Wave your arms in the air! The invisible mechanics behind it

When we think about waving or moving arms through the air, although it may seem straightforward, your toddler needs to make a complicated, synchronised movement to do this. It’s not until we delve into the magnificence of how our bodies make it happen that we can appreciate every tiny step of progress your toddler’s striving to achieve. 

Let’s start with the skeleton, which consists of bones, joints and cartilage, and is the foundation of the body. 

Joints are the place where two or more bones meet, and most of our joints move. They are connected by ligaments, and these stabilise our joints during movement, absorb shock and help maintain correct posture and movement. 

The joints in our shoulders and elbows are known as synovial joints; this means they move freely. Muscles and tendons allow movement of our joints and bones. 

To wave their arms in the air, your toddler lifts them by raising the bones in their arms and shoulders straight forwards or to the side. Once their arms are in the air, their muscles and joints work together to keep them lifted and to move from side to side.  

Each time your toddler waves their arm in the air, it crosses the midline 

This is an invisible line that runs straight through the middle of the body, it figuratively splits the body in two from the top of the head down to the feet, dividing it into left and right.  

Crossing the midline is important for many gross and fine motor tasks  

Being able to cross the midline helps your toddler in lots of daily activities like drawing, cleaning their teeth, doing action songs and other fun stuff. 

Yet when it’s combined with an overhead action like waving, it helps your toddler build the core stability and strength they need to stay upright and balanced. This will be really handy for when they play bat and ball games and many other sports. 

The ability to cross midline helps your toddler to develop a dominant hand  

This might be surprising to hear! Research suggests that when toddlers cross the midline in play and in tasks, they will start to use their dominant hand.[1] For example, when they take a piece of a jigsaw that is placed to one side of it, you might start to see a trend in which hand your toddler uses to reach for it.  

So, when your toddler waves something in the air, watch which hand they use to hold it – you may start to tell whether they’ll be left-handed, right-handed, or ambidextrous. 

Reference: 

[1] M. Carlier., A.L. Doyen., C. Lamard. (2006) Midline crossing: Developmental trend from 3 to 10 years of age in a preferential card-reaching task. Brain and Cognition. Volume 61, Issue 3. Pages 255-261.