The purpose of training, for the competitive runner, is to build race fitness. To achieve this objective, whether the race in question is a 5K or a marathon, your training must evolve in two dimensions as the weeks go by.
Your total workload must increase, and your race-specific workload must increase. There is no way to build race fitness without working steadily harder in these two ways. It takes a bigger training input to get a better race performance output. Any other way of improving race performance would amount to magic—and magic is not real.
What does it mean for your training workload to increase? It means you’re running more total miles per week, or your average pace for your total weekly running mileage is getting faster, or both. What does it mean for your race-specific workload to increase? It means you’re running more high-intensity miles per week and/or your average pace at the higher intensities is getting faster.
I’ve implied that both your training workload and your race-specific training workload should increase simultaneously at all times, but this is not actually the case. They can, but in many cases it’s preferable to focus on building the general training workload in the first phase of the training process and then focus on increasing the race-specific training workload in the second phase, allowing the total training workload to plateau or decrease slightly.
There is also a need for periodic “recovery weeks”, in which both the total and race-specific training workloads come down to give your body a chance to absorb recent training and prepare for harder weeks to come. Typically, every third or fourth week should be a recovery week. The overall trend of your training, however, should always be one of increasing work.
The best way to balance increases in general and race-specific training workloads depends primarily on the distance of the race you’re preparing for. If it’s a shorter race (10K or below), you should concentrate on building your general training workload during the first phase of the training cycle while keeping your race-specific workload fairly low.
In practical terms, this means your total weekly running mileage should increase while your average pace for your total running mileage holds steady or becomes very gradually faster. Meanwhile, the number of miles you run at heart rates equal to and above the heart rate associated with your lactate threshold pace (or the fastest pace you could sustain for one hour in a race) should hold steady at a low level.
In the second phase of training for a 10K or shorter race, your total weekly running mileage should plateau and then slightly decrease as your weekly mileage run at heart rates equal to and above your lactate threshold heart rate increases. Your average pace at these higher intensities should also become faster, and so should your average pace for your total weekly running mileage.
If you’re training for a marathon, your total training workload should increase straight through until you begin to “taper” two to three weeks before your marathon. During the first phase of training, the amount of running you do at your goal marathon pace and faster should stay fairly low, although your average pace for all of your running should get very gradually faster. In the second phase, your weekly running mileage at marathon pace and faster should increase, and your average pace at these higher intensities should get faster. Meanwhile, your total weekly running mileage should increase at a lower rate. For very high-mileage runners (100-plus per week), it may plateau.
If you’re training for a half marathon, the two-phase pattern of your training should fall somewhere between these suggested short-race and marathon patterns. For high-volume runners it should look a little more like the short-race pattern; for lower-volume runners it should look at littler more like the marathon pattern.
These simple guidelines provide an easy means to monitor whether your training is on track throughout the process of preparing for any race. Simply track your weekly mileage, your average weekly running pace, your weekly mileage at either your lactate threshold heart rate and above or your goal marathon pace and above, and your average pace at these higher intensities—and match these numbers against the guidelines I’ve given you. This will tell you whether your training is moving in the right direction—whether you have the right training inputs to produce the race performance output you seek.
It bears mentioning that any number of different specific training plans could do the job. There is more than one way to build race fitness. The one thing every plan has to do is move in the right direction. The details of how you achieve this direction are relatively unimportant. Now you know how to define the right direction and measure the direction of your training.