.
I have seen volumes of misinterpretation of wives tales +/- scienctific data, by many people, for many reasons. The article to which you referred is a perfect illustation of this. I think oxygen is not stored in muscles; but, even if it is, why do I care how much "oxygen is stored in (my) muscles."?
I think oxygen is very temporary and merely carried (by red blood cells) rather than stOred anywhere in the body. If you doubt this, go into an oxygen-free zone and see how long your "muscles' oxygen stores" last.
I'm Not Sure what your goals are, and, take no responsibility for your interpretation +/- results of application of any reply I give; but/ so, here it is anyway:
We find that continuous aerobic exercise in excess of 75 minutes begins to result in increased red blood cell creation/ volume, and also increased capillary bed depth.
Stimulative beneftis of aerobic volume should be calculated as cumulative during any rolling 24 -hour period. (Example: If training for what is likely to be a 12 hour event and volume the weekend previous is to be 14 hours, one could very safely do 8hr saturday afternoon + 6hr sunday morning, to total 14.
Some other pertanant facts:
Increases of capillary bed depth are PERMANANT.
Without stimulated regeneration, red blood cell mass begins to drop at about 5 days; after 10 days it's back to what it had been 10 days previous.
Overtraining leads to under-performance. The way to lose weight is abstenance from overeating, not overtraining.
Of course, your musculo-skeleton must facilitate and endure the event in which you're participating; so, aerobic volume should be developed as event-specifically as possible.
I can't stress enough, the usefulness of a heart rate monitor worn during all training. The way to improve performance is through appropriate amounts of event-specific training, IN THE RIGHT ZONES.