Hey Sweetiele,
I know exactly what you mean. It is about finding the balance between being relaxed enough to get enough acceleration and speed through the ball whilst at the same time having enough tension to play strong and strike the ball firmly. Different shots require different amounts of tension, however overall we would emphasize that being to tense can make the recovery harder and the shots more effort and hard work.
I myself play with some tension in my forehand I find it allows me to generate more spin. I think Timo Boll is similar to this whereas Ma Long is a lot more relaxed. So it goes back to finding out what works for you and getting that balance 🙂
