How much oxygen, if any, do you use when you are walking on the treadmill? About 3 years ago I was asked by my doctor to start using a little oxygen while I was on the treadmill. I started on 1-2 liters and could go for about 30 minutes.. Now I am using 13 liters using liquid oxygen, because I need liquid oxygen for that high liter number, just to do 4 minutes. Apparently there is very little room left. Now what?