How should he prepare to race? Periodizaion or training is a good start since it is very difficult to train to maximize every system at the same time. So basically we have the base period to develop your aerobic capacity to its maximum. Then you have your precompetition phase where you maximize your event specific power requirements, be it aerobic power or anaerobic power. Anaerobic capacity fits into the Base phase of training. As I stated earlier we don't want to over stress our aerobic system and over train, so we need to have our anaerobic capacity at least moderately high during this phase of training, this way we can perform more running that actually is improving our aerobic capacity. The best way to increase your anaerobic capacity is by performing short close to all out short sprints. You want to increase your body’s ability to use sugar as its main fuel source. If you start to sprint the energy created to run is mostly provided by creatien phosphate. After about six seconds your glycolic (sugar burning)system begins to provide most of the energy needed to keep running. When performing these workouts it is important not to run so far as to begin to actually strain and tie up. If you run past this point you will be training your anaerobic power, not your anaerobic capacity. How far you can sprint before this happens is really an individual matter. You can usually tell though. You shouldn't do too many repeats of fast sprints either, or you will break down in stead of build up. About six repeats is about right. You can probably do two of these sessions per week, preferably near the beginning of your LSD runs and after a good warm up. You don't want to be glycogen depleted for these workouts or you will not have enough fuel to maximize sugar utilization. Performing these workouts at the end of a longish run will increase the chance that you are low in the required fuel. After about six weeks of this training you should see an increase in the maximum amount of lactate you can produce in an all out 600m run.
The difficult part is trying to figure out what level of anaerobic capacity is right. It is different for each phase of training and each type of runner. We don't have to worry so much about aerobic capacity because we want it as high as possible, but with anaerobic capacity it really depends on which event you are running. Sprinters really need high anaerobic capacity, while marathoners need a very low one.
In the Base phase of a marathoners training, it would be important to have a relatively high anaerobic capacity as measured with a lactate meter. A good level would be about 10 mmol/l for a marathoner in this phase of training. Not so high that they can not perform a large amount of volume, but high enough that they will have a difficult time tryin to lower in when the time comes to run the race. A marathoner really needs to have a maximum lactate reading of about 5 mmol/l on the 600m sprint test when they are ready to race. If it is not low enough they will produce to much lactate at every speed and will either have to run really slow in order to be able to finish the distance at a constant speed, or they will try to run at a desired speed and run out of fuel and hit the wall or bonk. Anaerobic energy is created by utilizing sugar as its fuel source. Since stored glycogen is very important to a marathoner they would not want to run out of it sooner than the end of the race.
At the other end of the spectrum is the 200m runner they need a crap load of energy to be provided very quickly. Aerobic energy is not produced fast enough, but lactate can be created very quickly by a runner with a high anaerobic capacity. Individual differences in levels of anaerobic capacity is one of the reasons some people are slow and others are very fast. If you can't produce energy quickly you aren't getting anywhere quickly. The difference between a marathon runner is that they are an efficient vehicle like one of those new hybrid vehicles, they aren’t very fast but they utilize fuel efficiently and can go very far at a relatively quick tempo without slowing down. A 200m runner on the other hand isn't very fuel efficient, he is like a mustang, he can run the quarter mile fast but he will be lucky if he can even jog a marathon. He just uses up fuel too dam fast. It is perfect for his event though.