Here's another graph of the 3 energy systems, how much energy they give when they fire and how long that fire, or energy, lasts. The names are changing a little here because there are lots of ways to refer to some of these systems, but know the 1st one (here called CP) lasts for 8ish seconds, the second one (here called Glycolysis) lasts for about 40 seconds before it starts to have issues, and the 3rd one, still called the Aerobic system, has to already have been getting going this whole time so it's ready to help out when the first two "gas tanks" are spent.