INTEREST OF GAIT VARIABILITY ANALYSES AMONG HEALTHY SUBJECTS AND PARKINSO- NIAN PATIENTS

Lejeune, Thierry [UCL]

In addition to reduced gait speed, shorter stride length and stooped posture, typical gait disorders in Parkin- son’s disease (PD) are characterized by postural and gait instability, which can lead to an increased fall risk. A higher fall risk has typically been associated with a lack of adaptive gait control in the presence of sensorimotor variability or external disturbances. us, detection of speci c markers of gait instability appears critical for preventing falls and their consequences. Gait variables from standard three-dimensional quanti ed walking analyses do not constitute adequate pre- dictors of falls. However, temporal organization of stride duration variability has recently been mentioned as a good candidate from which to derive markers of gait instability as it is tightly linked to rhythm control, which is particularly impaired in PD. Indeed, stride duration uctuates in a structured, complex manner over the long term (hundred of gait strides), displaying the presence of long-range autocorrelations (LRA) that can span hundreds of consecutive strides. LRA result from the memory of the preceding values in the series, highlighting the existence of a complex temporal structure in human locomotion. Interestingly, recent studies claimed that the temporal organization of variability (i.e., LRA) would represent the signature of adaptive abilities of healthy systems and their breakdown an index of pathological condition. By extension, the degradation of LRA with pathology was associated to dynamic instability in locomotion. However, no studies have included the analysis of LRA in the functional assessment of pathological gait. e interest of studying the gait variability on long series of stride with non linear mathematics will be presented, as well as their complementarity will short series classical methods (coe cient of variation). E ects of age, gait speed and terrain will be discussed.