VO2-max is one of the key indicators of longevity. It is in essence a measure of oxygen efficiency. In a laboratory, your VO2-max can be measured accurately. Here some cheap ways of estimating your VO2-max.
Running: Measure your maximal running distance d(12min) in a 12 minute time interval. Ideally choose a 400m track circle or a flat route. Your VO2-max is now estimated by:
Cycling: Measure your maximal power W (in Watt) in a 6 minutes time interval and your body weight M in kg. This is ideally done uphill or on a home trainer. Your VO2-max is now estimated by:
Heart rate method: Measure your maximal and rest Heart Rate HR. Your VO2-max is now estmated by: