Cold plunging: building up safely in 4 weeks

Short answer: start with 15 to 30 seconds in cold tap water and build up over four weeks to 2 to 3 minutes. Step in while exhaling, keep your breathing low and long, and get out of the water immediately if you start shivering or your limbs tingle. You do not need more than cold tap water (8 to 15 °C); ice is a progression for advanced practitioners. Below is the full schedule, the breathing technique and the contrast protocol with the sauna.

Your cold plunge tub in brief

The Ice Tub Mini (1 person, Ø 102 x H 111 cm, 350 litres) has an insulated fibreglass shell with a wooden surround, a ball valve for filling and draining, and an insulating cover. Filling is done with a garden hose; the cover keeps the water cool, clean and free of leaves. Preferably place the tub a few steps from the sauna, on a tile or deck panel to avoid muddy feet.

The 4-week schedule

Get out of the water immediately if you shiver uncontrollably, if your hands or feet tingle, or if you feel light-headed. You adjust to cold quickly: what feels intense in week 1 is routine by week 4.

The breathing technique

The cold shock of the first seconds is a reflex: gasping for air and breathing fast. That reflex can be controlled:

1. Take three to four calm, deep breaths before getting in.
2. Step in while exhaling slowly; that dampens the startle response.
3. Then breathe out consciously, low and long, as if blowing through a straw.
4. After 20 to 30 seconds the reflex subsides and the water becomes "still". That moment is what you come for.

The sauna contrast protocol

1. A sauna round of 8 to 15 minutes (see sauna temperature and loyly).
2. Step outside for 1 to 2 minutes; the worst of the sweat will have gone by then.
3. Shower briefly and then get into the cold plunge tub for 30 to 90 seconds, shoulders under if you can.
4. Warm up naturally: dry off, get dressed, move around gently. Do not shower hot straight away; the body warms itself.
5. Rest for at least 10 minutes before the next round.

What about ice?

If you add ice or cool actively with a chiller, the water drops towards 0 to 5 °C and this is called an ice bath. That increases the intensity considerably, but not necessarily the effect: the refreshing, restorative feeling also occurs fully at tap water temperature. Complete the schedule above first before moving to genuinely ice-cold water, and keep the sessions shorter once you do.

Keeping the water cold and clean

• Always keep the cover on: it keeps out solar heating, leaves and insects and keeps the water cold for longer.
• Change the water regularly: with 350 litres, changing the water via the ball valve is the simplest route to clean water; more often with daily use than with occasional use. Cold water slows bacterial growth, but does not replace changing the water.
• Shower briefly before plunging, especially straight after the sauna: sweat is the biggest contaminant of small volumes of cold water.
• Winter: you can keep using it; remove any layer of ice before getting in. If you will not use the tub for a longer period during frost, drain it completely via the ball valve.

Common mistakes

• Staying in too long to prove you can: the effect happens in the first minutes, the risk in the minutes after that.
• Diving under with your head in ice-cold water: do not do this; keep your head above water.
• Plunging alone with no one nearby: especially avoid this as a beginner.
• Showering hot straight afterwards: do not skip the natural warm-up.