Contrast

Weekly cold and heat

BorrowedBased on research into a closely related measure, applied here to sauna and cold.
What it is
Your weekly minutes of cold and of heat, next to the routine of a group of experienced winter swimmers, and your cold minutes by water temperature.
How it is measured
Minutes in every cold round (plunge or cold shower) and every hot round (sauna, hot bath or hot shower). The rings show this week; the chart shows the last 12 weeks. Cold minutes are also split by the plunge's water temperature: below 10 °C, 10–15, 15–20 and 20 °C or warmer. Showers have no water reading and are counted apart.
How to read it
A Danish study of experienced winter swimmers reports their routine as about 11 minutes of cold and 57 minutes of heat a week, over 2–3 visits, in water of about 1–9 °C. It's a reference point from one group of people, not a target. Colder water is a stronger stimulus: the cold shock is largest between 10 and 15 °C and below.
What it cannot tell you
The study was small (8 winter swimmers), of young healthy men, and it measured metabolism and brown fat rather than long-term health. Whether minutes of plunging do what hours of mild cold do in the brown-fat studies hasn't been tested. An arm out of the water gives no temperature reading.

Sources

Every one of these ships inside the app, with the finding written out so you do not have to open the paper to know why it is there.

  1. Søberg S, Löfgren J, Philipsen FE, et al. Altered brown fat thermoregulation and enhanced cold-induced thermogenesis in young, healthy, winter-swimming men. Cell Reports Medicine, 2021.

    Men who dipped in cold water 2–3 times a week, most of them also using a sauna, burned more energy when cooled than men who did neither. They reported about 11 minutes a week in cold water and 57 in the sauna.

    doi.org/10.1016/j.xcrm.2021.100408

  2. Tipton MJ, Collier N, Massey H, Corbett J, Harper M. Cold water immersion: kill or cure? Experimental Physiology, 2017.

    The cold shock response peaks in water between 10 and 15 °C and below; the review also weighs the claimed health benefits of cold water against its risks.

    doi.org/10.1113/EP086283

  3. Cain T, Brinsley JH, Bennett H, et al. Effects of cold-water immersion on health and wellbeing: a systematic review and meta-analysis. PLoS One, 2025.

    Across 11 studies using water of 15 °C or colder, stress was lower 12 hours after immersion and sleep quality improved, with a short-lived rise in inflammation.

    doi.org/10.1371/journal.pone.0317615