This is where an athlete will benefit from an experienced coach, and what separates an excellent coach from a good coach. An excellent coach will urge you just that little bit extra past your limit (105%), and then call it a day, knowing that this steady increase will pay off in the long run. A good coach may be able to push you way past your limit (150%), and think he's done a good job but doesn't realize that perhaps the next day you can't play because of pain in your joints. I definitely understand where you're coming from though, especially when being cautious about injuries. At the end of the day, athletes can and should be pushed past their limits but it is the coaches responsibility to know each individual's threshold.
The athlete should know what their limit is too. If they can feel that a movement is weak or they fear hurting something, they need to say so too! Both coach and athlete are responsible.
