VO2 max, or maximal oxygen uptake, is considered to be one of the best indicators of aerobic fitness. It indicates the amount of oxygen you are able to pass on to your muscles. The higher your VO2 max, the faster or longer you can perform at top levels. VO2 max stands for the volume of oxygen you can use while exercising at your maximum level. The top level ever recorded by an elite athlete was in the low 90s, but many top athletes have VO2 max in the mid-70s. Most non-elite athletes have VO2 max in the range of the mid-40s to the mid-60s. Part of your VO2 max is genetic. Scientists have discovered that heredity accounts for about 50 percent of your ability to increase your endurance.
Since you can't pick your parents or your genes, you still have about 50 percent of VO2 max that you can train. The first step is consistent aerobic conditioning. This will increase your VO2 max over time, but the fastest way to reach your full VO2 max potential is to do intervals. When doing intervals, shoot for the fastest pace you can maintain at a pace known as velocity.
Velocity is the equivalent of your best 3000 meter pace sustained for about eight minutes. However, you don't need to maintain velocity for a full eight minutes on a regular basis. Just run at velocity for two to five minutes, at least once a week, and you'll maintain and gradually increase your VO2 max.
Another way to improve VO2 max is to work out in such a way that your heart rate stays between 65 and 85 percent of maximum at least three to five times a week for at least 20 minutes. Or run at maximum speed for five minutes, noting the distance you are able to cover in that time. Rest for five minutes, then run that same distance again, only 20 percent slower this time. Repeat this slower run, with 30 second rests in between each run, as many times as you can. Another option is to run flat out for three minutes, again noting the distance traveled, and repeat several times, running 10 percent slower, with 60 seconds rest in between.
Following each interval, your heart rate should recover to 120 beats per minute during each rest time. If this is not happening, extend the rest periods to allow your heart rate to drop to 120 bpm or lower each time. Make sure you allow the complete recovery time between each interval.
If you are running at altitude, your VO2 max will decrease as you go to higher altitudes. If you need to perform at peak levels at high altitudes, make sure you get to altitude several days early so you can acclimate and train. Start out slowly while your body acclimates, gradually working your way back to peak performance.
It's natural for your VO2 max to decrease as you age, so don't be alarmed if you have a harder time increasing or maintaining VO2 max over time.