Reproducibility of spatio-temporal gait parameters under different conditions in older adults using a trunk tri-axial accelerometer system.

The aim of this study was to determine intra- and interrater reliability of spatio-temporal gait parameters on different walking surfaces and under dual task conditions in an older adult population using a trunk tri-axial accelerometer (DynaPort((MiniMod)) system. Twenty-three independent living, older subjects (8 males, 15 females) aged 73.4+/-4.3 years walked three times at their preferred walking speed in two test sessions under four different conditions over 24 m (gymnasium floor versus soft foam rubber walkway, with both normal and dual task walking conditions). Inter- and intrarater reliability was assessed. Subsequently intraclass correlation coefficients (ICC), coefficients of variation (CV) and ratios limits of agreement (RLOA) were calculated. The reliability of walking speed, cadence, step duration and step length was excellent with high ICCs and small CVs and RLOAs. ICCs of gait variability ranged from 0.12 to 0.88. The corresponding CVs ranged from 12% to 34% and RLOAs from 35% to 93% and appeared relatively large. The results of this study demonstrate that walking speed, cadence, step duration and step length under more challenging conditions can be reliably measured in independent living older adults using the DynaPort(MiniMod) system. Gait variability measures need to be viewed with caution and further research in older populations is needed to determine the value of these parameters derived from this measurement system.