Base training in the off season is important for several reasons:
1) increase your aerobic capacity. The muscles contain mitochondria, also referred to as the "powerhouse of the cells". It is the ONLY place where aerobic respiration takes place. The more mitochondria you have, and the bigger your mitochondria, the more efficient you are with your aerobic capacity. Don't you want to be able to take more oxygen in so your body can make more ATP, making you faster and stronger in your rides?
2) You'll also build more capillaries, and base training will do that. Capillaries are the vessels where oxygen is transferred to the working muscles. Of course, if you've got more oxygen, you've got more ATP to work with, which means your muscles will work more efficiently. At the same time, CO2 diffuses from the muscles (that's waste products we don't want!) and out of the body. We want that too!
3) Because you've got a bigger base from training, it'll take longer for lactate to accumulate, and you'll have to work harder in order to produce lactate. More oxygen means less lactate produced. Also, with more oxygen, when you do move into training to increase VO2 max, you'll be able to work harder because you've got more oxygen, which means it'll push your VO2 max higher. We want that too!
4) With more efficiency at using oxygen, you're using fat as your primary energy source. Fat is only burned in the presence of oxygen, and when you're exercising, you want to burn more fats as your energy source. We want that too!
Besides all this, base gives you a good mental break from high intensity training. You can't go hard forever. Sometimes, training smarter, not harder, is the best route to go. Base building gives you that option.
koffee