Of course.
Did this exercise thicken your legs at first?
Illusion, just because you haven't been exposed to such intensive training, it was edema at first, and it will be fine in a week. You'd better use a soft ruler instead of visual inspection or other methods, and you'll know in two weeks.
Stick to it for a while, will you lose weight like running?
Yes, very different from jogging, what HIIT really achieves is to reduce fat rather than weight. Simple aerobic jogging is too inefficient in reducing fat and shaping.
After a year or two of fitness, my muscles have changed a little. Will it be more developed to practice like this again?
If you know your training plan, you will know whether you are muscular or not. To tell you the truth, you are a little too anti-muscle. Hip-butting, stovepipe, chest-lifting, and farewell to flesh and meat all rely on muscles to make the body lines tight and thus have the so-called curve. Generally speaking, it is impossible for women to grow a lot of muscles without using supplements, because the testosterone secreted by women is really limited.
Is it too long to exercise for about three hours six days a week?
If three hours a day is too long for ordinary people, I don't know what your exercise goal is, and it's hard to say. For ordinary people, if you exercise for three hours every day, you can basically infer that your exercise intensity is too low and your exercise time is too long. Generally speaking, it is more appropriate to exercise 3-5 times a week. Whether it is advanced or amateur, 6 times is no problem. If it is three hours a day, if it is not a professional, it is really too long, but it is not good for your health.
Will it cause muscle dissolution?
If you have long-term exercise habits, it won't lead to the terrible symptoms of rhabdomyolysis, but if you sit still all the time and suddenly get up to do 500 push-ups or 700 squats, it may lead to rhabdomyolysis and then die.
Finally, in view of your problem and the scheme you have adopted, I suggest that you can learn some fitness knowledge in Zhihu and other places. In terms of books, I recommend Binka's Hard Fitness.