“Palm cooling” has become a hot topic among evidence-based exercisers of late.

According to several sports teams (the San Francisco 49ers, Oakland Raiders, and Manchester United F.C) and well-known fixtures of the fitness community like Dr. Andrew Huberman, cooling your palms or the soles of your feet while you rest between sets boosts your weightlifting performance.

It purportedly does this by lowering your blood’s temperature and blocking “pain” signals to your brain, which allows you to do more reps in subsequent sets than you otherwise could. This is significant because the more reps you do, the more muscle you stand to gain and the better you’ll perform in any athletic endeavor.

Not everyone is sold, though.

According to some scientists, much of the evidence supporting palm cooling fails the smell test.

For example, in two influential studies conducted at the University of New Mexico, neither the authors nor the participants were “blind” to the study’s protocols, which makes it likely that bias colored the results.

Moreover, the researchers used imprecise methods to collect muscle activation data, which makes their interpretation of the figures hard to swallow.

In another study conducted by scientists at Stanford University, the researchers claimed that palm cooling allowed at least one participant to do as many as 466 pull-ups across 10 sets (47 per set!), a suspiciously high figure (how strict were these reps exactly?). 

In a study conducted by scientists at Cheng Shiu University, the authors reported that participants who cooled their feet between sets of bench press increased the number of reps they did set on set, despite taking all their sets to failure and resting just 3 minutes between each, a fact that defies our understanding of how fatigue affects muscle function. 

And in some oft-cited, though unreviewed and unpublished trials conducted by a cooling mitt manufacturer (conflict of interest?), athletes allegedly increased dip performance by 200%, bench press performance by 31%, and pull-up performance by 516% after 2-to-6 weeks of palm cooling between sets. 

Another reason some experts have been slow to accept palm (or sole) cooling is that not all research supports its efficacy.

For instance, in a study conducted by scientists at Galgotias University, squatters who chilled their feet between sets did the same number of reps across three sets as those who simply rested. And in a study published in the International Journal of Exercise Science, weightlifters did the same number of biceps curls whether they cooled their palms, neck, biceps, or face between sets or not. 

All of this confusion spurred scientists at Ulster University to conduct a trial of their own.

Their aim was to mimic previous research on palm cooling using more rigorous methods. That way, they’d be able to discern whether flawed methodologies and poor data handling had over-egged the results of prior research or whether palm cooling actually had merit.

They had 11 experienced weightlifters do 3 workouts 4 days apart. In each workout, the weightlifters did 4 sets of bench press with 80% of their one-rep max to failure and rested 3 minutes between sets.

During their rest periods, the weightlifters spent one minute with their hands in a cooling device. In one workout, the device cooled their palms to 50°F; in another, it cooled them to ~60°F; and in the other, it kept them at ~82°F (the “control” condition).

The results showed that palm cooling at 50°F or ~60°F didn’t affect bench press performance. It didn’t increase the number of reps the weightlifters could do set on set, improve power output, or change how active the pecs, delts, and triceps were while performing the bench press.

This is a blow to palm cooling’s credibility. And while the results of one study aren’t enough to say that palm cooling has no benefit, it pulls another leg out from under the already shaky evidence in favor of palm cooling.

It’s also worth noting that not a single study has shown palm cooling increases muscle growth. If palm cooling significantly improved your workout performance, then this probably would lead to more muscle growth over time, but no studies have shown this to be the case thus far.

In the coming months and years, I suspect we’ll hear more about the performance-boosting effects of palm cooling.

However, unless we get more convincing evidence that palm cooling is as effective as its promoters claim (one Stanford University researcher claimed it’s “equal to or substantially better than steroids” at boosting performance), it’s probably not worth indulging. 

Takeaway: While some dubious studies suggest that cooling your palms between sets allows you to do more reps per workout, high-quality research shows it does nothing to aid performance.

This article is part of our weekly Research Review series, which explores a scientific study on diet, exercise, supplementation, mindset, or lifestyle that will help you gain muscle and strength, lose fat, perform and feel better, live longer, and get and stay healthier. 

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