[sebastien murat]

The reason I suggested hyperventilation is because probably few amongst us have the drive to do max breath-holds without hyperventilation. It simply makes it easier. However, for those with a willfull will and who can push it without hyperventilation greater rewards would be achieved by not blowing off CO2 as that promotes even greater O2 desaturation and in my experience a better tolerance to low oxygen pressures (PaO2). PaO2 is the important factor has this is what keeps you conscious not SaO2; although both are intimately related.

The aim of "living high-training low" is to stimulate red blood cell production. This in iteslf increases the body's, i.e., blood, O2 carrying-capacity and CO2 buffering ability, both of which will prolong absolute breath-hold duration and possibly (?), hypoxic/hypercapnic tolerance.

Cheers,
Seb