Effects of age on relationships between trunk kinematics and centre of mass motion in the frequency domain during gait

Abstract

Previous work has analyzed biomechanical signals in the frequency domain, although primarily during quiet standing tasks. To the author’s knowledge, no previous research has examined the relationship between trunk kinematics and extrapolated centre of mass motion in the frequency domain during treadmill walking throughout adulthood. The purpose of this study was to use coherence to quantify relationships between trunk angles and extrapolated centre of mass motion during gait; and to determine if there were any age-related differences in these relationships. To explore this purpose, 60 participants (split into 6 groups by decade) ranging from 22-79 years of age completed 400 steps at two walking speeds on a treadmill while motion capture data was recorded. These data were used to calculate trunk segment angles (flexion-extension, lateral bend) and extrapolated center of mass position (anteroposterior, mediolateral). Coherence analysis was used to examine the relationships between all pairings of these signals at various frequencies of interest; coherence values were then compared between frequencies of interest and age groups. Significant effects of frequency on coherence values were observed for all signal pairings. The strongest coherence values occurred for pairings of signals in the same plane, and at the primary frequency mode for that plane. Significant age effects were only seen for the pairing of trunk flexion-extension and anteroposterior extrapolated centre of mass position; however, the trends in the coherence values reflected those for mean walking speed, which warrants further investigation. These findings provide insight into the dominant frequencies in each direction during gait, and the influence of these dominant frequencies on coherence. This study will be used to inform future research extending the current analysis from trunk kinematics to lower extremity joint kinematics.