“All growth depends on activity. There is no development physically or intellectually without effort, and effort means work.” –Calvin Coolidge
Babies are bundled up in the womb with their knees to their chest, hips wide and rotated outward, and feet turned in. The muscles and bones keep this position when they are born, this is known as physiological flexion. When a baby is on their back, you will continue to see the hips, the knees, and the feet in flexion. When a baby plays in tummy time, their bottom will stick up in the air, this is also due to the physiological flexion. With more room to move and the full effects of gravity, the posturing throughout their body adapts. As babies begin to stretch out over the next two months, you will notice them kicking their legs straighter. In tummy time, you will also see less hip flexion, with the hips coming closer to the surface.
When a child starts sitting by themselves, the back is round with the weight forward in front of the hips, until enough core strength and balance develop to sit up straight. The natural curves throughout the spine have not developed yet. A baby may start sitting with their legs wide and knees straight, creating a broader base of support. Eventually, when sitting with improved core stability and balance, the baby finds it easier to move the legs in various positions, allowing for dynamic play.
As the baby pulls to stand, cruises along a surface and begins to walk, their legs are wide with their feet pointed in or out and their knees locked. As they improve these skills, their feet come closer together under their hips, and their legs will not appear as stiff.
Toddlers try out variations of walking before finding the most efficient pattern. You might see them up on their toes, with their feet turned in or out, or walking with stiff legs. These patterns should be intermittent and will eventually pass.
Wolff’s Law states that healthy bone adapts to the load placed on it. Over the first few years of standing, walking, and running, the bones in the legs mature and adjust to the forces exerted on them. The child’s hips will come into neutral, and their feet will start to straighten out and develop arches.
If you see a consistent pattern that you are concerned about, reach out to your pediatrician.