What’s the relationship between vo2max and cardiorespiratory exercise?

VO2 Max is the most accuratemeasure of cardio-respiratory fitness. It measures the maximum amount of oxygen that the body can use in one minute per kilogram of body weight (mL/kg/min). During exercise, the heart rate responds by increasing, as does the delivery of oxygen to the body.

They probably don't understand either 1. what the nightmare is about or 2. his anxiety and stress