Safety note — deep SpO₂ responses
80–70%: Recommended training zone / green zone.
69–60%: Advanced caution zone. Stop pushing. Recover fully.
59–51%: Stop zone. No chasing. Session should end or be strongly limited.
<50%: Critical stop. Not a target. Requires strict supervision / should not be pursued.
RedPlus measures arterial oxygen saturation through SpO₂. During controlled empty-lung breath-holds, SpO₂ can fall deeply, especially in trained athletes.
Some experienced users may occasionally reach values below 70%, and rare highly trained users may go lower. However, low SpO₂ should never be treated as a competition or a target. The goal is not to reach the lowest possible number, but to create a controlled and repeatable hypoxic stimulus.
The recommended working zone is 80–70% SpO₂. Values below this range should be treated with caution, and values around 60% or lower should be considered a stop zone.
Deep hypoxia can cause light-headedness, warmth, tingling, relaxation, euphoria, confusion, loss of coordination or, in extreme cases, blackout. Because pulse oximeter readings may lag behind the actual physiological response, users should stop early, recover fully and never chase maximum depth.
RedPlus sessions should only be performed lying down or seated, never while standing, exercising, cycling, swimming, driving or operating equipment.
Users with heart, lung, cardiovascular, neurological or fainting-related conditions should seek medical advice before using RedPlus.