Below is a 45 minute presentation that Dr. Mark Kovacs provided to hundreds of High School Tennis Coaches. It goes into some real depth around the theory behind the warm-up period, but also provides dozens of exercise examples and reasons behind the exercises.
If you are a High School coach or someone who teaches, coaches or trains the High School tennis player, we highly recommend you look at the Tennis Performance Trainer (TPT) certification program. It is designed to help you better understand and deliver tennis fitness and sport science information to your players to help them improve performance and reduce the likelyhood of injury.
Our Parent's Guide To Basic Injury Prevention is also a really great resource for anyone working with the High School Tennis Players.