https://www.scientificamerican.com/article/how-to-maximize-your-workout-with-push-pull-strength-training/

As much as I enjoy my exercise time, I don’t want to burn all of my daylight hours at the gym. I’ll bet you’re the same. So, when I am interested in building some muscle, I prefer to perform a push-pull strength training workout. This strategy gives me, and many of my clients, muscular and strength results in a lot less time.

In a nutshell, a push-pull workout is one where you choose a single muscle or muscle group and perform a set of exercises that use those muscles in a pushing direction. Then—either immediately or during your next workout session—you focus on that same muscle or muscle group, but you move in a pulling direction.