The mental representation of the human gait in young and older adults

Abstract

The link between mental representation (MREP) structures and motor performance has been evidenced for a great variety of movement skills, but not for the human gait. Therefore the present study sought to investigate the cognitive memory structures underlying the human gait in young and older adults. In a first experiment, gait parameters at comfortable gait speed (OptoGait) were compared with gait-specific MREPs (structural dimensional analysis of MREP; SDA-M) in 36 young adults. Participants were divided into a slow- and fast-walking group. The proven relationship between gait speed and executive functions such as working memory led to the hypothesis that gait pattern and MREP differ between slow- and fast-walking adults. In a second experiment, gait performance and MREPs were compared between 24 young (27.9 years) and 24 elderly (60.1 years) participants. As age-related declines in gait performance occur from the seventh decade of life onward, we hypothesized that gait parameters would not be affected until the age of 60 years accompanied by unchanged MREP. Data of experiment one revealed that gait parameters and MREPs differed significantly between slow and fast walkers. Notably, eleven previously incurred musculoskeletal injuries were documented for the slow walkers but only two injuries and one disorder for fast walkers. Experiment two revealed no age-related differences in gait parameters or MREPs between healthy young and older adults. In conclusion, the differences in gait parameters associated with lower comfortable gait speeds are reflected by differences in MREPs, whereby SDA-M data indicate that the single limb support phase may serve as a critical functional period. These differences probably resulted from previously incurred musculoskeletal injuries. Our data further indicate that the human gait and its MREP are stable until the age of 60. SDA-M may be considered as a valuable clinical tool for diagnosis of gait abnormalities and monitoring of therapeutic effectiveness.

Keywords: aging; long-term memory; normal and pathological gait; structural dimensional analysis of mental representation (SDA-M).

FIGURE 1

Functional divisions of the gait cycle according to Perry and Burnfield (2010).

FIGURE 2

Screenshot of the splitting procedure. One picture was presented in the anchoring position (top picture in the middle column as indicated by a red rectangle) to which participants classified the remaining N-1 pictures (presented in the lower half of the middle comlumn as indicated by a yellow rectangle) as similar (left column) or dissimilar (right column) to the anchoring picture.

FIGURE 3

Mean group dendograms for (A) slow-walking adults, (B) fast-walking adults, (C) healthy young adults and (D) healthy older adults. The y-axis displays the euclidean distance. The horizontal line marks d_crit for a given α-level (d_crit = 3.53; α = 0.050). The x-axis shows the BACs (basic action concepts): (1) initial contact, (2) loading response, (3) mid stance, (4) terminal stance, (5) pre-swing, (6) initial swing, (7) mid swing.