SWB: Reducing the Risk

[sebastien murat]

Without doing a max dive, but using an O2 sensor and a bucket of icy water, you can do that quite easily. You'd be surprised what you'd learn about cold water and the difference between having the urge to breathe and simply needing to swallow.

Seb

[Fondueset]

This stuff is hugely helpful
A question - when I experience sudden leg fatigue toward the end of a dive - not normal fatigue from kicking, but a sudden burn - is that pretty much an indication of DR kick in? I am not too concerned with pushing the envelope - but safety is definitely primary.
(I'm passing on your mask suggestion to the extremely small freediving contingent here)

[sebastien murat]

Firstly, I'll assume you're not sprinting at the end of the dive because sprinting whether breathing or not => switch to anerobic metabolism = muscle 'burn.'

A couple of things:
- Except in the most extreme cases, no 'burn' at the end of a taxing dive => beware: BO could be around the corner. Exception = increase in Mb stores and anaerobic fitness will delay burn.
- 'burn' = good sign of peripheral vasoconstriction of locomotors even under exercise conditions. Most certainly due to central hypoxia-induced peripheral vasoconstriction, but also apnea/cold-water induced vasoconntriction.
-if you have a poor DR, because of excessively elevated metabolic rate, warm muscles, genetics, training, etc => little to no burn => bad news => risk of BO inversley related to DR, i.e., strong DR => reduced risk of BO.

This means one should opt for strategies that magnify the DR to reduce BO; strategies like minimizing the work rate in the first part of dive, etc.

For sub-max effort dives (i.e., serial dives) a 'burn' is no good.

It all seems complicated but its not. Best way to think of it is like navigating through a mine field: its ok if you know where the mines are! There aren't too many mines.

S

S

[Fondueset]

Thanks!

The burn phenomenon occurs usually during ascent - and definitely not sprinting. I pretty much allways get it if I push the dive - which I rarely do. The only other thing that happens at the end of dives - after surfacing/breathing - is a feeling of heat in the face - like blood is rushing to my head (BP spike probably).

Thanks so much for posting here! I want to optimize safety but still have decent bottom time. I'm really still feeling out my own limitations.

'minefield' - what a soothing metaphor

[dannybuoy]

Hey, what's mines is yours! My mines are your mines. Really, you can have them.

That's why i call you 'sir', sir; huge respect for the way you think. My equations go not much further than hunger => food = hmmm. I'd never have thought of exhaling before a dive, or exposing myself to any form of cold. Now that i've tried, and wimped out on most occasions, i might start deliberating entering your minefield, say in 2012-ish.

[Mullins]

Whether or not you experience leg burn also seems to depend on your swimming speed. I've finished some of my longest (very slow) dynamic swims with little or no leg burn, well past the point at which my legs would have failed completely had I been swimming at 1m/s. I suppose it is a bit different for CW dives though as you're forced to expend a fair amount of energy on the first half of the ascent.

[sebastien murat]

Mullins,

I get in in dynamics also! Sometimes to the point where I can hardly walk after a swim.


Seb

[cebaztian]

I have since taking a course with Murat been trying to switch over to more DR kind of diving.
http://www.freediving.biz/features/muratarticle1.html

Just back from Dahab where I have been doing a couple of CNF to 50 meters. My dives usually involves contractions halfway on the way down. I have learnt to live with this. The pressure makes it somehow endurable (in dynamics I bail out). Now I have sacrificed part of my suit on the altar of the DR-gods.
I have suceeded in getting lactic right after the turn which realy scares the shit out of me - this total fatigue taking every fibre in possesion and feeling of "I am going to BO". I even get lactic in muscles I did not think I have.

I always make it - but it is not pleasant diving "sir Murat" is proposing with is uncahallenged logic.

Next step - get rid of my so much loved mask. I am not looking forward to it. Damn you, SebastiEn ;-)

Sebastian

[sebastien murat]

Freedivers, as opposed to spearfishers, want enjoyable ("it felt easy") dives, all the while realizing their maximum physical potential. Indeed, some in the french and italians schools say: "surfacing with a smile on you face." Just because some world records have been set that way, one certainly should not interpret such as athletes as having realized their true potential....far from it I would argue. My way, there can be no smiling during the dive, only after, otherwise your not where you ought to be.

You can't have it bottom ways...but you can have a little of both!

The damned
S

[amihov]

This is one of the best tread i have read in this forum. It makes sens to remove the mask if you feel that you are on the edge of BO. But isn't this going to affect the balance and peace of the dive. I have been thinking and i haven't tray it yet but it make more sens to take the mask of once when the accent start. If that is going to give you better 02 conservation why wait for the problem when you can just avoid it .
Alex

[GreekDiver]

Sebastien,

What kinda physical training do you recommend for spear fishing other than going a lot? Apnea cycling?

Thanks for the blackout info. Much appreciated.

[sebastien murat]

Amihov,

Sometimes the problem is salient (jumping out at you). Rather it is latent (hidden and dormant...waiting to pounce on you). Indeed, the more you work (exercise) during the first part of a dive (e.g., swimming down) the less your urge to breathe. Furthermore, the faster you ascend, or the larger your (absolute) lung volume, the less your tolerance to hypoxia (low O2). Both of these nfactors, low resistance to hypoxia and reduced urge to breathe increase risk of a BO. Sometimes, divers BO eventhough they surfaced with little, say no, yrge to breathe is what I'm getting at, because of the above.

Seb

[sebastien murat]

Greek Diver,

The best excercise for spearfishing will depend on what your objective is, i.e., the combination on depth, bottom time, dive behavior (sit-and-wait or swim) and surface interval. I can't tell you unless I know these parameters. But, I can tell you, apnea cycling isn't it....sorry. You simply must be in the water...pool ideally.

Seb

[Walrus]

Don't forget trying to improve your swimming/kicking Techique
For example most spearfisherman I've seen dive down on a pretty big angle, if you can learn to descend straight down and streamlined makes a huge difference. One way can be to practise diving on a line, just to get the feeling of what's it's like to be vertical. Also by practising in a pool by counting kicks and checking time per lap you can see the effects of streamlining. My thoughts are most people doing deep or competive type freediving are far more limited by swimming technique rather then their physical training approach. Technique changes can last almost forever rather then physical training will wear off. I've had long periods with no training and still been able to do really big dynamics just from good technique and large lung volume.


Cheers,
Wal

[sebastien murat]

Goes without saying

Seb