Nick Pelios
Freediver, Creator
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Nick Pelios
Freediver, Creator
Let’s be real. Waking up at 6 AM for a dawn dive feels impossible without a shot of espresso or two. Your body protests, your brain is foggy, and the ocean seems much less inviting when your eyelids weigh a metric ton. But what if I told you that your morning caffeine fix is quietly sabotaging your freediving game?
Alchemy partner and freediving instructor Josh Munoz put this to the test in his latest experiment, and the results? They might make you rethink your pre-dive rituals forever. Strap in, because we’re about to dive into the Mammalian Dive Reflex, a built-in superpower that helps you hold your breath longer, and the reason caffeine is its worst enemy.
Image by Josh Munoz
The Mammalian Dive Reflex is an ancient survival mechanism that kicks in when your face touches water, triggering several key physiological responses.
Slowed Heart Rate: Your heart rate slows dramatically, shifting into oxygen-conservation mode. Josh clocked his at a ridiculous 32 beats per minute while holding his breath at depth.
Vasoconstriction: Blood vessels in non-essential areas like your arms and legs tighten, rerouting blood to where it actually matters: your brain, heart, and lungs.
The Spleen Effect: Your spleen, the unsung hero of breath-holding, contracts to release extra red blood cells, boosting your oxygen-carrying capacity.
Blood Shift: Increased blood flow to your lungs prevents them from imploding under pressure.
Immersion Diuresis: That oh-my-god-I-need-to-pee feeling that every freediver knows too well.
In short, the Mammalian Dive Reflex is the cheat code for better, longer breath-holds. The catch? Caffeine screws with it.
Image by Josh Munoz
To prove just how much caffeine impacts freediving, Josh strapped on a heart rate monitor and performed a series of breath-holds, both with and without caffeine.
Without caffeine, his heart rate dropped to 32 beats per minute during a dive to 10 meters. Even with just his face in the water at the surface, his heart rate hovered around 40 beats per minute, showing how effectively the reflex conserves oxygen. Then came the Red Bull experiment.
After chugging caffeine, his heart rate on land spiked to 75 beats per minute, about 20 beats higher than before. In the water, he was only able to bring it down to 50 beats per minute. This clearly demonstrated that caffeine prevented the full activation of the Mammalian Dive Reflex, keeping his heart rate elevated and his oxygen consumption high.
Image by Josh Munoz
Look, I’m not here to ruin your life. If a morning coffee is your one true joy, I get it. But if you’re serious about maximizing your freediving performance, you might want to rethink that pre-dive espresso. Josh’s advice is to at least skip caffeine on dive mornings. Let your body do its thing. Trust the Mammalian Dive Reflex. Your heart rate and your dive time will thank you.
The ocean doesn’t care about your caffeine cravings, but it does reward those who can slow down, breathe deep, and embrace the silence.
Image by Josh Munoz
The Mammalian Dive Reflex slows your heart rate and conserves oxygen, helping you hold your breath longer. Caffeine keeps your heart rate unnaturally high, sabotaging the reflex and burning through oxygen. Josh Munoz’s experiment showed a significant difference in breath-holds with and without caffeine. If you want longer, easier dives, ditch the coffee before you hit the water. The ocean is calling. Maybe leave the Red Bull behind this time.