Everyone from high-level athletes to your favorite health influencers seems to love cold plunges. However, a new study pours some cold water on this idea. Not only do they hamper blood flow and recovery, but they even reduce muscle gains.

“It looks like it’s not a great idea,” says Milan Betz, a doctoral student at Maastricht University in the Netherlands, for the Washington Post. Those cold plunges may have a pretty big downside.

The science was never really clear on this one, despite what TikTok stars clad in compression shorts may claim. However, this is the first study to connect the dots. Betz and colleagues recruited 12 healthy young men and asked them to undergo a workout session for lower-body resistance. Then, they had each participant dunk one leg in 8°C (46°F) water — cold enough to make most people gasp — while the other leg bathed in 30°C (86°F) water, which served as a control.

For 20 minutes, they sat like human yin-yangs: one leg frozen, the other warm. Then, they drank a specially formulated recovery beverage loaded with amino acids and a traceable version of phenylalanine, a protein building block. This let researchers track how much of the ingested protein ended up where it mattered most: inside muscle fibers.

It’s an unusual but very creative approach because it uses each participant as both the control and the experiment.

To watch blood flow in real-time, the researchers used contrast-enhanced ultrasound. They measured blood volume immediately after immersion and again at one and three hours post-drink. The results were stark.

The cold-immersed leg had much lower blood flow — 1.24 versus 3.13 intensity units, a key metric for perfusion — and this difference persisted for hours. The chilled muscles incorporated about one-third less amino acids than the warmed leg.

“Cold-water immersion during post-exercise recovery greatly reduces muscle microvascular perfusion and blunts post-prandial amino acid incorporation in muscle,” the study concludes.

Ice is not nice (to your muscles)

This study doesn’t stand alone. It echoes earlier findings from Australia, where men who cold-plunged after every strength session for three months ended up with smaller, weaker muscles than those who didn’t. In 2024, a review titled “Throwing Cold Water on Muscle Growth” summed it up bluntly: cold plunges “attenuate hypertrophic changes.” In other words, it weakens or reduces muscle growth.

The suspected mechanism has always been vasoconstriction — blood vessels tightening in response to cold, throttling nutrient delivery. Betz’s study is the first to capture this process in action with its clever design.

Still, like all good science, this study leaves room for nuance.

The sample was small. Only young men were studied. And immersion occurred immediately after exercise — a common but not universal practice. Timing may matter and so might immersion length, or how much of your body is submerged. More large-scale research is needed if we want to establish the definitive conclusion on cold plunges.

This study also didn’t examine mental benefits and perception of recovery. Many people cold plunge to boost mood, reduce stress, or build psychological resilience. Betz doesn’t dispute that. If you find comfort in the chill, “there’s no reason to change your mind,” he said. But if you’re all about the gains (lifting for strength or size), this study suggests caution. The blunted blood flow from cold immersion doesn’t just feel uncomfortable — it may sabotage your progress.

So, next time you’re tempted to plunge, remember what’s at stake. A little soreness might just be the price of growth.

The study “Post-Exercise Cooling Lowers Skeletal Muscle Microvascular Perfusion and Blunts Amino Acid Incorporation into Muscle Tissue in Active Young Adults” has been published in the journal Medicine & Science in Sports & Exercise.