Why oh why oh all the plyo? I happen to be cruising through the gym and I see trainer after trainer have their young charges doing these deep jump squats up to platform boxes four feet and higher. If they are volleyball or basketball players who need height I get it. If they are racquetball athletes I do not get it.
I once heard a trainer at a leading University state that the football players do not even begin plyometrics until they can squat at least twice their body weight. Without the muscle to protect the joints and tendons plyometrics are dangerous. That danger is compounded with young female and male athletes.
There are better ways to train and I am going to steal a phrase from Scott Phelps, my speed mentor and former speed training coach for the old Team USA back in the 90s; plyo-quickness. Working on your feet to hit the ground and take off in mult-directional drills works better than depth jumps as it is sports specific and safer. Make sure your trainer is knowledgeable and fully certified.
Then remember, even the best trainers need to know the demands of our sport. Often they are out of touch with what a tough racquetball match is. Rotational work, shoulders, lower back, and legs all need sport-specific conditioning. Find a good trainer who will push you and back you off when you need rest. Those folks are rare!!