01
Pair
Connect a Bluetooth heart-rate sensor to the operator’s device.
Cold immersion · measured
DOWNSHIFT
See how quickly your body moves from shock back toward calm.
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Session complete
Shoulders · 52°F
86.4/100
Downshift Score
62
Baseline bpm
98
Peak bpm
ImmersionRecovery
The protocol
One calm minute.
Ninety seconds in the cold.
02
Settle
Sit and breathe for 60 seconds to establish your personal baseline.
03
Plunge
Enter the water. The operator marks the moment and the clock starts.
04
Measure
After 90 seconds, your heart-rate curve and Downshift Score appear.
The score
Your cold-shock recovery, made visible.
Cold water makes your heart rate jump. Downshift measures how far and how fast it returns toward your own resting rate—not anyone else’s—across the first 90 seconds in the water.
10nine-second segments
100possible points
90stotal measurement
Each nine-second segment earns up to 10 points for sitting at or below your baseline. Water temperature and immersion depth adjust the result, so a colder, deeper plunge is credited fairly. Scores read as Exceptional (80 and up), Strong (60–79), Moderate (40–59) or Limited (below 40).
Baseline, peak, recovery time, seconds below baseline and the full heart-rate curve are reported alongside your score—in the app and, after you sign in, on this site.
Connected sensing
Bring the strap you trust.
Downshift works with standard Bluetooth heart-rate sensors. The Polar H10 is the reference instrument.
| Sensor | Connection | Type |
|---|---|---|
| Polar H10 / H9 | Supported | Chest strap |
| Garmin HRM / Wahoo TICKR | Supported | Chest strap |
| Polar OH1 / Verity Sense | Supported | Optical armband |
| WHOOP 4.0 / 5.0 | Broadcast mode | Wrist |
| Apple Watch | Not supported | — |
Optional connection
Put every plunge in context.
Connect WHOOP to see your plunge beside daily recovery, sleep, cycles, and strain. Import up to 180 days of history, then sync about once a day.
Opt-in, revocable, and never required for a Downshift session.
Recovery
Sleep
Cycles
Workouts
Privacy by design
Your response belongs to you.
No location. No ad identifiers. No cross-app tracking. Participants see only their own sessions, and data is never sold.
Read the privacy policyIce Bath Boston
Ready to see how you settle?
Downshift is used by trained operators during supervised cold-immersion sessions.
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