Patient's question:
According to what I read, a 4-month-old baby's movements should show symmetry. What does this mean? Does it mean that the baby's two arms must move exactly the same way at every moment, and the two legs must also move exactly the same way? But my baby isn't like that. She might bend both arms, or extend both arms, and the same goes for her legs. Is this normal?Doctor's answer:
Hello. The child is normal. Don't be nervous. The principle of motion economy refers to the economic law that allows a person to achieve the maximum work effect with the least amount of labor when operating tasks. It is important to study and apply this principle well. In factories, we can observe many actions that do not comply with this principle in many places. Of course, work efficiency will be low, and personnel will be prone to fatigue. If both hands move in one direction, it will cause a shift in the body's center of gravity. Maintaining this balance will lead to mental and muscular fatigue. The most labor-saving way of operation is when both hands move symmetrically in opposite directions.