If you’re a swimmer, you have probably felt that chest-busting desperation to breathe. I often end my swimming sessions with a length under water, and felt that tingle in my arms, the swimming head as my body demands an inhalation. It’s not the nicest feeling, so the idea of hypoxic training sounds horrible.
There’s no doubt that hypoxic training is contentious. Or at least the terminology: I know babies who have been brain damaged by hypoxia during birth, and there are cases of people who have drowned by attempting to hold their breath for too long. In August 2015, the incredible free-diver Natalia Molchanova, who had been able to hold her breath for around nine minutes, went for a dive and never resurfaced, proving that even the most incredible humans need to breathe.
The theory behind hypoxic training goes like this: athletes who train at high altitudes become efficient, oxygen-processing machines. Among other benefits, this means their oxygen-deprived bodies produce more haemoglobin, which carries more oxygen to their muscles, thus improving performance.
Hypoxic training is supposed to stimulate training at high altitude. You’re asking your body to respond to the same physical demands of normal training, but with less oxygen. Your body then gets better at using oxygen, so when you go back to swimming normally, you have an abundance of it, making swimming further, faster and harder easier than it was before.
It’s a really common part of swim training, and many coaches use it to help improve swimmers’ stamina and performance. Really, all it means is breathing less often for a part of a training session; every 3, 5 or 7 strokes.
There’s an argument against it, though, which says that actually all you’re doing is breathing less often rather than taking on less oxygen, and there’s a danger that you’re increasing the amount of carbon dioxide in your blood. Also, that your age and physical condition means that you might be physically unable to achieve what you’re supposed to be achieving: a swimmer in their 50s has less lung capacity than one in their 20s, regardless of training.
Another, quite persuasive argument, is that it’s really dangerous. There have many cases of qualified, capable athletes dying or nearly dying after blacking out during hypoxic drills or challenges. In New York in May, pools actually banned this kind of training. If you want to read about what happens to cause this, there’s a good article here.
But, when you swim in open water, the demands on your breathing change. The cold, quite literally, takes away your breath. If you’ve wrapped your chest in neoprene, chances are you’ll struggle to expand it enough to catch your breath again. It was the biggest shock to me when I first swam in cold water in a wetsuit; I just couldn’t regulate my breathing.
So even if the physiological benefits are dubious, there’s a strong argument that including some kind of breathing control to your pool training session will have massive advantages for when you swim in open water. You also need to learn to breathe to both sides so that you can adapt to currents and choppiness in open water.
I find a gentle build every 25 meters a good way to start. I naturally breathe every three strokes, so I’d start with 25m on three, 25m on five, 25m on seven, 25m on five, 25m on three. The most important thing is that you don’t hold your breath, you trickle out a stream of bubbles between breaths to avoid build up of CO2.
If you breathe every two strokes, try breathing every two on the opposite side to the one that feels normal. This is enough of a challenge, and you’ll really have to think about your breathing.
So the key isn’t hypoxic training, it’s learning breathing control. Slow, rhythmic, regulated breaths much like the kind you might do when practising Yoga or meditation will calm you, and help you cope with open water swimming. Try it now: take a big lungful of air right down into your stomach, then slowly exhale.
This is a skill you’ll then be able to take outdoors. I almost sing the rhythm of my breath when I’m in the lake of river because it helps me calm and regulate my breathing.