Originally Posted by goran_ace
It really is different for each kid. Based on what people are guessing already you'd probably be surprised how little time some of these kids actually spend on the court. Not all elite juniors are academy kids or home schooled. I played at the same club as a kid who was top 5 in the country in 16s and 18s and he only played 1-1.5 hours a day 5 times a week. Coached by his dad (who was a teaching pro), went to a normal high school. Knew some other kids top 10 in their age groups and same thing. With the intensity of the practice sessions we did in our junior program when I was playing there is no way anyone could be playing 4-5 hours a day.
True, no doubt kids can be top 10 USTA and train less. But the true top juniors....top ITF, big difference in levels. They train split sessions, 4-6 total hours per day at high intensity.
I saw the top Russian kids first hand just a month ago and the intensity and duration is way more than I can remember even 5 years ago. I imagine some will fall due to overuse injuries.