The association between cardiac autonomic system function at the entrance to rehabilitation and walking-endurance two months later among children following-ABI.

Background: The cardiac autonomic control system function is frequently impaired after brain injury. An association exists between the cardiac autonomic control system and endurance performance.

Aim: To evaluate the association between cardiac autonomic control system indices at the beginning of the inpatient rehabilitation and walking endurance two months later among children and adolescents following acquired brain injury.

Methods: A prospective study included 28 children and adolescents following acquired brain injury in the sub-acute phase. A Polar device (RS800CX) records heart rate as a proxy measure of autonomic function at sitting and lying supine on admission and two months later. The 6-minute walk test was assessed at the second assessment in 25 participants. Non-parametric tests were used with statistical significance defined as p < 0.05.

Results: There were statistically significant differences in heart rate variability between lying and sitting positions, which were positively correlated with the 6-minutes walk test results two months later, mainly in the parasympathetic components (r = 0.51 p-value <0.01).

Conclusions: At the beginning of the rehabilitation of children and adolescents following acquired brain injury, a simple manipulation - position change from sitting to lying, activates cardiac autonomic control system responses. These responses are positively associated with walking endurance two months later.