This study aimed to examine the effects of age and the task difficulty on postural sway, variability and complexity. The participants were 90 able-bodied individuals including children ( n = 39; age: 5.89 ± 0.94 years), young adults ( n = 30; age: 23.23 ± 1.61 years) and older adults ( n = 21; age: 64.59 ± 5.24 years) who took part in different balance tasks that had different levels of cognitive and physical challenges. The main dependent variables were postural sway area, postural variability and postural complexity. The participants stood on a standard force plate for 10 s in each task condition, and the centre of pressure displacement was collected at 100-Hz sampling frequency. The results of this study showed that children and older adults, in the more difficult tasks, had greater sway area and complexity and less postural variability. In addition, there was a linear trend in the stability measures as the difficulty of the task was increased. In conclusion, special populations, such as children and older adults, were more sensitive to the balance changes and used active control mechanisms to minimise the risk of losing balance in more challenging conditions.

Effects of a developmental task constraints intervention on kinematic synergies during two-hand catching in children with developmental delays.

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