers (34 ± 10 [mean ± SD] yr of age, 84.5 ± 13.8 kg weight, 26.2 ± 4.2 kg · m−2 BMI) who completed simulated 60 fsw (feet of seawater)/60 min air dives preceding simulated 3-h flights at 25,000 ft to study DCS risk as a function of PFSI. Subjects were dry and at rest throughout. Oxygen was breathed for 30 min before and during flight in accordance with SOF protocols. Subjects were monitored for clinical signs of DCS and for venous gas emboli (VGE) using precordial Doppler ultrasound. DCS incidence was compared with Chi-squared; VGE onset time and time to maximum grade with one-way ANOVA (significance at p < 0.05).

Results: Three cases of DCS occurred in 155 subject-exposures: 1/35 and 0/24 in 2 and 3 h flight-only controls, respectively; 0/23, 1/37, and 1/36 for 24, 18, and 12 h dive-PFSI-flight profiles, respectively. DCS risk did not differ between profiles (χ2 [4]=1.33; crit = 9.49). VGE were observed in 19% of flights. Neither VGE onset time nor time to max grade differed between profiles (82 ± 38 min [p = 0.88] and 100 ± 40 min [p = 0.68], respectively).

Conclusion: Increased DCS risk was not detected as a result of dry, resting 60 fsw/60 min air dives conducted 24-12 h before a resting, 3-h oxygen-breathing 25,000 ft flight (following 30 min oxygen prebreathe). The current SOF-prescribed minimum PFSI of 24 h may be unnecessarily conservative.
 
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