Here’s a fun video of pull-ups. The first 2 reps are power ups, second two are regular slow and controlled pull-ups.
Interesting thing happened when shooting this. I was planning on doing the slow pull-ups first then go into the power ups. I couldn’t do the power ups on the first attempt after doing the slow pull-ups.
My conclusion, same exact reason we never stretch before sprinting or lifting. Muscles have memory.
Think about it. In order for a muscle to work it takes an electrical impulse from the nerves to start the action. Now think of this nerve-muscle connection as software program. When you mentally prepare to perform an activity that requires speed and power, that muscle software is programmed for high performance effort. Dynamic warm-ups that mimic the motion and speed to be performed are ideal for setting this muscle software up.
So conversely, static or holding a stretch is setting the muscle software up for a flaccid or relaxed muscle that is not geared for activity.
So for a “warm-up,” we need to re-set the muscle software towards high performance activity which is what a good dynamic warm-up does.
A static stretch where you hold a stretch is ideal for the end of the workout when you want to settle the muscles down and increase flexibility.
One aside, I don’t believe in actually warming up. We’re already at 96-99 degrees in body temperature (people do vary). I think that’s warm enough. The purpose of the warm-up is to re-direct blood flow to support the muscles, heart and lungs. Where after eating a meal the blood flow is more focused around the gut. The other purpose of the warm-up is again to re-set the muscle software to have the nerves stimulate the muscles in a high performance mode.
Back to the pull-ups paradox. I had difficulties doing power ups after slow pull-ups because I was in “slow moving” mode. Switching immediately to fast mode created a software error in the muscles and I failed.