Children are in a long-term physical development stage, young adults pursue self-defense and martial arts, and the elderly practice Tai Ji Chuan to pursue health preservation. This requires everyone to be familiar with the moves first, discuss with the coach to see if it is suitable for their own practice, and then start practicing.
Warm up every time you practice boxing. If the boxing frame is too low and the knee is stressed too much or even more than the hip joint, the knee will definitely hurt. The tip of the knee should not exceed the toe, and the tip of the knee should be in the same direction as the toe. Swing buckle feet should turn in the same direction as knees and toes, and move in the same direction synchronously. Especially novices, don't be too eager to imitate the coach's posture, from elevated to low, from outline to concrete, stand well first, stand well, then practice the hand posture and so on.
If your knee hurts, you should see a doctor as soon as possible. We should learn to study and practice boxing, not to be superstitious or mysterious, so that we can all make healthy progress.