RCT is the boundary between high intensity activity and severe intensity exertion. Under normal conditions the bodies drive to breathe is based on carbon dioxide levels in the blood. When RCT is reached, the bodies drive to breathe is driven by lactate levels. This causes very heavy respiration and signifies a transition point in which fatigue starts to overcome the body’s ability to sustain exercise intensity. TrainingMask® increases RCT which allows the body to generate incrementally more effort before the point of exhaustion is reached.