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Don’t Be a Mouth Breather

Peter Sagan and the new nasal dilating 100% SPEEDCRAFT AIR

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The term “mouth-breather” is basically a ruder way to call someone dumb, but it pretty accurately describes us all on the bike. When the pace gets anywhere beyond “chatting” tempo, mouths open in our quest for more air. According to the team at AC Systems, this makes cyclists mouth-breathers both literally and figuratively. Let us explain.

This story about Peter Sagan and 100% Speedcraft AIR glasses first appeared in issue 74 of PELOTON Magazine, to get issue 74 or any of our back issues head to

Ben Edwards
Hero Image: Sunada
Other Images: James Startt

There is a lot of research about the benefits of breathing through your nose versus through your mouth. There is the obvious—your nose filters out more dust and contaminants—to the not so obvious—nasal breathing actually aligns the temperature and humidity of the air you breathe to levels your lungs can better assimilate. But discoveries spearheaded by the Karolinska Institute in Stockholm, Sweden, have proven even more startling; and it’s these discoveries that AC Systems and 100% are really excited about and have created Speedcraft AIR nasal-dilating sunglasses to exploit.

It turns out that your nasal cavity creates nitric oxide, or NO. There are a few theories as to why your nose does this, but it’s what the NO does that really got AC Systems excited. NO is a vasodilator, just like Viagra (yup, that Viagra) and Salbutamol (yup, Froome’s Salbutamol), which open your airways and blood vessels. NO also helps keep your blood’s chemistry in check, along with carbon dioxide. If you start panting through your mouth, your blood chemistry goes haywire and fight-or-flight panic sets in. That’s why breathing into a paper bag is reported to help hyperventilation—rebreathing carbon dioxide helps reestablish proper blood chemistry. Nose-breathing also happens to reduce the amount of CO2 you lose when exhaling, so between NO and CO2, there are a lot of checks in the “pro” column for nasal breathing.

Watch our video testing the 100% Speedcraft AIR right here.

Of course, the big “con” is simply air volume. You can’t get enough air through your nasal passages once your aerobic load increases beyond chatting mode. This is where products like Breathe Right strips and The Turbine come in—they are nasal dilators, designed to widen those passages and increase the volume of air you can move. AC Systems felt they could do it better by integrating a nasal dilator into the optics athletes already wear. They started in motocross, where it’s not uncommon for professional racers’ heart rates to average 200 bpm for an entire event. Motocross is very much an endurance sport. Now, partnering with 100%, AC Systems has created an adjustable nasal dilator that integrates, almost seamlessly, with a pair of 100% Speedcraft sunglasses.

Three-time world champion Peter Sagan first sported the new glasses, called 100% Speedcraft AIR , at the Tour Down Under. The glasses have long arms that travel down the sides of the nose; and at the end of those arms are powerful magnets. Before putting the glasses on, and before starting to sweat, small stickers—like Band-Aids—are fixed to the side of the nose. The magnets from the glasses snap onto metal discs in those stickers and then a small dial at the top of the glasses adjusts the arms in or out, allowing riders to customize the level of nasal dilation they get.

Both Speedcraft and AC Systems pointed to Sagan’s stage 4 victory, atop the climb to Uraidla, where he was the fastest sprinter left, as evidence that the glasses help aerobic performance. Sorry, but that’s not evidence. That’s Peter being Peter. He’s always the last sprinter left on a hill. Now, if André Greipel wore them and got over that hill, we’d be more impressed.

Clearly, we had questions about these claims, so we chatted with Jim Castillo from AC Systems about the science around nose breathing, nasal dilation and the new glasses. It was Castillo who turned us onto study after study about the benefits of nose breathing, and helped us put the technology into the context of high-demand aerobic sport. Once athletes go anaerobic, are they breathing out of their nose? We think not. While there may be some who dissect Sagan’s Tour Down Under race video and see a mouth closed on the limit, it’s inconclusive to us. We wondered about the benefits long before it comes down to those make-or-break moments. Could we nose-breathe through a long gravel race? What would our heart rate do at levels below FTP (functional threshold power) just nose-breathing? Would we be fresher, with better blood chemistry, when the race does turn into anaerobic fight or flight? In short, is this snake oil, or does the science hold up and the technology work? We began to devise a test protocol to find out.

