I had a class all day today, so I didn’t have time to go skiing, but I was able to squeeze in a short ride in the evening. I figured it would be a good time to do an Aerobic Endurance Test.

An Aerobic Endurance Test tests your capacity at your aerobic threshold, a pace you can hold for hours. It’s defined by the point at which you body starts burning carbs instead of fat. You should be able to breathe through your nose and talk fairly easily.

To do the test you need a power meter and a heart rate monitor. After a warm up, you give your best guess of your aerobic threshold and then try to hold it (focusing on power) for one hour. If your heart rate drifts more than 5% during the hour then you guessed wrong and need to do it again. If your heart rate stays within 5% then you know you did it correctly.

The uphill athlete book and podcast both have good descriptions of this test and break it down really well.

My class ended at 5 and so I didn’t have a lot of time to get out before the sun set, so I put on my lights and got out the door at around 5:30. I shortened the 15 minute warm up to just 8 and then started the test.

It was my first time doing one of these tests, and I’m happy with how it went. I don’t have something concrete to compare it to, but I think that my aerobic threshold is the highest it has ever been. I averaged right around 250 watts for the 1 hour and my heart rate only drifted 2-3%.

According to the Uphill Athlete, if your Aerobic and Anaerobic Threshold’s are more than 10% apart then you need to do more aerobic (zone 2) work. I haven’t done an anaerobic test in a while, but my guess is that they’re closer to 30% apart right now, so I think I’ll keep chugging away with zone 2 skiing for a couple more months.

I’d be surprised if I ever get it to 10% this season, but maybe at some point in my career. That’s how people like Keegan Swenson race so strong, for so long. They have an incredibly high aerobic capacity.

What’s great about focusing on zone 2 is that it makes riding so fun. If you can go super fast all of the time because you build such a strong aerobic capacity, then racing and training becomes more fun because you’re always motoring around, and it’s not that fatiguing. You can do big days in zone 2, and do it quickly, and it’s probably the most effective way to get fast.