HERE IS A LITTLE experiment you can try while reading this month’s DIVER. Plot out a route around your house, office or garden, one that you can easily follow without crashing into things, or having to stop to open doors.
Think about this route, because you’re going to have to walk round it soon.
Now stand up, and run up and down on the spot for a minute. There’s no need to overdo it, just enough to know that you’re doing some exercise.
Your heart will be beating faster and you’ll be breathing harder. You may want to mark this page to avoid losing your place.
Now exhale, pinch your nose, close your mouth, hold your breath and walk the route. No deep breath first, and no rest before this part of the experiment.
The idea is not to push this to the limit, but to see how far you can get and still be comfortable when you stop.

UNDER WATER, IT WOULD BE COMFORTABLE enough to give an out-of-air signal and receive a regulator from your buddy without panicking and putting you both at risk. If you like, you can carry DIVER with you and continue reading through this part of the experiment.
Note how many circuits and part-circuits you have completed, then return to the start and spend a few minutes just settling down. This isn’t a deep yoga thing yet, just resting to get back to a more normal breathing and heart rate.
Now breathe out, pinch your nose, close your mouth, hold your breath and walk the route again. Note your distance, then return to the start.
We’re going to do this one more time. But this time, first concentrate on relaxation and calm, effective breathing.
You will need to stop reading and mark the page, because you’re going to stand at ease, close your eyes, relax, and breathe regularly and steadily in and out from the diaphragm, not the chest.
This is not hyperventilation, just chilling out.
If you can do all that without nodding off, after a few minutes it’s time to breathe out, pinch your nose, close your mouth, hold your breath and walk the route yet again. Oh yes, don’t forget to open your eyes.
Now compare the distances.

THIS IMPROVISED EXPERIMENT was inspired by a standard IANTD training drill led by instructor Phil Short at last summer’s Vobster TekCamp. As a warm-up exercise one morning, they had 40 divers and instructors walking marked lines in the car park.
“Being able to control one’s breathing, heart rate and stress levels is very, very conducive to survival in emergency situations during diving,” said Phil.
“This exercise gives the diver an appreciation of the difference between having to deal with an emergency while out of breath because they’ve been overdoing it, swimming hard against
the current and not pacing themselves; on normal dive conditions, so just pootling along with a buddy; and then when using proper breathing techniques, slowly and calmly.”
The line length used is 18m, because that is the distance used by IANTD (and other technical agencies) for out-of-air drills during the confined-water part of all their courses.
“We get them to exhale before walking the line, because in a real emergency they would typically exhale, go to take the next breath in, and it doesn’t work. So they have to go to a buddy.
“Let’s face it, buddies don’t dive on top of each other, they dive within the range of visibility a lot of the time, which is wrong, and part of what this drill is trying to point out,” said Phil.
“On the first walk, most won’t make the 18m. On the second walk, they almost invariably double their previous distance and, at the end, when they decide that is enough, they will actually feel a lot better, a lot less stressed, a lot less desperate for a breath.
“On the third walk, they typically extend the distance by the same again, so cover three times as much distance as on the first walk,” said Phil.
“By adopting a controlled breathing pattern while diving, if an emergency occurs you’re better prepared to deal with it smoothly, easily and comfortably. Correct breathing is from the diaphragm, like that taught in yoga or martial arts, or in pre-natal classes,” he explained.

I ASKED SOME OF THE PARTICIPANTS what they thought of the exercise.
“It emphasised how being relaxed and calm can give you that much more time in a stressful situation,” said Shelley Sutre. “The increased distance you can cover is amazing compared to the high stress, high heart rate.
“The middle exercise was a big difference from the first. The third exercise made a small difference again.”
“It certainly made the point,” agreed Philip Sherley, clarifying the breathing technique as “breathing with your stomach going in and out.”
“It wasn’t so much as how far I got along the line, as how much better I felt when I got there,” said Andy Clarke.
“On the first part, after the run, it was literally starting to make my head spin. When calm and focused, the recovery time was so much quicker. I didn’t get the same stars and spinning of my head.”
“I more than doubled my distance over the whole exercise,” put in Kerri Clarke.
“I did the calming exercises before getting in the water later on,” added Andy. “It was hot, hard work kitting up, so I just sat and focused for a bit. Things came into place.”
Which brings us to the possibilities of taking such an exercise into the pool, or confined water. “On a training course, this exercise would be repeated in confined water with the equipment the course requires,” explained Phil Short.
“It’s very important to emphasise that this is not a competition with the other divers, with the instructor or most importantly with themselves.
“I would rather see divers travel less than the length of the line and execute an out-of-gas drill smoothly and progress from that with practice, than to race for distance and struggle to take a share at the other end,” said Phil.
“For safety, it’s always done on a horizontal line in shallow water. When they breathe out they keep the regulator in their mouths, and remove it only when they’re ready to receive gas.
“The instructor is right by them. So if anything goes wrong they can just take a breath, or the instructor is ready to donate.
“We get them to use their hands to pull and glide, rather than swimming with their fins. There is plenty of physiological evidence that hard flutter-kicking with the powerful leg muscles burns more oxygen than any other muscles in the body,” concluded Phil.
“I had done an 18m breath-hold swim on a course, but without the advice to use your hands,” said Kerri.
“Everyone has been so obsessed with keeping your buoyancy and trim, said Andy. “It’s weird to hear from someone at Phil’s level say that if things go that badly you just need to get to the air source.”

I ASK WHETHER THIS IS SOMETHING divers could do on their club pool night.
Phil agrees that any group of qualified divers could work together on such an exercise. “I’d tie a rope between two ladders so they have something to pull on with their hands. Swimming-pool tiles are slippery to get a grip on.”
I also ask whether they should do it after some exercise or by finning for comparison.
“Definitely not,” said Phil. “Under water you should only ever do this the right way, pulling with your hands as much as you can. To do anything else could actually create an emergency during a training drill.
“Learning about the wrong way of doing things is limited to the car park, where it’s safe.”
Being at TekCamp, I will leave the last word to one of the participants about putting this to use under water. How has it helped them
“Just focusing on my breathing throughout the dive,” said Andy Clarke. “Just being aware of when it’s getting a bit high, taking some time to focus and relax and get things under control.”