Snippet: Is Freshwater or Saltwater More Effective for CWI?

Cold water immersion (CWI) is a growing recovery method used by athletes and wellness seekers. We explored the ins and outs of this in a previous article but what I have been curious about is does the environment, freshwater (bath, plunges) or saltwater (sea), influence the effects?

Freshwater

Cold baths and tubs allow for consistent temperature and duration, a more controlled environment. 

Most recovery studies on CWI focus on freshwater immersion, typically between 10-15°C, with the research showing this can reduce delayed onset muscle soreness (DOMS) after high-intensity exercise (Hohenauer et al., 2015).

The predictability of freshwater environments may allow users to be more precise, warm up easily, and ultimately offer more convenience if you’re using a tub or bath at home. 

Having that structure enables you to utilise information from studies such as a review that found 12-minute immersions at 11°C reduced perceived soreness (Claudino et al., 2024). Implementing specific immersion times and temperatures may be trickier in the sea.

Saltwater 

UK sea swimmers often report greater mood improvements and a stronger sense of connection to nature. Some researchers suggest saltwater’s conductivity may increase heat transfer, but conclusive trials confirming this are lacking.

The biggest differentiator is the increase of variables the sea introduces: wind chill, currents, and often lower temperatures. These can intensify the cold shock response (Tipton, 2016), making safety a bigger consideration. Repeated exposure can improve tolerance, but beginners should approach cautiously.

Qualitative studies in the UK describe psychological benefits from both sea and loch swimming, including improved mood and resilience (Willis et al., 2022). ZOE Health data also found regular sea swimmers showed lower inflammation markers, though the causality of this is unclear.

Recovery, Inflammation, and Immunity

CWI helps reduce inflammation by constricting blood vessels and slowing metabolism. While most studies use freshwater, limited evidence suggests similar effects from saltwater. There is research to suggest that repeated exposure improves immune markers (Knechtle et al., 2020).

Regular swimmers show reduced sympathetic stress responses and inflammation compared to first-time dippers, regardless of water type (Tipton et al., 2017).

So Which Is Better?

Unfortunately, there is no strong evidence that one is better than the other. 

Both offer overlapping physiological and psychological benefits. It comes down to a personal choice based on safety, accessibility, and preference.

• Freshwater is likely to be better for consistency and control.

• Whereas saltwater is a wilder, more exposed and increased sensory experience.

Regardless, if you’re starting out, begin gradually, prioritise safety, and build cold exposure tolerance over time.

If you want to find out more about CWI, read our detailed article here.

References (APA)

1. Claudino, J. G., et al. (2024). Cold-water immersion vs percussion massage on post-exercise recovery: a randomized controlled trial. Frontiers in Physiology, 15, 1432009. https://doi.org/10.3389/fphys.2024.1432009

2. Hohenauer, E., et al. (2015). The effect of post-exercise cryotherapy on recovery characteristics: a systematic review and meta-analysis. PLOS ONE, 10(9), e0139028. https://doi.org/10.1371/journal.pone.0139028

3. Knechtle, B., et al. (2020). Effects of cold water exposure on the immune system, inflammation, and oxidative stress: A systematic review. International Journal of Environmental Research and Public Health, 17(21), 7873. https://doi.org/10.3390/ijerph17217873

4. Radler, C., et al. (2023). Brain activity after short-term cold water immersion: A functional MRI study. Biology, 12(2), 211. https://doi.org/10.3390/biology12020211

5. Tipton, M. J. (2016). The initial responses to cold-water immersion in man. Clinical Autonomic Research, 26(6), 385-398. https://doi.org/10.1007/s10286-016-0375-9

6. Tipton, M. J., et al. (2017). Habituation of the initial responses to cold water immersion in humans: A review. Physiology News, (107), 26–30.

7. Willis, C., et al. (2022). Wild swimming, health and wellbeing: A qualitative exploration. Sustainability, 14(10), 6364. https://doi.org/10.3390/su14106364