If you are new to running or you want to start training for a specific race, it is advisable to complete a foundation program first. This simple program should build up your fitness and running capability. Over the weeks, you should gradually increase your running distance, while also working on your stability and strength using core and resistance exercises. If you begin a specific plan without first following a foundation program, your body may not be adequately prepared. As a result, you are less likely to produce your optimum peformance and more likely to suffer an injury.
WHEN TO DO A FOUNDATION PROGRAM
If your goal is to run 3.1 miles (5 km), you don’t necessarily need to do the foundation training—the 3.1-mile program on is sufficient. If your goal is 6.2 miles (10 km), do the first four to six weeks of a foundation program to help develop your running strength and endurance. If you are training for a half marathon , follow a six- to eight-week foundation program before you start on the specific race training; for a marathon, undertake at least eight weeks before starting the specific plan. Stop running for a week between the two programs and rest or cross-train. This transition week gives your body a recovery break from running.
Three to four running sessions per week will adequately prepare you for a 5-km (3.1-mile) race. The runs should be increased gradually, so that you build up to your target distance, and varied to ensure that you remain stimulated and motivated. The inclusion of one cross-training session per week will increase your aerobic capacity and muscular fitness while also giving your running joints a rest. It is also important to give your body time to recover between training sessions, so you should have two or three rest days per week at the start. If you are training for a specific race, it is advisable to reduce your training for the last two weeks before, known as tapering.
ADDING A FOUNDATION PROGRAM
If you have done a 3.1-mile (5km) race before, or are already an athlete , you might want to focus on increasing your speed. Following the foundation program for four weeks and then undertaking the 3.1 mile (5 km) program opposite would help you increase your overall body strength and running endurance, and should lead to better performance and a faster race time. If you are an experienced 3.1 mile (5 km) runner, you could add one or two miles to some of the sessions suggested in the sample program to improve running fitness and performance over the distance. Use your training logs to make informed decisions about where to adapt your training load and always listen to your body. Don’t run more than 25 miles (40 km) per week during weeks five and six; it’s unnecessary for this event and there’s a risk of overtraining, and therefore injury.
To prepare for a 6.2-mile (10km) race, you will need to do four to five running sessions per week, with two rest sessions to allow your body time to recover. Adding at least one cross-training session every two weeks will give your body a break from running, as well as work on your aerobic and muscular fitness. A two-week taper period at the end of the program will ensure that your body is prepared for a race.
PICKING UP THE PACE
If you have never run a 10k race before, it is advisable to follow the first four to six weeks of the foundation program on to develop your running fitness. You should then be sufficiently prepared to progress to this specific 10k program and avoid the risk of overtraining. Experienced 10k runners who want to run faster can benefit from following a full foundation program before undertaking the 10k program. If you are an advanced 10k runner, add 2–4 miles (3–6 km) to some of the sessions, depending on where you feel you need to improve. Do not exceed 40 miles (64 km) per week during weeks five and six because anything more than this is unnecessary for this race distance.
taken From "The Complete Running and Marathon Book" -- OmRiyadat