This past weekend, I was feeling nearly back to normal after surgery, and I was able to get out for a ride after a month of inactivity. I got out the pulse oximeter and went out on Sherman Road. I went West from Bass Lake Road and went hard up each hill. I hit the first little hill, and went at what I thought was a very hard pace. I stopped at the top and measured the O2 saturation--it barely budged from 98%. I wasn't really breathing hard, but I would have gauged the effort as "hard" based on my power output.
The second hill is much steeper, but it's pretty short. I drilled it so I was way anaerobic. I had the feeling of heaviness creep into my legs and shoulders and forearms. I stopped at the top and was gasping for air when I measured my blood's O2 saturation. Some O2 meters, apparently the one I have included, regard saturation below 92% as an error, so it didn't display anything until I recovered a little bit. That was probably one of the more intense efforts I've done on a bike.
I repeated the effort on the third hill and after that I was completely fried. I pedaled squares for the rest of the ride. I'm wondering what will happen if I do short sessions like that instead of the traditional longer tempo rides and intervals.
It really would be great to have the oxygen saturation statistic along with power output, heart rate, etc... The finger tip clip-on O2 meter is usable but very limited. There's still no "sports" O2 meter--the products that are on the market are for medical monitoring of people who are in bed. I am getting back to that project for this winter.