Cindy, if you know your tidal volume & breathing rate you can use this
calculator to estimate blood oxygen levels. Set the units to feet & enter altitude in feet.
If you don't change breathing rate and tidal volume, the magenta curve is pretty much a dead person.
Was gonna link to this but looks like you've done that
Although the pressure of oxygen in the atmosphere is "only" reduced by 33%, the partial pressure in the blood drops down much more. At 8000m, there's like a 97% decrease in oxygen partial pressure!
The combination of the workload calculator with the oxygen pPressure could give an "effective" workload. Obviously 97% decrease in pace is significant!
