Can stand on one foot for a few seconds and then hop
By now your toddler will have been building on and extending the basic skills they learned when they were younger. They may have now extended their skills in standing by reaching and stretching. They will also have been exploring moving using one leg at a time in activities such as climbing and running.
Static balance
It is around this stage that your toddler will be gaining the physical skills required to stand one leg, this is called static balance. Standing on one leg requires a lot of stability from your toddler’s body as they need to hold their body in an upright position with control. When a toddler has achieved static balance, they will be able to stand on one leg and use either side of the body independently. [1] Being able to balance on one leg is important for many daily tasks and activities such as kicking a ball, putting on shoes and stepping in and out of clothes. Until your toddler has developed their static balance control, they will be unable to hold their balance for longer periods of time [2]
Postural control
The way our central nervous system manages sensory input in order to create enough motor response to maintain a controlled, upright posture is referred to as postural control. Being able to stand on one leg and to hop requires many different systems and cognitive processes to be in place in order to execute this successfully.
Sensory information from the vestibular system works in harmony with the brain to provide the body with a sense of balance and hold it upright. Information from proprioception, which senses movement, is required to detect leg movements and sway which then stabilise postural control and coordination. [3]
Other factors for maintaining balance
Your toddler will now be managing all kinds of other factors as they learn to stand on one leg and hop. Their brain will be beginning to understand how their body will move and how their other limbs will behave when one is temporarily lifted from the floor. This means that they need to assess their space and be able to adjust their bodies in order to remain upright.
Their muscles are now becoming stronger in order to support their weight on one leg, and they will require additional strength to generate power when jumping into the air. Their muscles will be put to the test when exerting force on the leg that remains on the ground.
What next
It will take some time for your toddler to maintain balance on one leg. With lots of practice, they will be able to hold their balance for longer periods of time.
References:
[1] S. Goddard Blyth (2017). Attention, Balance and Coordination The A.B.C. of Learning Success: Second Edition. Wiley Blackwell
[2] M. Henry and S. Baudry (2019). Article: Control of Movement: Age-related changes in leg proprioception: implications for postural control. Journal of Neurophysiol. 2019 Aug 1; 122(2): 525–538. Published online 2019 Jun 5. doi: 10.1152/jn.00067.2019
[3] Adolph, K. E. & Berger, S. E. (2015). Physical and motor development. In M. H. Bornstein & M. E. Lamb (Eds.), Developmental science: An advanced textbook, (7th ed., pp. 261-333). New York: Psychology Press/Taylor & Francis.