Air consumption - It's not a competition

How many times have you surfaced from a dive to be asked, by a fellow customer, "how much air do you have left in your tank?" It's not competition - we are all different and on different days we all breathe in different ways.  That's my standard answer - even though I can usually show off with half a tank left after a 60 minute dive.  (and I'm not alone btw).

It's always a mystery to me as to why, when some divers put a regulator in their mouth, their breathing rate instantly quadruples and they suck air from the cylinder like it's going out of fashion.  We frequently meet divers who (kindly) tell us in advance that they will be back on the boat in less than 30 minutes due to running out of air, and they really really wish they could do a full hour's dive.  

Even more of a mystery is why many divers rarely (never) ask for help with breathing techniques.  I've offered a colleague (to remain unnamed (*)) of mine time in the pool where I can pass on some techniques that I guarantee will decrease their air consumption (assuming they listen) but my offer has always been (less than) politely declined.  Wonder if they're scared I may actually know something! Joking and jibes at my colleague aside, it is possible to improve your air consumption with a change of technique, practise and perfecting your buoyancy control & finning techniques.  First of all some facts: -

Women do breathe less than men

Sorry guys - it's just the way it is on the whole.  We're smaller.  That means we have smaller lungs.  That means every time we inhale we take in less air than you. Not much any of us can do about that.  In addition, the bigger someone is, there is more muscle & body tissue needs to be supplied with oxygen - which is why our lungs will grow in proportion to our bodies.

The more you dive the less you breathe

The more you dive the more comfortable you will become and the more relaxed you will be.  The more relaxed you are the lower your breathing rate, and therefore the longer it is until you need to end your dive.  How many of you know that on your first dive on your first dive vacation in 18 months you will get through that cylinder faster than you did on your last dive all that time ago? 

If you're over-weighted you will breathe more

Carrying excess and unnecessary lead weight will exert your body more than if you don't.  Perfect your weighting and you may just end up amazed at the improvement in your air consumption.  Not only will you save air by not having to constantly add and adjust the volume in your BCD, the easier you will find it Many years ago I worked at a dive centre that offered concierge diving - one week we had a lovely gentleman who told me on day 1 that he would never manage to stay underwater more than 30 minutes due to his air consumption; he also told me he needed 28lbs (yes, that's 28lbs) of lead.  I politely suggested otherwise but was told I was wrong.  Fast forward to day 3 and I'm changing his equipment to a fresh tank for his second dive when I 'accidentally' managed to lose 10 lbs of lead from his rig.  I didn't tell him.  He surfaced a full 45 minutes after his descent announcing that was the best dive of his life, he'd never felt so comfortable and he'd never stayed down for so long.  I confessed.  He bought me a pair of Oakley sunglasses to say thank you.

Master your kicking techniques

The more efficient you are at kicking, the less energy your body uses, meaning the less carbon dioxide it produces and the less oxygen it will need.

Physical fitness is important

Simply - the fitter you are the better performance your body will give you, reducing your need to breathe.

There are no quick fixes

Yes there are techniques but everything takes time and practise so manage your expectations as to what can be achieved.

In order to improve your breathing it's important to understand some of the science behind what happens when we inhale.  Most gas exchange occurs in the lower third of the lungs - when you inhale it's important to breathe in deeply and really fill your lungs from the bottom to the top.  This allows oxygenated air to reach the parts it needs to reach.  There is an important muscle supporting your lungs - the diaphragm muscle - learning to breathe using this muscle means that on every inhalation your stomach will expand as the muscle contracts downwards allowing you to fully fill your lungs.  When you learn how to control this muscle you will immediately be breathing less due to allowing a more efficient gas exchange.  Eliminating "dead air" is also important - we metabolise roughly a quarter of the 21% oxygen (in air) when we breathe, and we produce carbon dioxide (CO2) as a waste product.  Proper exhalations mean that the CO2 will be removed from our body and, when combined with proper inhalations, mean it's replaced with fully oxygenated air.  Simply - if we aren't breathing properly the gas exchange will become inefficient and we will need to breathe more to ensure our body has the oxygen it needs.

In layman's terms - if you have ever smoked you will know it's common for smokers to do a quick yet deep inhale filling their lungs with their smoke of choice.  Most will then "pause" their breathing for a short moment (never quite holding their breath) before a long and slow exhale.  Try this technique on scuba.  One quick and deep inhale, feel the diaphragm muscle contract downwards expanding your stomach, then exhale slowly counting to 5 (or more) as you do.  Feel that muscle contract upwards as you exhale.  And repeat.  This is the same technique that is used by many singers and wind/brass instrumentalists.

[true story - last year a diver was able to manage around 45 minutes underwater surfacing with 500 psi; I verbally gave her this technique (we did no in-water sessions); the following day she managed a full 60 minutes and surfaced with 1,000 psi.  Similar dive profiles.  It works].

Others prefer the long inhale / long exhale technique.  Spend some time picking the length of breathing for you - I'd suggest you start with "5"- when you inhale slowly count to 5 in your head, feel the diaphragm muscle contract down expanding your stomach.  When you exhale count the same and see if you can extend by 2.  Count 5 in.  Count 7 out.  Work out what's best for you - this technique is one used during yoga.

And for the scuba geeks - want to know how to work out your Surface Air Consumption rate (SAC)?  Pick a depth on your next dive, write down your SPG reading and stay at that depth for 10 minutes, write down your SPG reading at the end.  Do not exceed your no-decompression limit!  Then do the maths: -

METRIC:

for litres per minute (l/min): 

((bar used) x (cylinder volume in litres)) [divided by] ((depth in metres + 10 metres) / 10)) [divided by] time in minutes

IMPERIAL:

for cubic feet per minute (cf/min):

((psi used/ full pressure) x (capacity in c.f.)) [divided by] ((depth in feet + 33 feet) / 33)) [divided by] time in minutes

There is no "normal".  We are commonly asked how long a cylinder will last - and we don't have the answer.  Everyone is different and "your normal" will depend on size, fitness, sex and workload in the water.  We aren't looking for normal breathing, rather optimum breathing and the answer to that will always be "slow and deep".   Diving is meant to be calm & relaxing - your breathing should be the same.  The truly dedicated diver looking to improve air consumption may wish to take up yoga or singing - both of which teach controlled breathing techniques that transfer well to scuba.  For the rest of you - first perfect your buoyancy & kicking techniques - the Peak Performance Buoyancy course is there for the taking; secondly - dive, dive and dive again!  I promise that with correct weighting and experience you cannot fail to improve.

* special brownie points will be awarded to anyone who correctly guesses which Divetech staff member has rejected a session of my sage advice.