Cold-water immersion (CWI) has gained significant popularity among athletes and the general population in recent years. Enthusiasts claim numerous health benefits, from reducing stress to improving sleep quality and even decreasing sick day absences. Despite its rising trend, a recent systematic review and meta-analysis reveal that the benefits of CWI may be more immediate and short-term, with more research needed to understand its long-term effects and practical applications.
The review included 11 studies, seven of which were of moderate quality and four of high quality. Researchers examined these studies to assess the effectiveness of CWI. Notably, one trial found a 29% reduction in sickness absences among participants who engaged in cold plunging. While the review highlights potential benefits, such as enhanced sleep, improved quality of life, and reduced stress, it also underscores the need for more extensive research to determine lasting impacts.
“Right now, cold plunging seems to have more immediate, short-term benefits. People report feeling more awake, less anxious, and even euphoric right after a plunge—likely due to the rush of endorphins and adrenaline.”— David Merrill, MD, PhD
The ideal water temperature for CWI appears to be between 10 and 15 degrees Celsius. Experts advise submerging only up to neck level to avoid adverse health consequences linked with dunking one's head. Short sessions are beneficial, but research suggests an optimal duration of approximately 12 minutes for those experienced in CWI.
“Firstly, the ideal water temperature appears to be between 10 and 15 degrees Celsius. While many practitioners use water considerably colder, the additional physiological and/or psychological benefits of this have yet to be demonstrated empirically. Secondly, it is advisable to submerge only up to neck level, as dunking one’s head has been associated with some adverse health consequences, and may even undermine some of the positive effects of CWI. Finally, while short sessions are of benefit, research has indicated an optimal CWI duration of approximately 12 minutes for experienced practitioners,” Colbert explained.— Dylan Colbert, PhD
The review's authors used ten databases to identify eligible randomized controlled trials, aiming to understand CWI's physical and potential additional benefits. The findings suggest that while CWI remains popular among athletes for recovery purposes, its long-term mental health benefits remain uncertain.
“The question is whether those effects translate into long-term improvements in mood and resilience. We need studies that track people over time to see if regular cold exposure has lasting mental health benefits, especially for those with clinical depression or anxiety,” he added.— David Merrill, MD, PhD
The body's response to cold immersion mimics its reaction to stressors, triggering an immune response that temporarily increases inflammation. This mechanism is similar to how exercise causes short-term muscle damage before leading to strength gains. Regular use of CWI may help reduce overall inflammation and support recovery.
“The body perceives cold as a stressor, activating an immune response that temporarily increases inflammation, much like how exercise causes short-term muscle damage before leading to strength gains. Over time, regular use of cold-water immersion may help reduce overall inflammation and support recovery, which is why it remains popular among athletes despite the initial inflammatory response.”— Tara Cain, study author
Despite its growing popularity, experts urge caution due to the lack of comprehensive research on who benefits most from CWI and what constitutes the ideal approach. The review emphasizes the need for long-term studies involving diverse populations to better understand CWI's lasting effects.
“Right now, there isn’t enough high-quality research to say exactly who benefits most or what the ideal approach is to cold-water immersion. More long-term studies, among more diverse populations, are needed to understand its lasting effects and practical applications,” Cain noted.— Tara Cain
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