Abstract
BACKGROUND & AIM: Reduced vestibular function increases fall risk (Agrawal et al. 2012). Noise exposure (NE) can lead to otolith damage (Stewart et al. 2020), yet can be overlooked as a source of vestibular deficit and thus fall risk (e.g., Picard et al. 2008; Girard et al. 2014). To date, little is known about the effects of NE on gait. The aim of this study was to investigate how lifetime NE may change gait characteristics across the life span.
METHODS: To assess lifetime NE, participants completed the Noise Exposure Structured Interview (NESI, Guest et al. 2018). 25 (9M) participants had low and 22 (16 M) had high (logNESI ≥ 1) lifetime NE. Mobility was assessed using a clinical timed up and go (cTUG). Stride cycles were extracted from straight phases of the instrumented TUG (iTUG, 3 m) and ellipsoid (4 m) walking tasks (Agathos et al. 2023). Movements were recorded using 6 IMUs placed on the back of the head, chest (used to estimate trunk motion), back (~L4), and 2-3 cm above each ankle, with one IMU placed on the floor for reference (N=XX) or with 3 IMUs placed on the head, chest, and right leg as above (N=YY). Stride duration, stride length, and stride speed were averaged from all available cycles for each participant. Subsequently, all cycles were aligned on cycle start and samples at matching time points were averaged. Peak power/frequency and peak sway times/amplitudes, as well as angular head and trunk velocities/rotation angles (pitch, roll, yaw) and linear accelerations/displacements in mediolateral (ML), anteroposterior (AP) and vertical (Z) directions were extracted from these cycle averages. We also calculated head-trunk delays and anchoring indices. In total, 146 gait features were evaluated as a function of age and NE group (simple model), or also including cTUG times and participant height (full model), using robust linear regression modeling.
RESULTS: To look at the effects of NE on age-related gait changes, we selected gait features that showed a significant interaction between age and NE group in one or both models (22 gait features). 9 were trunk-related: pitch angular velocity maximum/range and peak power frequency; yaw angular velocity peak amplitude/time ; peak Z acceleration; pitch and yaw maximum angle; and roll angle extremum time. 8 were head-related: yaw angular velocity range, extremum/timing ; time of min Z linear acceleration; pitch angle peak power frequency; yaw angle range, maximum/timing. 5 were delays between head and trunk in pitch angular velocity, ML and Z linear acceleration, and pitch and roll angle. Only 2 features were better represented by the full model (time of minimum head Z linear acceleration and peak power frequency of the trunk pitch angular velocity).
CONCLUSIONS: In those with high NE, affected gait characteristics were similar to older non-exposed individuals at younger ages. Our findings suggest that vestibular changes due to NE may have similar effects on gait as those due to normal aging.