Apnea Walks! Expected diving improvement?

Hello again!

In your previous question, where you first mentioned about dive time, I said I'd throw out some thoughts if you asked in a new topic. I also thought that it would make your question more visible, hence more likely that others would reply with tips & ideas from their own experience.
Well, that's not happened (so far)... -Maybe most of those reading these forums are more interested in the spearing side? Or maybe they generally feel there's enough material already available out there on 'how to freedive better/longer/deeper' etc., so not worth adding more...?

Well, whatever... I'll give a list of key things first, and then expand on them afterwards. The first and last points will be the looong ones, and they are the ones that are more specifically related to your apnea walk question - but I'll also make them rather more general, in order to deal with the wider question of increasing your dive time.

For the other two points (technique & stretches), I think your courses & instructor(s) should help you more directly, so I'm not going to say much for those and I'll get them out of the way first.

So here's the list of things I will cover (but not in this order, bizarrely enough!)

1. primary aim is to increase comfort time (and other 3 points below are intended to help this...)
2. decrease oxygen usage (i.e. increase efficiency) through better technique
3. enhance initial oxygen volume by doing stretching exercises that increase inhale capacity
4. train dive response (MDR) with regular periods of elevated-CO2 and some low-O2

Two other things that can lead to improvements would be cardio and strength training. For most young people in decent shape, and without any specific confounding medical complications, these are not likely to be huge issues. But they can still improve over time through the usual more well-known types of training (running, swimming, gym, weights, etc., alongside sensible nutrition, etc.), so I'm going to leave it up to you to decide what is appropriate concerning those.

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So... here goes with the two short points...

• Technique​

Since you started freediving only a couple of weeks ago, my guess would be that increasing efficiency through better technique could be one of the quickest ways to increase your dive time.

My reply to your previous question also already mentioned the value of watching videos of yourself, as well as the importance of time & practice.

Clearly, I don't have any idea what your technique is like at this point (maybe you've done a lot of swimming in the past? and you have good awareness & control of your body? and you're a natural in the water? etc.), and that means your instructor is in the best position to point out what you can improve - so I'll leave it up to you to deal with that.

• Stretches​

In the list at the start I already implied that doing regular stretching exercises should help, over time, to increase your inhale capacity (hence more oxygen, hence longer dive times). This is because stretching improves your flexibility (diaphragm, intercostal muscles, ribs, etc.), which allows your lungs to expand more when you inhale.

Again, your courses should be teaching you a variety of appropriate stretches for this, so I'll say no more about that aspect of it.

However, I will note that another good reason to do stretches like these is to help avoid lung squeeze. It's important to realise that, if you just keep trying to get deeper & deeper beyond about 25m, then you are likely to fall victim to lung (or trachea) squeeze unless you first spend some time allowing and preparing your body to adapt and get comfortable at each new depth you reach before moving on. -Suffering a squeeze like this is a really great way to bring your freedive progression to a very unwelcome crashing halt!

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There is a lot to say for the other two points, and I've decided it's taking too long to write it all. Also, it would end up very long and tedious to read through all of this reply, so I'm going to split it up in the hope that will make each section easier to digest...

Part two coming soon(/eventually)...!

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Part two...​

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• Increase comfort time​

You mentioned the apnea walk being "pretty tough", so let's talk about what may be a very important point (which is why I put it first in the list)...

I would suggest to usually avoid having specific end targets (max time/distance/depth) as you do your training sessions. Concentrating so much on reaching a goal like that means you could often spend a significant amount of time towards the end of a dive/walk/breathhold feeling very uncomfortable. (I recall you did mention something like that for your dynamic...)

It's not good to be experiencing that regularly, since such regular discomfort often just ends up training your subconscious mind to want to avoid doing it - eventually even starting to fear it! This leads to increased tension (i.e. decreased relaxation) during future training, and at some point it can suddenly become very hard to progress further.

Instead, aim to increase how long you feel comfortable - what I've called your 'comfort time' - and end a walk/breathhold/dynamic fairly soon after passing beyond your 'comfort zone'. It's a much nicer training session if you know you will feel comfortable for nearly all of it, rather than regularly reaching your comfort limit only to find you're still not near the your chosen time/distance and you have to struggle on for quite some time to reach it.

One of the problems that comes from aiming for a specific target during training is that you are going to be different on different days. All sorts of things can influence how well you do - your sleep last night (or lack thereof), recovering from some exercise yesterday, what you ate/drank that morning or the day before, some unknown minor infection you've picked up... all kinds of little things can have an impact on your body in ways that you really won't know much about (unless you keep a very detailed journal!)

