When you think of nitrogen gas, it’s unlikely that you imagine it being used in a pair of running shoes. More commonly, it’s a gas associated with industry, such as to preserve the freshness of packaged foods, in the manufacture of light bulbs. or to inflate racing car and aircraft tires.
But now, sports shoe brand inov-8 has found a new use for the inert gas – to give runners more bounce. The company, which was the first to use graphene in running footwear, has launched the Trailfly Ultra G 280 shoe with nitrogen-infused midsole foam, which it claims gives an improved ride.
But why use nitrogen in running shoes?
inov-8 isn't the only company to use nitrogen-infused foam in its shoes (Brooks used the stuff in its Aurora-BL road shoe), but why is it important? Air is already composed of 78.08% nitrogen (with the remainder being 20.95% oxygen and several other gases at low percentages), so we asked inov-8 why it has chosen to infuse nitrogen into the foam.
"Using denser gases like nitrogen allows our shoes to absorb energy upon impact without releasing the air," said a spokesperson for the company. "When infused in our midsole, nitrogen provides unique cushioning benefits, as well as keeping the final compound (midsole) lightweight."
To prove the trampoline-feel bounce, inov-8 reveal that testing shows the Flyspeed foam gives back 65% to 68% of the energy put in, compared to a standard foam midsole, which gives back 45% to 48%.
The new shoe also has rubber enhanced by graphene, which is 200 times stronger than steel. The brand claims the graphene soles offer the world’s toughest grip, and a “clever underfoot flexing technology that allows runners to feel more connected to the trail”.
Anything more to know about nitrogen infused running shoes?
The new inov-8 nitrogen-infused foam is called Flyspeed. Wayne Edy, founder of inov-8, which is based in the UK’s Lake District, says: “The nitrogen foam we’ve created gives an amazingly lighter, softer ride for those runners looking for that.
“It debuts on our new Trailfly Ultra G 280 shoes, which we can’t wait to get on the feet of trail and ultramarathon runners. It has great levels cushioning, while at the same time delivering incredible bounce and a feeling of being connected to the trail.”
The Trailfly Ultra G 280 is designed for trail running and ultramarathon running on hard-packed trails. Each shoe weighs 280g (average across size curve), with a heel-to-toe drop is 8mm and lug depth of 4mm. The shoe retails at £165 / $185 / €190.
What do the Trailfly Ultra G 280 testers say?
The Trailfly Ultra G 280 have been tested by a number of inov-8 athletes, who have competed in – and, in some cases, won – races ranging from 5km to 350km.
Top Spanish trail runner Abel Carretero said of the shoes: “The comfort is extremely good for long distances and the bounce is so great you feel like you’re flying. It feels a bit like cheating!”
An Advnture runner will be reporting on the Trailfly Ultra G 280 in a review once we’ve given the shoes a try. We’re guessing the results will depend on whether you like lots of bounce in your trail running footwear, or if you prefer to have more underfoot feel and contact with the ground.
It will be interesting to see whether the trail running shoe will feel lighter and bouncier than a sole filled with nitrogen, rather than air.
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Fiona Russell is a widely published adventure journalist and blogger, who is better known as Fiona Outdoors. She is based in Scotland and is an all-round outdoors enthusiast with favourite activities including trail running, mountain walking, mountain biking, road cycling, triathlon and skiing, both downhill and back country. Her target for 2021 is to finish the final nine summits in her first round of all 282 Munros, the Scottish mountains of more than 3,000ft high. Aside from being outdoors, Fiona's biggest aim is to inspire others to enjoy the great outdoors, especially through her writing. She is also rarely seen without a running skort! Find out more at Fiona Outdoors.