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Improving my SAC rate

Discussion in 'Dive into Fitness' started by bvbellomo, Dec 27, 2019.



    # of Dives: 5,000 - ∞
    Location: Taiwan
    Pretty close....

  2. EireDiver606

    EireDiver606 DIR Practitioner

    Don't over complicate things.

    Get good training - enable you to be more competent, safer, more comfortable.

    Just dive.

    Your SCR will get better.
    BLACKCRUSADER likes this.
  3. scubadada

    scubadada Diver Staff Member ScubaBoard Supporter

    # of Dives: 1,000 - 2,499
    Location: Philadelphia and Boynton Beach
    So...your original example had a low RMV of 7.86 ltr/min or 0.28 cu ft/min.

    My confusion arose when you said you thought your SAC was 8.5. I use SAC as a measurement of pressure over time, psi/min or bar/min. This is cylinder dependent. I use RMV as a measurement of volume over time, cu ft/min or ltr/min. This is cylinder independent.

    This topic has been discussed many times on SB. The two terms are used interchangeably by many discussants and in dive download software. This leads to the confusion often seen in discussions. In my example, in post #52, my download app lists both SAC (psi/min) and RMV (cu ft/min). In your example, post #53, your app lists SAC, which I would call RMV, in l/min.

    Your best dive, with a RMV of 7.18 l/min or 0.25 cu ft/min, demonstrates impressively low gas consumption
  4. johndiver999

    johndiver999 Manta Ray

    # of Dives: 500 - 999
    Location: Gainesville FL
    I agree, there is no universally accepted terminology. A long time ago sac was cu-ft/min, but gradually, terminology has been evolving.

    If people are careful enough to express the units of their "rate" the potential for confusion (or ambiguity) is drastically reduced.
    NothingClever and scubadada like this.
  5. tarponchik

    tarponchik Loggerhead Turtle

    # of Dives: 500 - 999
    Location: USA
    I don't know about hypercapnia. I mean, I do know that it happens, but I never felt any symptoms, though as a diver I am rather reckless. I suppose, though CO2 chemistry is somewhat complicated, most excessive CO2 is blown away during safety stop, same way as N2. Also, people probably can adjust to hypercapnia. I know folks who trained themselves to do shallow breathing, for example.

    As for the aerobics, like I said previously, by running marathons you train yourself to consume more O2, not less. So no relation with SAC here.


    # of Dives: 5,000 - ∞
    Location: Taiwan
    Thanks. If you look at the dive log for that dive you can see it's a fairly shallow dive. Just touched 20m but most of it around 12m or less. I do not mind to dive with OW divers who are just on vacation doing their 10 dives a year....

    That dive was the 25th and last dive of one my 9 day back to back diving days vacations.
    OK nine days of diving without a day off. This is often how I take my vacations.

    Well even I was shocked to tell you the truth. The DM guide was shocked and other divers who had not dived with me before asked me about my air. I just showed them 140 bar remaining. They are like wtf? How is this possible. I replied I am a mutant and have secret gills in my neck. There were chasing turtles and anything else that moved.

    I am diving in the calmest of conditions with the most minimal of effort on these dives. I still do dives where a whole dive is swum against the current. Next time I do one I will post the dive details and SAC rate. I need a good workout now and then underwater. Going to also do a few really fast drift dives in Bali this month so will log those as well. People reading my posts also need to understand I started with Padi OW, then went to BSAC Sports Diving in 1986 and was in a BSAC dive club run by commercial diving professionals. So the training we had might have included things not just from BSAC. There was mandatory twice a week classes and pool training and everything was reviewed again and again for years as you progress to Dive Leader. Nothing like this ever happens in PADI once certified you never retrain. Sports diving is nothing like PADI diving and was considered to be inherently dangerous as everything was done on air and we didn't have dive computers back then. Bring your tables and writing boards to do calculations underwater. Not easy. Some of those dives were really not fun at all.

    So I have gone from planning all dives for multi deco stops with BSAC sports diving to just doing recreational diving in the last decade.

    In 36 years of diving the only incident I have had was a regular BSAC Sports Leader diving buddy had the tie on his mouthpiece break and when he exhaled his regulator came out and when he inhaled, well a wee bit of drama when he inhaled some water. I don't want to explain it all as we were on a deep dive but we got it under control and I had to stop him from hyperventilating. How to do that? Get him to allow me to place my hand over his hand holding his reg and remove from mouth.

    Never had any other type of incident except a coral tattoo or two.


    # of Dives: 5,000 - ∞
    Location: Taiwan

    Good thing with the Perdix is that it will show N2 levels on the dive. How accurate that is depends on the settings as well. I used to run cross country a long long time ago so no idea if that also helped out for my later on if life years? I could just get into a running pace and stick to that. Same when I dive into currents I get into a swimming technique at a set pace and stick to that, or slow down when others struggle. A lot of people are surprised for how long I can just keep on going into a current without getting overly exerted or tired for someone of my size.
  8. Kay Dee

    Kay Dee Barracuda

    # of Dives: I'm a Fish!
    Location: Here, there, and everywhere
    Getting back to the original question of how to lower your ('your' as in almost anybody's) SAC rate / control your breathing rate; below is a simple breathing exercise – variations of which have been practiced by some folks down through the ages - that has helped some people dramatically lower their SAC.

