1, damage to the knee, long-term use of one leg will lead to overwork, which is not conducive to the lower limbs and knees, and will eventually affect the height.
2, easy to get hurt, the child's sense of danger is weak, it is easy to fall, and fractures and concussions will occur.
3, it is not easy to find a good center of gravity, and it is easy to sprain your foot.