The simple answer is YES.
Lets just think about muscle physiology for a second. As a matter of fact grab yourself a rubber band. Hold one end with your right hand and pull the other end back about a quarter of an inch. When you let go, it didn’t go very far. Now, try it again, only this time pull it as far as you can, then let it go. Obviously, there was a big difference.
You see, the act of lifting something heavy is only done with a muscle being loaded (i.e. stretched closer to its length limit) So without a doubt “stretching” of some sort should take place during a session. When we talking about strength performance, I think everyone kind of already knows this. I mean, its usually apparent when we look over at the squat rack and we see people squatting with no weight or just bodyweight prior to loading up a bar. Sure, they may be just getting blood flow to tissue but movement prep is also the best way to stretch.
Remember the principles of specificity. Basically, we cant expect to get better at baseball by playing golf. If we want to get stronger at a movement, and we know that being able to take our joints through their full expression, then the most ideal way to stretch is in a manner that mimics the motion we are performing.
With that being said, lets head back to the squat rack for an example. Typically there will be some prep work that clients have already done but as your gearing up your sets to your work sets on the squat rack you can use your rest period to help you turn on and off appropriate muscles. One movement you can use is the 4 point squat.
from a squat stance, bend at the hips like you are trying to touch your toes and just hang. Next, drop your hips, grabbing your ankles and pushing out with your elbows. Raise one hand at a time to and overhead position keeping the neck packed in. Finally, stand by pressing through the heels of your feet. Repeat for repetitions.
hope this helps,