Synergies analysis produces consistent results between motion analysis laboratories

Aim: The dynamic motor control index during walking (walk-DMC) is a scaled measure of motor control derived from electromyographic analysis of the lower extremity during gait. Walk-DMC has been shown to be related to patient outcomes and there has been an increasing interest from motion analysis centers regarding using this metric in their own practice. However, the methods for computing the index reported in the literature are not consistent. Here we propose a standardized method and investigate if this leads to results that are consistent between laboratories. Method: Comparisons between three sets of typically developing controls contributed by three independent motion analysis centers are made. Comparisons are also made between the proposed and previously published methods. A program script to compute the walk-DMC was used for this study and is made freely available with this manuscript. Results: Using this script, results are highly consistent between three participating centers. The currently proposed method results in a wider distribution of walk-DMC values than those previously reported. Interpretation: Using consistent processing methods, synergy measures are equivalent between centers. The major differences between current and published data are attributed to the use of concatenation of several walking trials.