Originally Posted by Centerforward71
You are pretty correct but let me make a point.
Tennis as is golf and all sports with body motion is about kinematic sequences. I don't want to get overly scientific here but the pronation and supination are at the end of a sequence of other events leading up to it. At this point a correct sequence can allow a good player to over or under supinate/probate to achieve a desired effect. So to your answer while not wrong I will till you it's not 100%. I've played professional level sports and can tell you that you do manipulate as needed the pron/sup sequence at times and when needed. You cannot have the same supination for a flat 1HBH than for a loopy top spin one. That said there is a different kinematic sequence as well. Now do I consciously think of it? NO but your CNS tells your body to do so. Again if the kinematic sequence is wrong approaching the point of pro/sup then thinking of that as more or less will probably only enhance the previous error.
In summary worry about good grip, good footwork, good rotation to impact, good impact zone/timing and when you get there trust me your good enough to start over/under or natural pro/sup to get a desired effect on the ball.
On my 1HBH if I want to go sharp,cross court I start sequence earlier, hit a little earlier and to create a sharper angle I increase supination and upward stroke on the outside part of the ball. Now this happens by practice and subconscious effect when playing. There is no way I could think that in the middle of a point.
Hope this helps
That's a really good explanation. Thanks.