    DISCLAIMER #1. I am not a medico / yoga instructor, etc, etc, etc; just a rather experienced diver with some long term experience in knowing ‘what works, works!’. However, it should go without saying also that you should feel free to reject the following advice out of hand.

    DISCLAIMER #2. This exercise is for practice ON LAND ONLY, NOT / NEVER underwater (and this ‘type’ of breathing IS NOT / NEVER to be used underwater. Never Ever!!!!!!! Let me repeat that in case it was missed: This exercise is for practice ON LAND ONLY, NOT / NEVER underwater (and this ‘type’ of breathing IS NOT / NEVER to be used underwater). Never Ever!!!!!!! :shakehead: :no:

    So, with that said, ideally to start with lay on your back on a hard surface and place a hand over your lower abdomen (i.e. below your ‘belly button’), as you want to make sure you are expanding your chest (i.e. lungs), not simply filling your abdomen with air. So, if your doing it right - no pun intended! - your abdomen should stay ‘flat’ (i.e. your hand does not move up and down) while you upper body ‘expands’ so to speak. (Note; if your abdomen is rising, your ‘doing it wrong’!)

    Once you have ‘mastered’ this technique as it were, then the exercise can be performed in any position (although there are no doubt some ‘positions’ :cuddles::giggle: I can think of when it may be difficult to perform :D). That is, standing, sitting, and even while walking (although the ‘while walking’ will certainly challenge your ‘at rest’ times :() is as good a place as any.

    Anyway, to the 'exercise';
    1. Breathe in for 5 seconds
    2. Hold in for 5 secs
    3. Breathe out for 5 secs
    4. Hold out for 5 secs
    5. Breathe in for 5 seconds, repeat 2, repeat 3 repeat 4, ad infinitum as it were.

    That is, continue to repeat the above sequence for a minimum of, at least, three to five minutes per session every day. (But of course, feel free to extend sessions longer than five mins, and / or do several five min sessions a day.) No doubt there are some folks here who can already start off right away with longer times than the above, but the above is a good starting point for most people to see where their breathing is at, so to speak.

    However, and this is very important, if after sequence #4 you need to ‘gulp’ air / can’t do whatever times you have set yourself, then you must reduce the sequence times until your not ‘gulping’ in that next breath. This is critical to the success of the exercise. And just doing one sequence is of no use, you must do at least several minutes per session to make an effect (although at first you might find you can only feel comfortable with a minute or two. That's fine / to be expected; extend as / when you can). Whatever, your times have to be so that you can repeat said sequence continually for several minutes before extending the individual sequence times (i.e. numbers 1 through 4).

    As you get more comfortable extend ALL the times. A reasonably fit person will find that they can extend the above times dramatically. Of course this doesn't happen overnight, as you have to stick with it to get the results/benefits. Of course there are limits on everything (aren't there?), so at some point you will hit a brick wall. But that wall is a lot further away than you might think.:thumb:

    I can't recall what my longest times were – nor do I any longer care - but lets just say 15 / 15 / 15 / 15 seconds was fairly quickly achievable (and easily sustainable for the duration of whatever length of time I choose to exercise) throughout my 40’s - when I first started doing said exercise - and on throughout my 50’s, after which time I unfortunately got lazy and did not do said exercise regularly but - unfortunately not by choice - nor do I dive regularly anymore either. (This ‘exercise’ has several other benefits also, but that's not what this post is about so we wont go there.)

    Anyway, you will only know if this exercise helps you if you have the inclination to, first try it and second, to persevere with it.

    NOTE: I would hazard to assume that this exercise is unlikely to improve the very very very low SAC rates claimed by some folks in this thread.

    DISCLAIMER #3. As stated above, this practice IS NEVER TO BE USED WHEN UNDERWATER. It is simply an ‘exercise’ to be used above water to instill in you an awareness that you have control over your breathing, and in the process help you to reduce your SAC rate.

    FINAL DISCLAIMER; Not sure if I mentioned this above :wink: but this exercise is for practice ON LAND ONLY, NOT / NEVER underwater (and this ‘type’ of breathing pattern is NOT / NEVER to be used underwater. Never Ever!!!!!!:shakehead: :no:
  9. Joneill

    Joneill Loggerhead Turtle

    # of Dives: 100 - 199
    Location: New Jersey, USA
    This seems opposite of what I've always read - which was that you should practice diaphragmatic breathing?

  10. Kay Dee

    Kay Dee Barracuda

    # of Dives: I'm a Fish!
    Location: Here, there, and everywhere
    Thanks for posting that link. And yes that's how I was 'originally' taught.

    But later I was taught the method I posted and found it 'worked' better (for me). Like I said in my post, I am no medico, etc, I only know what worked best for me (and some others).

    So, again like I said, feel free to take no notice what-so-ever regards the 'method' that I proposed. As we know, one shoe does not fit all after all.

    However, should any Mods feel it's "wrong / bad advice" I have given, then they should remove my post immediately!

    PS. I will make a small edit / add a couple of words to my post (in the section you quoted) as I can see an unintentional error (of mine while writing) in what I meant to say re hand placement. It should have read ".......and place a hand over your lower abdomen (i.e. below your ‘belly button’)............". Doesn't change much as to what I stated re method, but at least clarifies where to place your hand in the method I was referring to.

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