Sick of overheating mid-run? I tested a workout baselayer incorporating smart fiber, thermo-regulation technology originally developed for astronauts | Tech Radar

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Sick of overheating mid-run? I tested a workout baselayer incorporating smart fiber, thermo-regulation technology originally developed for astronauts

The Walero Active range incorporates Outlast technology

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We've tested a lot of crazy workout gear over the years, from Adidas' pressurized workout shoes to elaborate virtual coaching booths, but never anything from space.

Let me confirm that I haven't actually worn anything from outer space: this is a workout layer from premium activewear company Walero, which also makes professional-grade motorsport gear. The Walero Active temperature-regulating baselayer incorporates Outlast technology, which is a fabric system originally developed for NASA to clothe its astronauts.

The Outlast website says "the most important part of fabrics and materials with this NASA technology is the microencapsulated wax, which is usually won from rapeseed oil.

"When the temperature rises, it causes the wax in the capsules to melt. During this phase shift, the temperature cannot increase any further. Heat peaks are reduced or even prevented and as a result, sweat production decreases by up to 48%."

So the wax hardens and softens inside the fabric based on the wearer's temperature, capping it. Clever.

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While the Walero baselayers only consist of 20% Outlast technology, I was intrigued enough to try it when I was offered to test one. Given that I also test the best running shoes in addition to fitness gadgets, I'm always intrigued when I hear about performance-enhancing technical fabrics and materials in addition to smartwatches and other gadgets on my usual beat.

So, without further ado, I laced up my Saucony Ride 19s and hit the road, wearing it on as many runs as I could (in between washes) over a month.

I tested the Ben Nevis long sleeve half-zip Walero Active top, but I found it difficult to judge its results in an objective, numerical fashion. Walero claims its kit is scientifically proven to lower heart rates by 8%, and sweat production by 30%.

However, one person's sweat production and heart rate can change dramatically for all sorts of reasons, ranging from what they've eaten that day, to the weather, to their previous night's sleep. I normally test the best smartwatches against a Polar H10 heart rate monitor to obtain numerical data, but I found it difficult to deliver any meaningful comparison data on a regular workout vs. one in the top. An 8% decrease in heart rate isn't a massive change for the average runner to measure, although it could mean everything for an elite athlete. How does a mediocre but enthusiastic runner quantify this sort of thing?

Nevertheless, after running 10 kilometers in a UK heatwave, during which I would have normally worn as little clothing as possible (and certainly not a long-sleeved top) I must admit I was partially convinced. I wore a sleeveless t-shirt underneath, and hadn't needed to remove the long-sleeved top at all during the run.

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Other runs in the top, some shorter, some similar distance, were done in cooler conditions, including one in the rain. At all times, the layer stayed on, apart from one exceptionally hot day. I didn't see any historic achievements or plateau-breaking as a result of wearing it, but my runs felt strong and the top was comfortable. I didn't need to shed the layer in most hot conditions to avoid overheating, or feel like it was insufficient in cold.

At the end of the day, it's a very premium-priced (a hefty £195, around

One independent study testing the thermo-regulation property of Outlast fiber by means of thermal analysis found that the 'smart fiber' as its called, has "been certified [for] its obvious capability of temperature regulation". So the Walero top will reduce sweat and keep your body regulated with its 20% Outlast fibers woven into its construction, in theory.

In practice, for most of us, it's a fun novelty that seems ideal to wear in most conditions, and most suited to cooler changeable weather. You'll get a lot of wear out of it as it's very adaptable, but it's certainly more expensive than most baselayers. It's a cool gimmick to chat about as you queue up at the startline of your local parkrun, but whether it represents good value will depend on your budget. An amateur athlete looking to save money (most of us) won't get enough mileage out of this top to justify the expense, while a high performer with deep pockets will likely live in it due to its thermo-regulating qualities.

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Matt is Tech Radar's expert on all things fitness, wellness and wearable tech.

A former staffer at Men's Health, he holds a Master's Degree in journalism from Cardiff and has written for brands like Runner's World, Women's Health, Men's Fitness, Live Science and Fit&Well on everything fitness tech, exercise, nutrition and mental wellbeing.

Matt's a keen runner, ex-kickboxer, not averse to the odd yoga flow, and insists everyone should stretch every morning. When he’s not training or writing about health and fitness, he can be found reading doorstop-thick fantasy books with lots of fictional maps in them.

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