Oxygen-enhanced exercise and rest have been used for top-secret military training as early as 1952. In addition, a man who could not walk up a curb was walking a mile 30 days later. I have seen it improve almost every symptom known to mankind including Parkinson's and ALS.
Imagine 25 to 150 times more oxygen than you ever had before while exercising. When I use it daily for a month I get stronger and stronger and have more stamina. Naps are no longer needed.
Using it just 15 minutes a day I wake up rested and my brain function has gotten much sharper. I rarely need to take naps anymore.
I personally used it to reduce a full minute off my 1500k race walk time at the senior games, four years older, age 75 and one minute faster.
If I am out of town for a week I sense no loss of energy.
Actually, I could take it and an O2E2 with me as they both fit into a large suitcase for air travel weighing under 50 pounds total including the suitcase.