Another huge influence on your baby's development is his physical makeup. Some infants have what is called a low muscle tone, which may make it harder for them to accomplish gross motor skills. Muscle tone is the level of tension in the muscles when the body is at rest. Children with low muscle tone might be a little late in learning to roll over, sit up, crawl, and walk just because it's harder for them to initiate movement or maintain muscle tone during movement.
How can a parent tell whether a child's muscle tone is low? It's not easy. His arms and legs might be especially easy to move when relaxed, or he may seem to slip through your arms when you pick him up. A child with low tone is a bit floppy and perhaps not as quick to move about as a child with greater muscle tone.
The good news is that most kids outgrow low muscle tone after a couple years and end up on a par with everyone else. Some kids with low muscle tone benefit from physical or occupational therapy for a short period of time. Parents may be taught different exercises to do with their child at home to encourage muscle development. If the exercises are done on a regular schedule, most parents will see positive results fairly quickly.