Originally Posted by sportsfan1
In pics 10, 11, 12 Sampras's non-hitting arm is coming down, but it doesn't come straight down (vertically, like a fist pump), but rather seems to come down horizontally or at some angle. Anyone else notice that and have any thoughts/explanation on the reason behind this? Is that just an individual habit/quirk?
Well, not an expert here, but I have played around a lot with the non-hitting arm for different strokes and developed some strong opinions.
It is, of course, very important to train the non-hitting arm to do the right thing at the start of a stroke such as a forehand or serve (as discussed extensively in various threads). Just as important, is the necessity to leave it alone during the latter part the stroke to do what is necessary for maintaining the right balance - IMO, the body/brain will know what to do. If we try to move it like Sampras or someone else, it may not be the right thing us. The way the non-hitting arm moves will be a side effect of how one executes the stroke, and also dependent on the individual's unique physical characteristics.