Cold Plunges: Hype vs. Reality – What the Science Says
Robert F. Kennedy Jr., the current Secretary of Health and Human Services, posted a workout video last month featuring push-ups, cycling, and a cold plunge—all performed even as wearing jeans. The video, co-starring musician Kid Rock, highlights a practice gaining traction across North America, but one increasingly scrutinized by researchers.
Cold-water bathing, once a staple in ancient Greek and Roman medicine for treating fevers, and later employed in 18th-century mental institutions as a shock therapy for depression and psychosis, is experiencing a modern resurgence. Celebrity endorsements, from Dr. Mehmet Oz’s Instagram ice bath demonstrations to athletes like LeBron James and Paula Radcliffe touting its recovery benefits, have fueled its popularity. Though, a growing body of research suggests the benefits of “cold plunging” may be overstated, and in some cases, counterproductive.
Proponents often claim cold exposure activates “brown fat,” a type of fat tissue believed to burn energy and offer metabolic advantages. Casey Means, President Trump’s nominee for surgeon general, publicly endorsed cold plunges in 2024, citing this activation. But studies indicate that most adults possess limited amounts of brown fat, diminishing the potential for significant health gains. Even research on Wim Hof, known as “The Iceman” for his extreme cold tolerance, found his brown fat activation after a cold plunge session to be “unremarkable,” according to a study utilizing fMRI and other imaging techniques. Hof himself acknowledged to The Atlantic that brown fat isn’t the primary driver of warmth in cold environments, though he maintains his breathing techniques support muscular activity that generates heat.
The practice also gained traction as a workout recovery method, popularized by marathoner Paula Radcliffe in 2002. While some studies suggest cold-water immersion can reduce muscle soreness, others demonstrate it can hinder muscle growth. A 2015 study found cold plunging after resistance training reduced muscle growth by 20 percent. This contradicts the narrative of elite athletes who routinely use ice baths post-exercise.
The combination of hot saunas and cold plunges, known as “contrast therapy,” is now commonplace in many North American wellness centers. However, research suggests the heat component may be more beneficial for muscle health and recovery. The cardiovascular and cellular benefits of heat adaptation are maximized when the core body temperature reaches approximately 101.3 degrees Fahrenheit, a threshold often bypassed when immediately followed by a cold plunge. Current trends in the NBA, for example, involve alternating between 15-minute infrared sauna sessions and three minutes of frigid water immersion, potentially negating the benefits of heat exposure.
Recent studies reinforce the advantages of heat alone for recovery. A 2017 clinical trial demonstrated that participants recovered better from exhaustive arm-cycling intervals when their arms were warmed rather than cooled. Similarly, warm water was found to speed healing and reduce soreness in subjects with laboratory-induced muscle damage, while cold-water immersion showed no benefit. Warm water promotes blood flow and activates heat-shock proteins, aiding in muscle repair, while cold water constricts blood vessels and inhibits these processes.
Even the originator of the RICE protocol (rest, ice, compression, elevation) for injury recovery has revised his recommendations, acknowledging that inhibiting inflammation can also impede healing. Research now suggests that transient inflammation is a crucial signaling mechanism for the body’s healing response and for driving improvements in strength and endurance.
The existing research on cold plunging is often limited by small sample sizes—typically 20 subjects or fewer—and a demographic skewed towards healthy, young men. Studies are also often short-term, examining the effects of only a single session. The inherent difficulty of conducting truly blind studies on cold exposure further complicates the research landscape.
A large-scale study conducted in the Netherlands, involving over 3,000 participants aged 18 to 65, revealed a surprising benefit: those who ended their daily showers with 30, 60, or 90 seconds of cold water missed approximately 30 percent fewer workdays compared to a control group. Both groups reported similar total illness days, suggesting the cold showers increased motivation to operate despite illness. Notably, many participants continued the practice voluntarily even after the initial 30-day study period ended.
Mike Tipton, a professor of extreme physiology at the University of Portsmouth, explains the psychological effects of cold-water immersion. “That sudden fall in skin temperature releases quite a lot of stress hormones, and ends up releasing serotonin. So you gain a feel-good factor,” he said. “It’s the thing that makes you feel alive.” The mood-boosting effects of cold exposure appear to be among its most consistent benefits.
Bill Gifford, author of the forthcoming book Hotwired: How The Hidden Power of Heat Makes Us Stronger, recounts his own experience at a sauna gathering near Lake Superior, where he initially resisted the cold plunge but ultimately found it appealing when shared with others. He realized the practice was less about physical optimization and more about altering one’s mental state—a modern echo of the ancient “bain de surprise.”