Effects of cognitive- and motor-dual tasks on postural control regularity following anterior cruciate ligament reconstruction.

The study analysed 14 matched pairs, so the results may not be stable across larger groups. The data were a secondary analysis of a study designed to examine traditional linear balance measures, not the sample entropy outcome used here. No a priori power analysis was possible; a post-hoc estimate gave 86% power for detecting a group-by-condition interaction with 14 matched pairs. The ACLR group was a convenience sample from a university setting, so it may not represent all people after ACL reconstruction. The cognitive task was not scored, so it is unknown whether cognitive performance was sacrificed during the balance trial. Healthy controls were clustered near the ceiling of the patient-reported outcome measures, so correlations were analysed only in the ACLR group. Interpreting lower sample entropy as less automatic, less healthy postural control is simplified because there may be an upper limit of irregularity that is still healthy. Participants were told to stand as still as possible, which may have reduced natural automatic postural control. The sample entropy template length m = 3 corresponds to about 60 msec and may miss longer time-scale contributions to balance control. The cognitive numbers were presented visually, which may have created a visual anchoring effect on balance.

The authors declared no conflicts of interest. The article is categorized as Research Support, Non-U.S. Gov't.

Do not conclude that adding cognitive dual-task training to ACL reconstruction rehabilitation improves outcomes. This study compared balance patterns between groups and did not test an intervention, and the association with sport function does not show that changing balance regularity causes better or worse recovery.