Kinematic analysis of speed transitions within walking in younger and older adults

Abstract

The ability to adapt to environmental and task demands while walking is critical to independent mobility outside the home and this ability wanes with age. Such adaptability requires individuals to acutely change their walking speed. Regardless of age, changes between walking speeds are common in daily life, and are a frequent type of walking adaptability. Here, we report on older and younger adults when transitioning from preferred walking speed overground to either slower or faster walking. Specifically, we evaluated biomechanical parameters prior to, during, and post transition. Individuals approached the walking speed transition similarly, independent of whether the transition was to slower or faster walking. Regardless of age or walking speed, the step during which a walking speed transition occurred was distinct from those prior- and post- transition, with on average 0.15 m shorter step lengths, 3.6° more hip flexion, and 3.3° more dorsiflexion during stance. We also found that peak hip flexion occurred 22% later, and peak hip extension (39%), knee flexion (26%), and dorsiflexion (44%) occurred earlier in stance for both typical to slower and typical to faster walking. Older adults had altered timing of peak joint angles compared with younger adults across both acceleration and deceleration conditions, indicating age-dependent responses to changing walking speed. Our findings are an important first step in establishing values for kinematics during walking speed transitions in younger and typical older adults.

Keywords: Aging; Gait; Kinematics; Mobility; Speed transition.

Fig. 1.

Graphical representation of hypothesized changes in spatiotemporal variables and joint angles across all phases of the transition (during-transition step shown by the dashed line) for preferred speed to slower (Normal-Slow) and preferred speed to faster (Normal-Fast) walking in younger adults (blue) and older adults (orange). Arrows indicate pre- to post- direction, while “smaller” and larger” indicate relative variable magnitude. The pre-post range in variable magnitude is highlighted by box size. Anticipated age-related differences are indicated by horizontal differences in either end of the highlighted box, which would indicate a difference in pre- or post- values across age groups, or by the dashed lines being horizontally offset, indicating the during-transition step value being different across age groups. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)

Fig. 2.

Schematic of procedure to determine the point of transition. Forward center of mass (CoM) velocity trace with graphical representation of user-selected range (yellow box) and mathematically identified transition point (red cross), with corresponding left (green) and right (red) steps depicted. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)