Like here, https://www.youtube.com/watch?v=Ya4JCQi3io4 11 minutes 25 seconds onwards. You get a good view of Wang Yihan's strokes, obviously she is not putting full effort into it, but I'm interested if her action is suitable to watch and learn from? She looks very relaxed and elegant.
Yes they put effort into warming up, after all they need to get used to the court, drift, environment, feel, and bird. They are activating their muscles in succession to proper technique, biomechanics, and training. Obviously we don't see everything as they are not adding 100% of their muscle into it, since they need to save energy for the game. I would probably advise from watching them warm up to learn, because there are many things that you probably don't notice them do while warming up, that are more obvious when they are actually trying. For example, muscle flexion is much more obvious when they play for real.
