Happy Sunday from S. Padre Island, where I'm working away, waiting on the wind. As you've noticed, I've been pummeling your neurons all week. You've survived a week of my unloading a significant portion of my brain into your inbox on temperature, pH, lactate, ketones, CO2, cross-adaptation, and one Canadian firefighter whose heart rate hit 190 in a burning building. That's a lot of physiology for a week. Some of you read every word, and I'm sure a few of you got three deep and then life...

I want to tell you about Andrew Martin. Andrew is a firefighter in Canada, which already puts him several levels above the average physiology dork pontificating about “resilience” from a climate-controlled office with a laptop, an Oura ring, and the emotional intensity of damp toast. He’s been collecting heart-rate data during actual emergencies. Not lab-coat pageantry on a moving belt. This was not a simulation cooked up in a lab with ethics forms, safety rails, and some intern holding a...

In this episode, I sit down with respiratory and sleep scientist Martin McPhilimey to take a deep dive into breathing, CO₂ regulation, and how they actually impact performance, stress, and sleep. We get into why respiratory physiology is way more complex than most people think, how his clinical and research background shaped his approach, and why breathwork exploded during COVID with names like Wim Hof and James Nestor. From there, we dig into allostatic load and why piling on high-stress...