EFFECTS OF LATERAL STEPPING GAIT AND DUAL TASKING DURING TREADMILL WALKING IN HEALTHY YOUNG AND OLDER ADULTS.

Previous studies on lateral stepping gait have demonstrated decreased variability and also decreased involvement of central nervous system's active control in the direction of progression. This study sought to further explore this notion through the variability of stride interval time series (SIT) and signal magnitude difference time series (SMD) while forward and lateral walking using an inertial sensor mounted at the sternum. Additionally, this study also explored the effects of dual-tasking on forward and lateral walking variability. Seven young (age 22.6±2.5 years) and seven old participants (age 71.14±6.5 years) were recruited for this study. Participants performed forward and lateral walking on treadmill at their preferred speed with and without dual tasking. The dual task provided was a mental arithmetic task (counting backwards from a random provided number by subtracting the number three). We found that complexity of stride interval time series decreased significantly during lateral walking in both young and older adults (p=0.01). We also found lateral walking affected both young and elderly and the complexity of signal magnitude differences in angular velocity signals reduced (p=0.01) than that at forward walking. We also found significant interaction effects in complexity of SMD signals between direction of progression and age groups. Furthermore, it was also found that dual-tasking affected both forward and lateral walking and both age groups by decreasing fractal properties in SMD (p=0.02). This study explored the complexity (approximate entropy and multiscale entropy) of temporal structure of movement as well as magnitudes of angular velocities and found that there is loss of complexity in both young and older adults due to lateral walking. We also found dual-tasking induced anti-persistence in angular velocities.