The initial impression a rider gets from the glasses is incredible—much more dilation than a Breathe Right strip. It’s as if your nose has been stuffed up your entire life and you just never noticed before. But on high-wattage, anaerobic efforts, our test rider quickly reported there was no way he could just nose-breathe, even with Speedcraft AIR fully open. Maybe Sagan can and we’ll put that next to wheelies and winning Flanders on the long list of things he can do that we can’t. We decided to test at 80 percent of FTP for multiple efforts and see how our heart rate reacted with and without the 100% Speedcraft AIR. Over 14 days and eight rides consisting of five, five-minute efforts on a trainer in Erg mode at 250 watts, we alternated each ride between nose-breathing with the glasses and mouth-breathing as we normally would without the glasses. The results after these 40 efforts were surprising, conclusive and will forever change the way we approach competitive cycling.

Here are the disclaimers. We’re not scientists, our sample group was one, our proctor was also the subject and 100% advertises in our magazine. This is the experience of one rider, but it’s worth noting for starters that the testing protocol—repeated five-minute efforts at 250 watts, with three minutes rest at 130 watts in between—was not even possible nose-breathing without the Speedcraft AIR. Our test rider simply could not breathe the air volume necessary to get through the efforts. Mouth-breathing, as we normally would for five, five-minute, 250-watt efforts on four trainer rides, our heart rate averaged 163.1 bpm. With the glasses and nose-breathing exclusively—warm up, intervals, recovery and cool down—the four rides of the exact same workout delivered an average heart rate during the 20 efforts that was 5.6 bmp lower, just 157.5 bpm. We looked at recovery too. Average heart rate two minutes after each effort was 6.3 bpm lower using the Speedcraft Air: 142.9 to 149.2. What was equally encouraging was the perceived effort: nose-breathing just felt easier, we felt calmer and we began to dread the trainer session when we were scheduled to mouth-breathe.

To say we were skeptical of the claims made by AC Systems would be an understatement. But after eight trainer rides of the identical workout, with and without the 100% Speedcraft AIR , the results speak for themselves. Nose-breathing and the gases it adds to the atmospheric air you breathe allowed our aerobic system to work more efficiently at 80 percent of our FTP. The Speedcraft AIR and the AC Systems nasal dilator simply make nose-breathing possible. Even though we were unable to take nose-breathing to the limit with Speedcraft AIR—and we are skeptical that it is even possible—the benefits of nose-breathing as you sit in the peloton during a long day, or just roll along solo saving your energy for a big climb, are undeniable for our test rider. On any ride where we know we’ll be pushed to the edge eventually, we want the Speedcraft AIR’s help to nose-breathe for as long as possible and keep our blood chemistry sound and vascular system and airways dilated, so when we do mouth-breathe our way to the limit, we have a lot more in the tank. We’re all mouth-breathers eventually, but we don’t have to be “mouth-breathers” about it.

Testing Notes
8 separate rides
5 efforts per ride
11-minute warm-up
5-minute efforts at 250 watts
40 total efforts
Rides alternated with and without Speedcraft AIR

RESULTS: Nose breathing with Speedcraft AIR reduced heart rate by 5.6 bpm during efforts. Reduced heart rate by 6.3 bpm 2 minutes after efforts.

PRODUCTS: Trainer Road software, Cyclops Hammer trainer, Wahoo Tickr Fit heart-rate monitor.

NOSE-BREATHING RIDE NOTES: Your nose will run at first—a lot! A few rides in, it stops as your nasal passages adjust. The nose stickers stay put even when you’re a sweaty mess, but sunscreen will dislodge them. Screen up after you stick them on. You’ll need traditional sunglasses if you don’t want to nosebrea the during a casual ride. Speedcraft AIR glasses have no traditional rubber nose gripper.

37g; $325 (with 20 nose stickers, $15 for 20 additional nose stickers);