[This is a series of posts I wrote for novice lifters I coach, but the information here applies to everyone. If you want to start at the beginning, go to Part 1: Recovering From Workouts -Dave]
First off, go read the Energy Systems And You article. It gives you most of the information you’ll need. Go on, go. I’ll wait here.
OK, you’re back. Now that you’ve read that article, you understand that your muscles can only store a finite amount of energy in the form of Adenosine Triphosphate/Creatine Phosphate, and that physical activity depletes that energy. You also understand that replenishing these ATP/CP stores does not happen instantaneously. It takes time.
In the case of an activity which recruites a lot of muscle fibers for an intense effort (lifting, for example, as opposed to non-sprinting running), this time is about 3 minutes. It can be more if the effort is particularly intense, or if you’ve strung together a number of intense-effort/recovery cycles one after the other (e.g., when you are doing 3 sets of squats). Thus you may find that, over the course of 3 or 4 tough sets of a lift, you need 3 minutes to fully recover at first, and then 4 minutes, and then maybe 5 or more minutes.
The other thing to keep in mind is the SAID principle. We are all here to get stronger. This means we want to do exercises (fully, through the full range of motion for that exercise) with weights that cause us to deplete a lot of our energy stores during a given set. Our bodies adapt to this by getting more efficient both at lifting and at replenishing our energy after a set. Moreover, you will have trouble executing exercises with good form if you don’t rest enough in between sets. Don’t sabotage yourself – take the time to recover!
The final thing to bear in mind is that you are all novices. Lifting is technical. Way more technical than most people think, and much more technical than things like walking or running (although of course good mechanics are important there as well). So you are not just loading up weight and doing reps. You are learning how to do the movements properly. You are developing the capacity to actually do the movements at all in some cases (e.g., most folks cannot squat below parallel properly without a weight at all).
So our SAID adaptations are not just about getting stronger right now. They are also about patterning the movements properly, and practicing them, over and over, so that when the weights do get heavy, you can handle them and do the exercises without hurting yourselves.
This is a long journey, not a short one. You’ll get better at the movements. You’ll get stronger. And the weight on the bar will go up.