Kinetic energy (KE) is the release of the elastic energy stored in the tendons and tissues of the body and it is gathered in the eccentric phase of a movement.
So what does this equation mean to you and why is it important in the gym? Ultimately, it is easier to increase kinetic energy by increasing velocity rather than mass because velocity is squared.
I will use the back squat as an example here. It’s smart to use the stretch reflex at the bottom of your squat if you want to move more weight. Using the stretch reflex means using your stored KE. Going with gravity (the down phase in the squat) is known as the eccentric movement and the upward is the concentric. You are 40-50% stronger in the eccentric phase than the concentric. This might cause some to lower in the squat slowly, which is counterproductive. A faster descent stores more KE and the stretch reflex is magnified, making it easier and faster coming out of the hole.
In a nutshell: fast down, fast up.
We’ve recently incorporated band work in our sessions. Banded squats force you to speed up the eccentric phase, increasing velocity, which creates more KE and speeds up the concentric phase. This is a great form of speed training.
One last thing I want to mention. You might have noticed that power lifters squat with a much wider stance than Oly lifters. A wide stance allows the lifter to engage the hamstrings earlier in the lift. As soon as they pass parallel, they fire the hamstrings to drive out as fast as possible. Oly lifters, on the other hand, use a narrower squat stance and typically go much, much lower than parallel. The narrow stance delays the stretch reflex until the lifter is almost ass to grass because hamstring tension requires this sort of depth. Shoving the knees out can engage them a little sooner. Train for your sport. Everyone’s squat stance is a little bit different.
Now apply this technique to other movements. When doing a handstand push up, descend a little faster (without cracking your neck) and fire up fast. During multiple reps of presses, think “down fast, up fast.” The same applies to multiple reps of deadlifts. There is no KE stored with the first pull off of the ground because you can only move concentrically from there. You can store some major KE in your next rep, however. Don’t drop and reset. Do all that you can to touch-and-go so you can apply your stored KE. How about toes-to-bar? It’s easier to string reps together when you are fast out of the bottom and straight into another rep.
Focus on improving your speed in lifts and movements and you will see improvements in your strength and your performance in WODs.