There seems to be a number of articles on the internet and a general consensus on this forum that think grip tightening for forehands is about providing extra propulsion by holding the grip loosely in the fingers then tightening.
In reality the effect of grip tightening can be likened to a boxer throwing a snap punch. Being relaxed then tightening on impact.
The grip should not be held in just the fingers for forehand shots. It should should not move a lot in the hand when tightening. The palm should touch the handle.
Heres a great slow motion video of the pros which clearly shows grip in the palms.
https://www.youtube.com/watch?v=NUp5duS9pp8
Here's a video from Lee Jae Bok. While I don't like his videos on smashing I think most of his videos are good. He shows the grip in his fingers for quick grip changes but note he tightens for forehand which is correct.
https://www.youtube.com/watch?v=5GJcdJm7UrE
In reality the effect of grip tightening can be likened to a boxer throwing a snap punch. Being relaxed then tightening on impact.
The grip should not be held in just the fingers for forehand shots. It should should not move a lot in the hand when tightening. The palm should touch the handle.
Heres a great slow motion video of the pros which clearly shows grip in the palms.
https://www.youtube.com/watch?v=NUp5duS9pp8
Here's a video from Lee Jae Bok. While I don't like his videos on smashing I think most of his videos are good. He shows the grip in his fingers for quick grip changes but note he tightens for forehand which is correct.
https://www.youtube.com/watch?v=5GJcdJm7UrE