Why do I need to pee when I dive?
It’s not the most glamorous topic, but it’s something that all my students ask me – why, despite our best preparation, do we need to pee when immersed in cold water? Well, here’s the information you need to be the world’s most enlightening conversationalist in any dive site car park…
Around a year ago, we took members of the Abyss Scuba Diving Club to the Department of Diving and Hyperbaric Medicine, a state-wide service located at the Prince of Wales Hospital in Randwick, Australia. Associate Professor Michael Bennet addressed a wide-eyed collective of scuba divers about their state-of-the-art recompression chamber and how they study and treat decompression sickness in their facility. However, the question many were just ‘busting’ to ask this decorated medical professional, was ‘why do we always need to pee in our wetsuits?’.
Professor Bennet gave an interesting response, describing the physiology around this phenomenon. I asked him to share it with us for this blog, as it was fascinating and comforting to hear that diving doesn’t make us all dysfunctional! There are real reasons as to why we experience this phenomenon.
“When you jump in the water, the increased pressure of the water around you (particularly during the times you are upright) squeezes blood up into the abdomen and chest (a bit like compression stockings). This has a few effects, one of which is that it stretches the heart a little bit – and this increases the release of hormone called ANP (atrial natriuretic peptide). This signals that you are full of water and increases your urine flow. And hey presto – you need to pee!” says Professor Bennet.
But don’t let this stop you hydrating properly before and after every dive. Your body is essentially getting a false reading and you could actually be quite dehydrated! When you exit the water, the reverse can happen.
Bennet adds, “For the same reason, you tend to become a bit dehydrated after every dive – when you get out of the water, the blood pools out in the periphery again and your heart and brain sense that you are short of water and you feel thirsty.”
Remember, drinking H20 goes a long way to preventing other problems like Decompression Sickness, so sometimes the best thing could be to drink up, give in, and get yourself a bottle of good old Mirazyme!