Aerobic fitness is generally measured quantitatively using one measurement: VO2(max) [1]. This is deemed sufficient for anyone who is a casual athlete or below; you would need more metrics for, say, an olympic athlete or an air force pilot. VO2 is measured as 15*(fraction of resting heart-rate), or
Where HR(rest) is your resting heart-rate, such as 15-20 minutes after you've woken up, before you've started any strenuous exercise. To get to your HR(max), the most common, and easiest, way is to use a treadmill that has a heart-rate monitoring device.
The treadmill is the best device to use for this because it keeps you at a consistent pace. The general method (off the top of my head) is
- Start off at a pace of 1.5-2mph and 0% incline for 2-3 minutes
- After given time, measure heart-rate
- Increase incline by 1%
- Walk at current pace and incline for 2-3min
- Measure HR
- Increase pace by 1mph
- Walk at current pace and incline for 2-3min
- Measure HR
- Repeat until you either have to stop or your HR plateaus (be careful not to go above 5% incline - just increase pace)
The idea is to let your heart adjust your heart-rate to compensate for the increased metabolic consumption of oxygen because of your muscles. You stay at the given pace/incline for a few minutes because your HR will jump at first, then slope down to a level that your heart and body is comfortable at. If you want to be absolutely safe and accurate in your measurements you could allow for about 5 minutes per fluctuation, but that would take a long time.
Numbers - There technically isn't any max, but if anybody has a number of above 60 either you did something wrong or your heart can handle a HUGE strain: it would imply that your HR(max) is at least 4 times your HR(rest), which is unlikely unless you're a trained athlete. My number, for instance, is 54, but I train every day and my resting HR is very low. Some athletes can reach 70-80 and above, but they would be world-class (such as olympians).
According to the Wikipedia page, the average VO2 is -
Men (untrained): 45
Women (untrained): 38
Note: If you don't have access to a treadmill, and/or a hear-rate measuring device, I would recommend using a local high school track and measuring your heart-rate with your fingers and a watch.
[1] http://en.wikipedia.org/wiki/VO2...