Dare not practice standing piles. If you can't practice well, the problem will be big. If you have a problem with your knee, you can practice health piles first. It is recommended to practice sitting posture first. Wait until your body is adapted and strong, then change your standing posture. The initial stance should be appropriate. You should feel a little tired, and you can recover in time after a rest. The appropriate time is half an hour, and then slowly extend the time, but it does not mean that the longer the practice, the better. Suggest looking for a teacher.