Falls are the leading cause of nonfatal injuries in children and elderly. To understand the causes of falling in these populations, fundamental knowledge of how ageing affects balance control is of utmost importance.

In general, two biomechanical mechanisms allow people to control balance; 1.moving the center of pressure within the base of support using ankle muscle activation; 2.counter-rotating segments around the center of mass. To understand how balance is controlled differently across the lifespan, 4 age groups (each N=20) will be compared to each other; i.e. prepubertal children (6-9y), postpubertal children (15-17y), young adults (18-24y), healthy non-falling older adults (65-80y). .

A force plate platform combined with 3D movement registration will be used to determine the biomechanical balance control strategy across the lifespan during unperturbed and perturbed standing. The innovative but focused scope of this study could provide a breakthrough in our biomechanical understanding of balance control and, in particular, the changes in limitations of balance control in childhood and an ageing (fall-prone) population. The gained fundamental knowledge could lead to unprecedented insights in the causes of falling across the lifespan and in possible targets for intervention.

Inclusion Criteria:

• prepubertal children (6-9y)
• postpubertal children (15-18y)
• young adults (18-24y)
• healthy non-falling older adults (65-80y) will be included if they 1) did not experience two or more falls during normal daily activities in the preceding year and 2) have no cognitive impairment (tested with Mini-Mental state examination).

Exclusion Criteria:

1. inability to speak and understand Dutch;
2. inability to maintain independent unsupported stance for 60 seconds;
3. current diagnosis of neurological or sensory disorders;
4. recurrent dizziness;
5. obesity ;
6. a history of orthopaedic disorders;
7. surgical operation of the lower extremity during last two years;
8. use of drugs affecting the CNS or known to affect balance control.