Sauna, ice bath, cold shower and 17 more — each with a protocol, instructions and an honest rating of the evidence.
Three things the app keeps track of for you. The sources are listed at the bottom of the page.
The ring fills at four applications per week. Below it you see how often it was heat and how often cold — and how many weeks you've kept it up.
Example: week of 26 Oct to 1 Nov
6 applications that week — the ring was full on Friday.
Each of the 20 applications has a protocol, instructions, a reason with a source — and a rating of how well it's supported.
20 types
Only 2 of 20 are strongly supported, including the sauna. The app tells you so instead of making everything sound equally good.
Start an application and a timer runs along. The app counts rounds for you, and you can add the temperature.
A long press on an application opens its info sheet: protocol, how to do it, what happens in the body, and a safety line.
In a Finnish study of 2315 men, those who used the sauna 4 to 7 times a week died less often from cardiovascular causes over about 20 years than those who went once a week.1 That's a link, not proof.
The protocol in the app
Cool down and rest after each round. You lose about 0.5 litres of sweat per round.
From the easy start to the cold chamber — with what the app recommends.
Protocols in the app
Never take an ice bath alone. If you have cardiovascular problems, check heat and cold with your doctor first.
In a study of 21 men, those who spent 10 minutes in cold water after every session gained less strength and muscle over 12 weeks than those with active recovery.2
The authors advise against using cold as regular recovery after strength training if you want to build muscle.
An analysis of 11 studies with 3177 participants found more signs of inflammation right after cold water, but less stress 12 hours later.3
After 24 hours no difference was visible. The app rates the ice bath as “moderate” evidence.
The app already calculates these connections today. A connection is not a cause — but it shows you where to look.
For each sauna round the app adds 0.5 litres to your hydration goal. Without a round count it assumes one round per 15 minutes — only for the Finnish sauna.
For your blood values, the app also names applications that could fit — as a note, not a diagnosis.
Without active calories from your watch, the app adds sauna and ice bath to your daily expenditure — using its own estimates.
In a Finnish study of 2,315 men (aged 42 to 60, followed for over 20 years), more frequent sauna bathing was linked to fewer cardiovascular deaths: 4 to 7 sessions a week compared with one a week. This is an association from observation, not proof of a cause.1
In a study of 21 men, those who spent 10 minutes in cold water after every session built less strength and muscle mass over 12 weeks than those who recovered actively. The authors advise reconsidering cold water as a regular recovery strategy after training.2
A new article every Friday.
Biohacking & Lifestyle · Heat & heartSauna & heart health: what the Finnish studies showRegular sauna use is more than relaxation: large long-term studies from Finland link it to a healthier heart and a higher life expectancy. What lies behind it.Read more
Biohacking & Lifestyle · Cold & RecoveryCold therapy & ice bath: hype or real benefit?Ice baths have become a longevity trend. What cold water triggers in the body, what research has proved so far – and how you start safely without overdoing it.Read more
Biohacking & Lifestyle · Light & CellRed light & infrared: what light therapy can really doRed-light panels promise better skin, faster recovery and more energy. What lies behind Photobiomodulation, what is backed by evidence – and where the hype outpaces the data.Read moreEvery statement comes with its source; the figures are taken from the linked studies and opinions (checked on 1 November 2026). This is context from the research, not a diagnosis and no substitute for medical advice.
Get YUTHI from the App Store — iPhone first, from November 2026.
