X-Bionic – Radiactor V1 Running Top

Turn sweat into energy that, at least, is X-Bionic’s catchline. And given the rate that I perspire wearing this Swiz sportswear could leave Croydon facing a meltdown the likes of which was last seen at Chernobyl. Even from its box-like packaging, adorned with a multitude of nods to its awards for research and development, the X-Bionic Radiactor long-sleeved top seems to be almost dripping in science.

And a quick online search for this firm’s sci-fi-styled clothing only adds further to a reputation that speaks to Swiz-army knife practicality and a desperation to put the science into sports science. X-Bionic have gone to great lengths to let the potential buyer into their laboratories and workshops showing off their scientific method with a set of seemingly sadistic videos. These videos see “average athletes” kited out in non-brand clothing and forced to run in brain-baking temperatures until they collapse. Then an endurance athlete dons X-Bionic’s clothing and cheerfully reports, thanks to this space-age clobber, he’d be happy to carry on and run at temperatures in excess of 51C.

Now, I’m running in the UK and a chance to run at temperatures in excess of 30C would be a rare and welcome opportunity most months. But still, whatever the weather, when you run you get hot. And the more energy your body expends keeping your core cool the less you have to power your legs. The X-Bionic sportswear is designed to trap sweat in microducts. That trapped sweat then absorbs excess body heat helping keep the body cooler. The shirt also has panels of these microducts built where one sweats the most, the back, chest and armpits.

When I run, I generally notice it’s my chest that feels the most warm and my back that has the most sweat, probably not helped by the fact that I wear a rucksack most days. With the X-Bionic top, my core – particularly my chest – felt a lot cooler. Conversely, my back was a lot dryer than usual. Oddly, my arms were a lot wetter than usual.


Without running with a thermometer I can’t speak with scientific certainty that my core was cooler, but I didn’t get that slightly uncomfortable flushed feeling I usually get mid-way through a run and it’s often that feeling, a sickly sense of my organs being slow-roasted, which makes me feel as if I should slow down some.

The top also boasts a clever compression system which works with the body, maintaining stability without blocking blood flow. I can attest that the top is tight, and tight in places other compression tops don’t seem to be. The range comes in at least three degrees of compression – with the one I tested the tightest. In fact, wearing it is probably the first time I’ve ever been glad for a missing six pack as, given the top’s figure-hugging styling, I’m not sure where I’d stick one. The chest in particular feels a little odd – almost as if it’s trying to take the place of a push-up bra. There’s definitely a feeling of lifting and separating.

Once I stated out I didn’t noticed the tightness at all, in fact that only thing my mind kept turning to was that cool feeling around my chest. I have in the past, usually when it’s raining, suffered from runner’s nipple. Given the tightness of the top of was particularly worried about this occurring. Thankfully, the fabric, a mix of polyester, elastane and polypropylene, didn’t seem to rub at all. It didn’t rain while tested but given that there seems to be very little give in the top I’d put even money on my nipples being safe from a good grating.



The major downside is a purely superficial one. The top looks a little odd. A mix of sparkly silver and cross hatching made me feel a little like an underdeveloped Cyberman on the run from a Timelord wielding a vicious sonic screwdriver. I don’t care greatly about what I look like when I run – my grimace-ridden face is probably enough to turn most people’s glance away alone. But there’s always the worry that Croydon’s sometimes rough-and-ready crowd will be attracted by the bright and sparkly when it would be safer to stay incognito.

For keeping cool, and good stability I give the top a thumbs up. And after a straw poll of friends and family after my test runs – if got the thumbs up for being a less sweaty and antisocial than the rest of my workout wardrobe.

But, the biggest downside would seem to be the price with the research that’s gone into the product demanding a premium. Online, I couldn’t find it cheaper than about £120. If you are tackling the Marathon des Sables in the baking heat of the Sahara the cost may probably be well worth it, but for pounding the streets of Croydon keeping cool’s might not be worth the extra heat from the bank manager.

4-hammers Price: £149
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