the temptation to speed-up...

[Apneaddict]

I do play UWH, as well as UWR - it was supposed to be to train for freediving in the cold Canadian winter.

 

[Kars]

1.4 m/s with bifins? Are you an underwater hockey player by any chance?

Aris:
I try to do a long swim, then maybe some sprints or near-sprints. I think gym work (squats, deadlifts, squat-jumps) help here too. Exhale sprints at 80-90% of max speed or repeats of ~50% of your max distance but done at fast speed will help. You don't have to turn it into a CO2 table though (unless you want to). Try to finish your sessions like that and I think it will help. I mostly tend towards the gym work and exhales.

I would like to point out that doing exhale dives and even more so exhale sprint dives are much more risky for BO.

Waiting in static for the body to vascular constrict and then doing a swim may be a bit more safe, though the sensations will be very different from regular diving. So proceed with caution and a capable buddy.

 

[chrismar]

Kars,

Can you please explain why you think exhale sprints are inherently dangerous?

Apneaddict,

I play both too, though I found that my freediving performances noticeably dropped when training hard at UWH. Backing off fitness and sprint work reversed the trend fairly quickly. Just something to think about.

 

[azapa]

not to answer on kars behalf, but Exhale anything with a workload is harder to judge IMHO. Contractions are 'strange' to none at all and extreme hypoxia comes from nowhere.

I had a couple of sambas on training exhale dives, one quite good one, mixing the idea of static holds and eq/flexibility depth training, not good. It was a 3:08 hold at 25m, no idea how, on passive exhale, no contractions that I remember, I could feel the intense hypoxia coming on as I surfaced. Wal and Alfredo know the rest.

 

[Kars]

There is basically not much in the lungs, so all the O2 you got is in the blood. The vascular constriction takes a while to kick in and constrict blood flow to limbs. Before and during that time muscles a working aerobically, consuming much O2. Now people do not have a O2 meter inside that gives plenty of warning before approaching low values. The signals are very subtle and LATE.(tunnelvision, gray vision just coming seconds before samba - BO) The CO2 signals are much more easy to feel. But in this case the CO2 feeling remains more or less the same from the start. Then your working out hard, meaning that your focus is moving fast with power, another dent in detecting the end of the dive because of mental focus on something else.

If for some ugly mad reason I was forced to swim into a BO, I would for sure choose an exhale dive, because it's much more comfortable and the struggle phase feels soft making it easy.

My question to more knowledgeable divers here is, why is diving exhale easier?
I think it maybe due to the body able to absorb the little CO2, from the little O2 used, in the lungs and or some other places. CO2 buffer.

 

[chrismar]

For a blackout, I would hyperventilate and do a slow dynamic. I guess everyone is different, but my dive reflex kicks in HARD after a handful of metres. I reasonably often do delayed starts with exhales; sprinting after the first contraction.

I've never blacked out or had LMC on exhale or passive, but had a half-dozen BOs on inhale. I find it too uncomfortable to push that hard on exhale.

 

[Simos]

Does the vascular constriction kick in because of high CO2 or low O2?

 

[Mullins]

Aside from gas concentration, it might also be mechanical. The lower pressure in the chest (compared to inhale dives) makes it easier for blood to move in that direction.

 

[Simos]

Interesting... any practical ways of making it kick in quicker?

When we do pain walks (empty lung fast walking) I am supposed to get lactic in my legs but I never do, instead I just get very dizzy and have to stop. Others get the burning feeling of lactic - I thought it was a good thing I wasn't getting it but now I'm thinking it's probably a bad thing as my muscles are probably working aerobically...