While I've previously explained that stretching seldom helps improve your flexibility in the long term, there are some benefits that come from stretching. This exciting study from 2015 done by Miranda et. al. tested stretching as a means for increasing training volume (the number of repetitions performed in a set or session) in the wide-grip seated row exercise. There were two groups of participants, both of whom performed three sets to failure with two minutes of rest in between sets. The only difference between the groups was that the experimental group performed 40 seconds of a passive pectoralis major stretch at the end of their allotted rest periods. The idea here was to stretch the antagonist (opposing) muscles.
What the experimenters found was fascinating: there was a statistically significant difference in the antagonist stretching group. Those participants performed more repetitions in all three sets. Additionally, the experimental group demonstrated greater contractions in the latissimus dorsi and the biceps brachii muscles.
While this particular study only tested one exercise, it is likely that we can utilize this concept with other movements to reap similar benefits. For instance, in doing a bench press, you could stretch the latissimus dorsi. Before your set of leg curls, stretch out your quadriceps. You get the idea. This hack can help you get more training volume, which will ultimately result in greater hypertrophy (muscle growth)!
The mechanisms behind these findings are still unclear. My guess would be that stretching the antagonist muscles would allow for greater range of motion throughout the exercise, and thus, a stronger contraction in the agonist muscles. For example, the pecs have to stretch during the top of the rowing exercise. A bigger stretch in the pecs could possibly allow for the lats to generate a stronger contraction.
Static stretching before a set may be disadvantageous for power production, and thus, I do not prescribe it before movements like the clean and jerk. However, in a bodybuilding routine, there may be some added bonuses to stretching during rest periods to accumulate more total training volume.
This concept has not yet been applied to strength-based movements, but it could be an interesting point for experimentation on your own before the big lifts. Give this trick a try and see how you like it!