Maintaining the Pump
Q: I try to do the approach that you suggested with the 3-days-a-week pyramid routine. The problem is that on my off days I feel like I'm
losing muscle. Or I have a strong urge to just go and lift, because I
don't feel pumped up. Is it normal to feel this way?
My Answer: Yes that is normal for some people, particularly ectomorphs. But there is a big difference between "feeling" like you're losing muscle and actually losing muscle. The pump that you get from working out is transient. It is temporary, and it is not a true indicator of your muscle size. Nevertheless, some people get addicted to the pump and want to have it all the time, so they go to the gym all the time.
If you feel like going to the gym every day, then go right ahead. Split the workout in half according to upper body and lower body. Alternate between upper and lower workouts throughout the week.
And because you've split the workouts in half, don't be tempted to add more exercises, because you will overtrain and lose the pump. The pump is indicative of your anabolic state. If you pump up easily, then this indicates your body is in an anabolic state. If you do too many exercises or your workout goes on for too long (over 45 minutes), then you will be unable to maintain that pump, because you've overstressed your muscles and the capillaries within these muscles have now collapsed.
So don't be greedy. Workout just enough to get the pump.