Some Basic Guidelines

Some basic guidelines, backed by the best data and studies we have about how to optimize cold water immersion. These are my personal conclusions of how I use CWI after reading through the research and building a reasonable protocol of when and how to use CWI for myself.

• Wait an hour or two after strength training

• Cold after cardio is okay, and likely beneficial

• Listen to your body, don't push yourself too far or too hard at first, as with any exercise or body stressor

• Learn breathing techniques to manage the initial shock, Wim Hof is the go to 'authority' on this topic

• 10-14C is a good starting temperature for a 5-10 minute immersion

If you like watching video format overviews, check this out. It does not cover all of the areas of research exhaustively, but is a good overview of the topics it does cover: Rhonda Patrick: Cold-Water Immersion and Cryotherapy: Neuroendocrine and Fat Browning Effects

How Cold

Effects seem to start around 16C, with the some of the most pronounced physiological effects occurring around 10C in some studies. One study used 15.3C for 30 minutes after cycling training 4 times per week over the course of 39 days. Result: [8] The cyclists using cold water experienced 4.4% increase in average sprint power, 3% enhancement in repeat cycling performance, and a 2.7% increased power over the 39 day training period. Not many studies use water colder than 14C with any significant exposure time. Some studies do use nearly freezing (35.6F, 2C) water but for very short exposure times (and even those studies saw hormonal response!)

How long

Some studies have done 14C for an hour, but the research indicates you don't have to go this long to start produce significant effects in the body. As shown [8] the times do not have to be extreme to start seeing effects. 30 minutes is a long time for most people and there is correlation between temperature and magnitude of effect, to a point.

[5] Another study demonstrated measurable and significant effects around 10-15C with only 3 minute immersion times.

Some effects do seem to be optimized with long and relatively cold (14C) exposures. The short answer is, even 5-10 minutes is enough, especially for frequent use.

After Resistance Training

Evidence suggests that post-exercise CWI attenuates (reduces) the growth of muscle fiber when used following resistance training, however it did not seem to have an impact on overall lean mass.

• [1] Observed lower fat mass in the CWI group.

• [1] Did not observe any impact on maximal strength.

• General Recommendation: Do not use CWI immediately after strength training as a recovery modality.

[1] "This study adds to existing evidence that post-exercise cold water immersion attenuates muscle fiber growth with resistance training, which is potentially mediated by attenuated post-exercise increases in markers of skeletal muscle anabolism coupled with increased catabolism and suggests that blunted muscle fiber growth with cold water immersion does not necessarily translate to impaired strength development."

[2] Wrist-flexor thicknesses of the experimental arms increased after training in both groups, but the extent of each increase was significantly less in the cooled group compared with the noncooled group. Maximal muscle strength and brachial-artery diameter did not increase in the cooled group, while they increased in the noncooled group. Local muscle endurance increased in both groups, but the increase in the cooled group tended to be lower compared to the noncooled group. Regular post-exercise cold application to muscles might attenuate muscular and vascular adaptations to resistance training.

[3] Conclusions: A recovery placebo administered after an acute high-intensity interval training session is superior in the recovery of muscle strength over 48 h as compared with TWI [editor: Thermoneutral Water Immersion, e.g. the control] and is as effective as CWI. This can be attributed to improved ratings of readiness for exercise, pain, and vigor, suggesting that the commonly hypothesized physiological benefits surrounding CWI are at least partly placebo related.

Metabolism and Inflammation

[4] One of the more cited studies observes a number of interesting and potentially beneficial effects, with the effects being the most dramatic at 14C water. The immersion time was 1 hour. More on immersion time later.

I am highlighting this study to show the correlation between temperature and effect as well as the very reproducible Noradrenaline and dopamine production cold imparts. Some of the most interesting effects occur only below 16C (14C in this study).

[6] Noradrenaline release is shown to reduce inflammation and help activate the immune system.

Rhonda Patrick -- Cold Shocking the Body

Rhonda Patrick is more qualified than I am to comment on the research. Here is her Thousand Mile High Summary:

1. Cold shock shows some interesting promise for helping diseases of neurodegeneration through a special cold shock protein known as RBM3… will we be taking people and putting them through super traumatic freezing temperatures in the future to prevent Alzheimer's? I don't know, but the fact that this neuroprotective, www.foundmyfitness.comsynapse fixing effect happens in mice is a very good sign and hints at some really profound things we may find out in the future are applicable to humans as well.

2. Norepinephrine, which can go up a huge amount from a variety of different cold stressors, has some pretty interesting properties and is a very versatile neurotransmitter and hormone! We need it for vasoconstriction, as part of our body's dynamic response to cold, but it is also anti­infammatory. For this reason it may have special relevance for diseases of inflammation, like arthritis, as well as mood and even depression.

3. Giving yourself short bouts of intense cold stress may be applicable if you have some degree of chronic pain, because of the analgesic effect, which may also be partly mediated by… you guessed it… norepinephrine.

4. There may be some truth to winter swimming improving immune function in regular practitioners.

5. In contrast to old dogma, adult humans have brown fat and exposure to cold increases it. Brown fat generally decreases as we get older, especially if we're obese. Having more of it, however, is associated with trending towards a lower body fat percentage, and, finally, the amount of brown fat is directly affected by our exposure to cold. Cold­water immersion can definitely increase brown fat, but so can cold air, which means whole body cryotherapy is probably also effective for this purpose.

6. Using cryotherapy and cold­water immersion in the context of exercise is sort of complicated! You can definitely undermine your gains in the context of resistance training ​if ​you're doing cold­water immersion immediately after training. In other contexts, however, there may be improvements as well. We still have some unanswered and very interesting questions surrounding this. I'm hopeful that the more deleterious effects will turn out to be mostly constrained to the hour long window of time immediately after training, but I'm not really sure. We need more studies to say for certain!

7. When comparing whole­body cryotherapy and cold­water immersion, they are are probably pretty similar… at least in many of their hormonal responses. One key point of difference is that it is possible to stay in cold water for a longer period of time than it is to stay in a cryotherapy chamber, which could put you in danger of local tissue damage, such as frostbite. Do what strikes your fancy until better evidence emerges.

Conclusion

There is still a lot of ongoing research and understanding to be done regarding cold water immersion. The overwhelming direction of the impact of cold water immersion is a positive impact on one's health. Obviously, there are no silver bullets or concrete answers in health science like this. Give it a try and see how you feel!