Another possible issue with doing target-oriented freedive training (such as an apnea walk for a set time or number of steps) is the potential for blackout - if you happen to be on a 'low' day, and you blackout while walking, then it's not at all fun if you end up falling on a hard surface...

So, rather than always pushing to reach some pre-determined time or distance goal, instead aim to be governed by how you feel, by what your body is telling you. -Find training methods that mean you actually enjoy your sessions!

- Applying this principle to apnea walks (and other types of training)...

In response to your previous question I gave the example of hanging at 10-15m until first contraction, and then start slowly ascending at that point.

Note that the aim here was not to have some pre-determined time for the hang (e.g. 10s or 20s, etc.) - don't worry about each individual hang/dive time. Instead, look for a signal from your body, such as contraction, and use that to determine when to ascend. Over time, though - weeks, months, years as you do such dives - you should find a general increasing trend for the typical time it takes for your body to reach that point (on the 3rd or 4th dive in a session).

Applying this same idea to apnea walks, I'd say pick a level of discomfort that you only want to experience for a short time, and choose that as the point at which you will start counting maybe five or ten more steps until you finish the walk. If you have contractions during an apnea walk then you could use that as your guide to start counting to the end (similar to doing a hang on the line, and starting ascent soon after first contraction).

Also, don't base the different stages of your walk so much on specific timing (e.g. doing this stage for 20secs, then that stage for 20secs, etc.) Instead, try to judge it by how your body feels. You probably can't do the first couple of stages of a walk like that, since you'll not feel any urge to breathe until nearer halfway through - but try to judge at least the halfway point (i.e. where you would turn in the simulated dive) by how you feel about continuing for roughly the same time that you've already taken to get to the halfway point. I'd even suggest you literally turn around when you reach what you feel would be that halfway mark, and walk back to your starting point. If you've got it right you should find that you make it back to your starting point only a few steps/seconds after you start feeling your chosen level of discomfort.

Building awareness of how your body feels during any particular dive/walk/breathhold is very useful, and the more you take notice of that the better you'll get at it.

The same principle applies for doing static breathholds - don't aim to do a max breathhold every time you do a session, but instead finish each hold at some pre-determined 'signal' from your body (maybe end at 10 or 15secs after your first contraction, or maybe end at your 3rd or 4th contraction - just pick some marker, and use that as the signal that you should end soon...)

Again, since all sorts of things affect each individual dive/walk/breathhold session, your 'comfort time' won't have a straightforward increase over consecutive sessions - there will be variations from session to session - but you would hope to see a general upward trend over the weeks and months.

Every so often you can try for a real max time for your static (maybe once a month, when you're feeling good), and again, you'll see variation from one max attempt to the next - but over the months you should see a general upward trend.

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Part three coming soon(/eventually)...!

I feel like I'm way out of my league in the conservation, but I'll mention the blackouts. A pioneer in Southern California spearfishing used to run holding his breath until he passed out, but he did it on the beach. I have no idea whether running until you pass out is an effective training technique, but if you do it, do it on the sand.

Click to expand...

Woah, that's... extreme... -Hope he didn't pass out too close to the sea with the tide coming in!

I suspect you'd have to be extremely dedicated to overcome potential negative (psychological) effects of blacking out like that so often (or maybe the regular hypoxia meant he didn't remember?! ) -But I suspect it'd be hard to find a freedive instructor who would advocate regularly using such a technique.

(And, yes, re-reading my replies, I'm also feeling a little intimidated and embarrassed... hmmm...)

Yes, the concluding thrilling instalment of this epic reply is finally here!
(Well wow, this has ended up feeling more like writing a series of articles rather than a forum reply...
- I really must work to find a way for those thoughts going round my head to come out much more concisely in the future...)

Part three...​

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• Training the MDR​

I expect you learnt about the mammalian dive response on your course (all that fancy bio-babble: bradycardia, peripheral vasoconstriction, blood-shift, spleen contraction...)

One of the effects of extended breathhold is the increase of CO2, and that is one of the triggers for your body to initiate its dive response. If that happens time after time, your body becomes increasingly trained to 'kick-start' the MDR more quickly & intensely whenever it senses your CO2 increasing (i.e. during any breathhold).

Having a better dive response like this will help to increase your dive time.

Of course, one of the other effects of elevated CO2 is that it becomes uncomfortable, leading to tension, so making it harder to relax. That may well reduce any improvement in dive response, which is why I think the previous section (avoiding too much extended discomfort) can be so important during all this - you don't want to train your body to associate breathhold with feeling bad!

Many words have been written about techniques to help train the MDR, so I'm no doubt repeating much that you've already heard, or can search out for yourself - but I'll also try to suggest some ideas that may be a bit less common.


- Tables (and numerous similar training methods)...

