I'm a high school tennis player for a competitive high school and I've been looking for every advantage I can add to my game of the court. Recently, I started following the starting strength program (which consists of compound lifting exercises like squats, deadlifts, OHP, etc). Then I read an interview with Alexander Zverev (http://www.spiegel.de/international/alexander-zverev-wimbledon-interview-a-1156983.html) where Zverev said that doing too much for your upper body is bad for your stroke, I was wondering if this was true and if weight lifting for upper body could really affect your strokes and how it could.