This Sunday, October 11, roughly 55,000 runners will take over Grant Park for the 48th Chicago Marathon — and with a record 200,000+ people applying to run this year, the fall marathon boom is very real. Whether you are on the start line in Chicago or training for your own 26.2 later this season, race week comes down to one thing: execution.
And execution, for most runners, breaks down the same way. The legs feel fine at mile 15. By mile 20, the fade starts. That is not a willpower problem — it is an oxygen problem. When your body cannot deliver enough oxygen to working muscles, endurance drops no matter how strong your training block was.
The science behind breathing easier
That is why GO² built a patented breathing device designed around a simple idea: increase oxygen uptake, and endurance follows. Peer-reviewed research conducted at Texas A&M and Houston Methodist, published in Sports Medicine and Health Science, found that GO² takes about 10 minutes off a 4-hour marathon, increases endurance by 6%, and raises VO₂ max by 4% — while lowering heart rate.
It is the only breathing device scientifically proven to increase oxygen and endurance, and it is trusted by elite endurance athletes including World Mountain Running Champion Joseph Gray, pro high-altitude climber Don Bowie, 24-time IRONMAN Ricardo Urbina, and 3-time IRONMAN champion Laurel Wassner.
How to use it on race week
- Warm up with it. Use GO² during your pre-race warm-up so your breathing pattern is dialed in before you hit the corral.
- Race with it. The device is lightweight and stays in place, so there is nothing to fumble with at mile 20.
- Keep it simple. Race week is not the time for new experiments — GO² fits into the routine you already have.
Chicago is famously one of the fastest marathon courses in the world — flat, cool, and the site of seven world records. If you lined up for a PR, do not leave your breathing to chance.