VO2max TrainingYou increase your VO2max by running fast followed by jogging for recovery. This is a fast pace but not "all out". Runners typically train for VO2max by running faster than their 5K pace for 3 to 5 minutes (the amount faster depends on the condition and age of the runner), with 4 or 5 minutes of jogging afterward for recovery. An example of a VO2max pace might be running intervals at 10-30 seconds per mile faster than the 5K pace. VO2max training is very stressful on your body, and beginning runners should not do it. VO2max training will cause heart rates to be 85% to 95% of maximum.
Estimating VO2maxInstead of putting great stress on your body to measure your maximum oxygen intake, you can estimate your VO2max. One equation that gives a reasonable estimation of maximum oxygen intake is the following
VO2max = 15(HRmax/HRrest)
That is, divide your maximum heart rate by your resting heart rate and multiply that quotient by 15. As one trains as a runner, his or her heart rate decreases because their body becomes more efficient in using the oxygen delivered to it, thus reducing the rate at which the heart pumps blood. The fast pace described above for measuring VO2max is a good way, probably the quickest way, to reduce your resting heart rate.
Look at the ratio of the two heart rates. You can increase your VO2max by increasing your maximum heart rate or by decreasing your resting heart rate. There isn't much you can do about increasing your maximum heart rate, because that is a product of the biological properties of your body. But, there is a lot you can do to reduce your resting heart rate. The fast running that is described above will, over time, decrease your resting heart rate. For example, a typical heart rate for non-athletes is 70, although that value varies with the individual. During my mid 40s when I ran marathons, my wakeup (resting) heart rate was 44, and it dropped to 40 as I trained for marathons. During marathon training, my resting heart rate was significantly below the typical heart rate for non-athletes, indicating that my body received more oxygen per heart beat than bodies of typical non-athletes. Although I'm no longer training for marathons and am older, my wakeup heart rate is 53 and is still below the typical values of non-athletes. And, my VO2max (estimated 45) is significantly higher than that of non-athletes my age (estimated 28 - 35). During my marathon training, my estimated VO2max was 67.