You've probably heard about various types of 'tables' that freedivers practice (CO2 tables, O2 tables, etc...) These are intended to help train 'CO2 tolerance' (i.e. high CO2, hypercapnia) and 'hypoxic tolerance' (i.e. low O2).

Such CO2/O2 tables are fine if you enjoy that sort of structured training and you can regularly set aside time to do them - and there are even apps you can download for your phone that will help you. But I think they can potentially just end up being another form of 'forced discomfort until you reach the goal', which runs against what I was saying in the previous section.

However, there are lots of variations of these, both dry and in the pool (as long as you have a trained buddy, of course), which can make them less onerous, and reduce the need for pre-determined time/distance goals, etc., so it's worth searching for info about such things. You can find lots of ideas & discussion for various training techniques in this forum topic: My DYN training log

In the end, though, I suspect the main effect of such methods is simply to strengthen your dive response when you hold your breath - and that's why I've put them in this section.

- Extended hypercapnia...?

Many of the training methods mentioned above give intermittent high CO2 for fairly short bursts - a few seconds at a time, or maybe up to a minute or two. However, I wonder if there's another method (alongside such training) that also helps improve MDR...

The idea is to regularly (3 or 4 times per week?) spend a longer period of time (maybe 15-20mins?) with continuous elevated CO2 - not as high as you would experience towards the end of a strong static or apnea walk, but just high enough to feel some mild discomfort, and kept at that level for a more extended period of time.

At this point I'm diverging into speculation... does regular sustained elevated CO2 like this actually help improve MDR? - I'd like to see more specific research on this, and find out if others have tried it, and how it worked. (Maybe I should put together a question and see if anyone here in the forums is willing to provide some feedback...?)

But I will say one of the useful things I find about this kind of method is that it can often be done while going about other typical things that happen during your day (rather than carving out a chunk of time for a training session) - for example, sitting on the train to work, while reading or watching TV or working on computer, doing the ironing, in bed before falling asleep, while walking to get somewhere, etc., etc...

The core of the method is to slow down breathing enough to cause CO2 build-up (and mild discomfort), and maintain that level for 10-20 mins or so.

I'd split it up into two main types: static and dynamic...

Static:
Slow down breathing to something like one breath per minute, with each breath having four stages: inhale... hold... exhale... hold...
The exact times are not important, so you don't even need to time it exactly, just count it out roughly (and keep that level of mild discomfort towards the end of each breath). But one breath per minute might have about 15secs for all stages (this is often known as 'square breathing'). Or you can tweak it to taste, e.g. increase exhale to ~20s and reduce final hold to ~10s (can be a bit more relaxing to exhale a bit slower).

Dynamic:
While walking (or maybe during some other prolonged mild exercise), count a certain number of steps (maybe 5 or 6?) for each of the four stages of breathing: inhale 5 steps... hold 5 steps... exhale 5 steps... hold 5 steps...
Again, the exact count isn't important - even a slight upward incline, or carrying bags, can make it noticeably harder, so you have to decrease some or all counts to maintain the chosen level of mild discomfort.
Also, it may take a few breaths before you begin to feel the build-up of CO2, so you could start with a higher count to build-up CO2 more quickly at the start, but you'll find you have to reduce it fairly soon so the discomfort remains sustainable.

- Hypoxic training (low O2)...

So far I've mainly talked about high CO2 (hypercapnia), but the MDR also kicks in with low O2 (hypoxia) - and probably even more strongly if you have both together (again, need more research about this...)

TBH, I think it's unusual to be doing breathhold training where you get (even mildly) hypoxic without also being quite hypercapnic, so you're not likely to be working purely on hypoxia tolerance (despite these so-called 'O2 tables'...)

The slow breathing technique I mentioned above can lead to slight hypoxia (spO2 down from the usual ~98% to maybe 90%, possibly even as low as 85% sometimes? -Get a pulse-oximeter and check as you practice it), so I reckon this may be a decent way to go for reduced O2 as well.

(For anyone wondering about the effects of regular low O2 for extended periods, it's potentially not good for brain cells - but at the relatively small drop that I'm suggesting here, and for just a short period of a few mins each time, I can't see it being an issue - there are people with certain medical conditions who will spend hours of their day with O2 reduced at or below such levels... still, it's probably better to only practice these things a handful of times per week!)

There is another well-known technique that can bring down O2 (briefly) by a lot more, and which may (or may not?) be helpful for training MDR - but I won't go into that here.

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• The End (phew...!)​

Once again I've written way more than I intended, and it's gonna take ages for you (and any other poor readers out there) to trawl through it all. (Well done if you did!)

But I hope there's something useful in there somewhere, and I wish you all the best for your next course!