The heart of training is the workout. This is when you create the potential for fitness. Notice the “potential” in the previous sentence. Fitness is not created in workouts. It occurs in the recovery period following a long or intense training session when the body changes by adapting to the stress you previously placed on it. The major change that happens during a workout is that fatigue is created.
Fatigue is a good thing. If there is no fatigue then the body doesn’t need to adapt. Fatigue is your sign that you accomplished something. Unfortunately, some athletes become addicted to fatigue and want to always be in a fatigued state. They seem to enjoy it. They are prime candidates for the overtraining syndrome. Fatigue must be shed when the accumulation becomes too great. That’s why there are easy days and rest weeks.
Workouts must have a purpose and you should always be aware of what that purpose is as you begin a session. You must then stay focused on that purpose. The purpose is usually to improve or maintain an ability (aerobic endurance, force, speed skills, muscular endurance, aanaerobic endurance or power). These are the hard workouts that leave you with fatigue. Of course, the other common purpose is to recover. These are the easy workouts. Athletes often become confused and forget what the purpose of the workout is, especially when around other athletes. This may happen while out for a bike workout and a group of riders come along. You jump in with them and all of a sudden you’re “racing.” Know the purpose of your workout and keep your focus.
There are only two things you can do to make a workout hard: You can make it longer or you can make it more intense. Of course, you can also make it longer and more intense. In the Base period of "classical" perozation the workouts emphasize duration – the make-it-longer method. Intensity also increases a bit during the Base period but not as much as duration. In the Build period intensity increases while duration stays the same as in Base or is reduced slightly.
“Intensity” in this case does not mean trying to go faster and faster with every subsequent workout. Workout intensity is directly tied to your race goals. In the race what do you want your pace, heart rate, power or perceived exertion to be? The answer to that question determines the intensity of your hard workouts in the Build period. All you will do then is focus on getting more and more time at that intensity to build race-specific fitness.
I have to say this often because it seems most athletes do not fully understand how important it is: For the advanced athlete how long your workouts are and how many miles, kilometers or hours you train in a week is not the ultimate determiner of how race-fit you are – intensity is. Do not become focused on duration or volume. Trying to continually increase these two in the Build period will not adequately prepare you for a fast race. To race fast you must train fast, not slow and long. Traning must become increasingly like the race. Once your workout duration and weekly volume are established in the Base period you have accomplished all you can in this regard. Turn your attention to the intensity of training at this point and keep it there.