Differences in whole-body angular momentum between treadmill and overground walking

Whole-body angular momentum (H) is a relevant biomechanical marker of dynamic balance during walking. Although treadmill walking is commonly used for gait analysis and rehabilitation, it results in notable spatiotemporal and kinetic differences compared to overground walking. However, its specific effects on H remain unclear. This study aimed to investigate differences in H between treadmill and overground walking in able-bodied adults. Fourteen healthy adults walked at their preferred speed under two randomized conditions: 1) treadmill walking and 2) overground walking on a 7-meter walkway. H was computed in the sagittal, frontal, and transverse planes using 3D motion capture data. Amplitude (peak-to-peak range) and temporal evolution of H were analyzed and compared across walking conditions. Spatiotemporal gait parameters were also calculated. Compared to overground walking, treadmill walking was associated with a significantly reduced H range (p < 0.001) and an altered temporal evolution of H across all planes. These alterations were accompanied by spatiotemporal modifications, including increased cadence and step width, as well as reduced step length and stride length during treadmill walking. These changes may reflect a more conservative gait strategy to enhance balance control during treadmill walking. These findings highlight that H differs between treadmill and overground walking, and that caution should be exercised when generalizing results obtained on the treadmill to overground walking.