http://www.feeltennis.net/classic-vs-modern-forehand/
Have you ever wondered what it means that the forehand is “modern” and how it differs from the “classic” tennis forehand technique?
And what should you do if you’re currently playing with a more classic forehand technique but you would like to transition to a more modern forehand?
Answers to these questions can be found in the video above where I demonstrate both types of forehands and show you what the real difference is.
As you will see the classic forehand hit more like a one rigid unit where the arm is not bending nor does the body coil.
The modern forehand on the other hand is segmented which means it has many more moving parts that create a very powerful kinetic chain.
While this creates more power and it is also more difficult to control therefore it’s not really the best idea to try and copy the pros if you don’t practice as much as you’ll make too many mistakes.
source