Vol. 1 · No. 1 · July 2026
The current issueDepartment · 5 listings
Heat and cold are training stimuli, and the response shows up in the same metrics athletes already track: plasma volume, resting heart rate, HRV, sleep. A ring or band closes the loop — you can watch a three-week sauna block lower your resting heart rate the way the endurance studies describe. Red light and PEMF round out the recovery stack for the post-session wind-down.
The ScienceJuly 2026
Post-exercise sauna raised trained runners' endurance 32% in three weeks. A ring or band lets you watch the same adaptation happen in your own resting heart rate.
“Three weeks of post-run sauna: plasma volume up ~7%, time-to-exhaustion up 32%. The adaptation is real, and it's measurable.”
InsideWhat the performance research found · What to watch, and the recovery stack
Read the article5 min
Run to exhaustion
+32%
Three weeks of post-run sauna bathing increased trained runners' time to exhaustion by 32% — on par with roughly 2% off a 5K time.
The fix: A wearable shows the adaptation happening: plasma volume up, resting heart rate down.
From the screening room
How to Increase Athletic Endurance and Muscle Mass through Sauna Use with Dr. Rhonda Patrick
Dr. Rhonda Patrick · FoundMyFitness
Patrick focuses on hyperthermic conditioning, explaining how heat acclimation boosts plasma volume, endurance, and heat-shock-protein-driven protection against muscle atrophy. Strong pick for the recovery and performance angle.
What actually helps
Heat is a training stimulus. The interesting part is watching your physiology respond to it.
Field NotesJuly 2026
A traditional sauna runs hotter than any wrist tracker is rated for. Here's what actually happens to a WHOOP, Apple Watch, or Oura ring in the heat — to the hardware, and to the readings.
“The sauna isn't dangerous to you in a way your tracker will catch — but it's well outside the temperature every one of these devices is built for, and the data shows it.”
InsideThe heat is outside every device's spec · Why the readings go haywire · How to do it without wrecking the device or the data
Read the article5 minThe science
Heat and cold are training stimuli, and the response shows up in the same metrics athletes already track: plasma volume, resting heart rate, HRV, sleep. A ring or band closes the loop — you can watch a three-week sauna block lower your resting heart rate the way the endurance studies describe. Red light and PEMF round out the recovery stack for the post-session wind-down.
Three weeks of post-exercise sauna raised competitive runners' plasma volume ~7% and time-to-exhaustion by 32%. · Journal of Science and Medicine in Sport, 2007
Improved sleep and wellbeing are among the most consistently reported effects of regular sauna bathing in the systematic-review literature. · Evidence-Based Complementary and Alternative Medicine, 2018
The Monthly Dispatch
New saunas and gear worth knowing about, session protocols, and the heat-therapy research behind them. No spam, unsubscribe anytime.