Most road racers are familiar with events such as the 5k, 10k, half marathon, and marathon because these events are the ones contested most frequently. The good news for those who are racing the mile is that you primarily use the aerobic system as well.
The research on this topic suggests a range of 75-85% of the energy used to run the mile being supplied by the aerobic system, with the more current research tending to be on the higher side. A 5k will be 90-95% aerobic and a 10k will be 95-97% aerobic and a marathon 99% aerobic.
If you are looking to improve your mile time, all you need to do is spend a little bit more of your training focused on the anaerobic system. Most road racers already have the aerobic base built up; they just need to add in some anaerobic work. I like to do this in two ways: I call them short and long anaerobic work.
Short anaerobic work is done at current mile pace. Repetitions are from 200 meters to 500 meters in length, and recoveries are double the time you just spent running. An example for a 6 min miler would 12x200 @ 45 seconds with 90s rest. I try to keep the total volume of a workout between 1.5 and 3 miles depending on the level of the athlete. This works on your economy at race pace
Long anaerobic work I will do at reps as low as 400 and as high as 1600, primarily between 600 and 1200. Long anaerobic work is done between your current 3k or 10k race pace. I start with 5k pace and the recoveries are generally equal to the time you spent running. When moving to 3k pace, the times get faster by 2-4s per 400 and the recoveries go up to 1.5x the interval run, for 10k pace the times get slower by 2-4s per 400 and the recoveries go down to 50-75% of the interval run. Total volume of there workouts are between 2 and 5 miles depending on the level of the athlete. An example for a 25 min 5k runner would be 5x800 @4:00 with 4:00 recovery. This works on getting your body more used to processing the lactate buildup.
When racing the mile, just like other races, it is important to run even. If your body is ready to run a 5 min mile, it is best to go out at 2:30 for the first half and 1:15 for the first quarter. But what if you don't know how fast you are ready to run? The internet has good resources such as McMillan Running Calculator and Jack Daniels VDOT charts where you can plug in your most recent 5k time and it will let you know approximately what you are ready to run in the mile.