koldwr

World's first underwear engineered for Bryan Johnson's sauna icing protocol.

[koldwr @koldwr]

15 minutes in a sauna.
74 days of damaged sperm.
Bryan Johnson figured out the fix: ice the boys.
We made it wearable.

[koldwr @koldwr]

@bryan_johnson Tldr: ice your balls ✅

[koldwr @koldwr]

Kits boxed up and ready to ship. Every unit going to people who've been waiting since the early waitlist days

If that's you, your email is coming soon. 📦

[koldwr @koldwr]

@AlpacaAurelius This is the way

[koldwr @koldwr]

alwyas remember to always ice your balls in the sauna

[koldwr @koldwr]

@PathOfMen_ icing your balls is the way to go

[koldwr @koldwr]

exactly why you should ice your balls in the sauna

[Bryan Johnson @bryan_johnson]

I put ice on my balls during sauna and my motile count went up 57%. Then I removed the ice and motility crashed 57%.

238 sessions to learn that the most important variable in my sauna protocol was a bag of ice on my groin.

I am a serious scientist.

[koldwr @koldwr]

@bryan_johnson hey @bryan_johnson we built a product inspired by you, for exactly this

[koldwr @koldwr]

@SahilBloom dont forget to ice your balls in the sauna

[koldwr @koldwr]

@Toddlickthis They are 88% Polyester + 12% Spandex.
Cotton coming soon!

[koldwr @koldwr]

15 minutes in a sauna.
74 days of damaged sperm.
Bryan Johnson figured out the fix: ice the boys.
We made it wearable.

[koldwr @koldwr]

@scmedicinals add icing balls to the stack and you're good to go

[koldwr @koldwr]

POV: you started icing your balls in the sauna

[Michael Caporale @SurrealBlend]

Someone finally made them. @bryan_johnson would be so proud 🥲

[koldwr @koldwr]

@SurrealBlend @bryan_johnson We would send him a pair for feedback!

[koldwr @koldwr]

The 15-min and 74-day numbers come from Garolla et al. 2013, Human Reproduction (Oxford Academic). 10 men, sauna 2x/week for 3 months — significant drops in sperm count, motility and DNA quality. https://t.co/WqWmhKA89T
Bryan's ice-pack data is his own n=1 follow-up. The heat-damages-sperm part is peer-reviewed.

[koldwr @koldwr]

@KunleCampbell you know it!

[koldwr @koldwr]

@No_i_c0 https://t.co/DKt47CRgjr

[Bryan Johnson @bryan_johnson]

Sauna is one of the most effective health protocols I've done. Here is everything I've learned; it's the most robust characterization ever produced.

Results:

1) Fifteen sessions of sauna dramatically reduced environmental toxins in my body:

+ 65% drop in 2,4-D
+ 100% drop in MEP
+ 15% drop in MBP
+ 100% drop in MEHP (undetectable post sauna)
+ 56% drop in NAPR
+ 56% drop in HEMA
+ 100% drop in Perchlorate (undetectable post sauna)

2. Sauna eliminated 85% of microplastics from my ejaculate.

Nov 2024:
165 particles/mL
July 2025: 20 particles/mL

Nearly identical drop in my blood same time period:
Oct 2024: 70 particles/mL
May 2025: 10 particles/mL

3. Sauna, without ice on the boys, devastated my fertility markers.

Total Motile Count: –56%
Concentration: –30%
Motility: –50%
Morphology: –48%
Count: –9%

4. Sauna coincided with my fertility markers being at an all-time high. I have more total and motile sperm than 99.6% of men of any age, including men under 25.

+ total count: 600 M
+ concentration: 162 M
+ motility: 55%
+ total motile count: 330M
+ morphology (normal): 10%

We do not know what to make of these improvements. Was it the sauna? Sauna + ice? Ice only? We don't know but we did not identify any other protocols or lifestyle changes during this interval that would plausibly account for the change.

