The Arm Posture Score for assessing arm swing during gait: An evaluation of adding rotational components and the effect of different gait speeds

- Comprehensive measures of arm swing during gait are lacking.
- The Arm Posture Score (APS) has been proposed, but not evaluated regarding speed.
- APS was quantified in non-disabled adults walking at self-selected and slow speed.
- Speed condition (whether self-selected or slow) had an impact on the APS.
- Consider gait speed when APS measures are used for assessing arm swing during gait.

In 3D gait analysis, quantification of leg movements is well established, whereas a measure of arm swing has been lacking. Recently, the Arm Posture Score (APS) was introduced to characterize arm movements in children with cerebral palsy, including information from four variables (APS4) in the sagittal and frontal planes. A potential limitation of the APS is that it does not include rotational movements and has not yet been evaluated with regard to gait speed. The aims of this study were (i) to investigate the effect on APS of adding two components of arm rotation (APS6) and (ii) to determine the influence of gait speed on the APS measures, when applied to non-disabled adults. Forty-two subjects walked 10 m at a self-selected speed (1.34 m/s), and in addition a subgroup of 28 subjects walked at a slow speed (0.66 m/s) set by a metronome. Data were collected from markers in a whole-body set up and by eight optoelectronic cameras. The results demonstrated significantly higher APS6 than APS4 values for both arms, irrespective of gait speed. Speed condition, whether self-selected or slow, had a significant effect on both APS measures. The two additional arm components are suggested to provide relevant information about arm swing during walking. However, APS6 needs to be implemented in gait analysis of individuals with gait arm pathologies in order to further examine its utility. We recommend that gait speed should to be taken into account when using APS measures to quantify arm swing during gait.