5. My vascular function improved by a ten year reduction in age. Now I have the vascular age of an elite 18-early 20s.

+ Central Systolic Blood Pressure: 96 mmHg
+ Central Pulse Pressure: 20 mmHg
+ Pulse Pressure Amplification: 160%
+ SEVR: 227%
+ Augmentation Pressure: 1 mmHg
+ Augmentation Index Wave: 3%
+ Traditional blood pressure: 107/75 mmHg

6. What type of sauna?
Use a dry sauna with high temperatures between 80-100°C (176 to 212°F) and 5-20% relative air humidity. Aim for the lower end of this spectrum, especially as a beginner. Higher temperatures closer to the boiling point can cause side effects like headaches and severely dried nose and eyes.

Note: Steam baths, hot tubs, and infrared saunas fail to replicate the same effects because they do not allow you to safely reach the required high temperatures and do not induce the same level of sweating, the necessary inverted (skin-to-core) temperature gradient, and the massive re-direction of blood to the skin with resulting vasodilation.

Dry sauna is unique, and very likely superior to wet (steam bath) and infrared saunas. By heating up your skin way faster than your core, dry hot sauna flips your core skin temperature gradient, eliciting the following hormetic benefits:

+ enhanced blood flow: the heart pumps up to 70% more blood, similar to intense aerobic exercise (zone 2-+ increased sweating for detoxification: to maintain a stable core temperature, the skin produces 0.6-1 liter of sweat per hour, facilitating significant detoxification.
+ improved heat tolerance: the body becomes better at handling heat, leading to a lower core body temperature (offering metabolic advantages)
+ safe activation of heat shock proteins: the skin experiences substantial heat shock protein activation, while a modest 1°C increase in core temperature is sufficient to activate these proteins without the risk of hyperthermia.
+ extended Exposure at higher temperatures: dry saunas are more tolerable for longer durations and at higher temperatures, maximizing the benefits.

7. Sauna protocol and frequency
Type: hot dry sauna
Temperature: 176–212°F ( I do 200°F)
Relative air humidity: very low, 5-20%
Duration: 20 min
Frequency: 4–7x a week

8. Heat Protection

If you'd like, you can protect your head from the heat by wearing a sauna hat or wrapping it with a towel (use only cotton or other 100% natural material). You can breathe through a towel or cloth if needed to protect your nose. I am personally fine not doing this.

Most importantly, ice the balls.

Icing the testicles is absolutely required to prevent heat from damaging fertility markers.

+ Ice the testes during the sauna session.
+ Use a non-toxic, reusable ice pack material.
+ Wear cotton boxers and shorts.
+ Place ice packs in between the boxers and shorts.
+ Keep them in place for the entire session.

Men should care about preserving fertility markers even when they are not trying to conceive. Sperm quality is tightly coupled to testicular function, which governs testosterone production, metabolic health, and long term endocrine stability. When fertility parameters decline, the same upstream dysfunction often drives lower testosterone, higher inflammation, and increased cardiometabolic risk.

9. Hydration

Dry sauna induces sweating as part of its beneficial mechanism. Be sure to hydrate properly. In general, you might need to rehydrate with up to 16–32 oz (0.5–1 L) of fluid after a sauna session. Be sure to add electrolytes.

If you want to be precise, measure your sweat amount and electrolytes (saltiness) using a patch (e.g., from Gatorade) to quantify your liquid and electrolyte loss, and rehydrate accordingly. Some people have saltier sweat than others and must ensure they replenish electrolytes as well as water.

My results: my body sweats 18 oz during a 20 min sauna at 200 °F, with a sodium concentration of 25-39 mg/oz. A single sauna session flushes 450–700 mg of sodium out of my body.

#

I wish you all the best in life my friend. A new era or being human is here. One where existence is the highest virtue. Prioritize sleep, daily exercise and eat well and you'll be in a strong position. Try to avoid the bad stuff. Anything that takes away your agency.

Be a warrior and caretaker of existence. Don't Die.

[koldwr @koldwr]

@les_pibis_ Good!

[koldwr @koldwr]

@bryan_johnson i hope you iced your balls as well

[koldwr @koldwr]

https://t.co/XbKoeFoMP2

[koldwr @koldwr]

Sauna for Men 101