Learning new gait patterns: Age-related differences in skill acquisition and interlimb transfer

Abstract

Evidence from upper-extremity literature suggests that the normal ageing process affects an individual's ability to learn and retain a motor skill, but spares their ability to transfer the skill to the untrained, opposite limb. While this phenomenon has been well-studied in the upper-extremity, evidence in the lower-extremity is limited. Further, it is unclear to what extent age-related differences in motor learning and transfer are dependent on visual feedback of the motor task. Therefore, the purpose of this study was to examine the effects of ageing on motor learning, retention, and interlimb transfer during walking with and without visual feedback. Forty-four subjects (24 young; 20 older adults) were tested on a treadmill over two consecutive days. On day 1, subjects learned a new gait pattern by performing a foot-trajectory tracking task that necessitated greater hip and knee flexion during the swing phase of the gait. On day 2, subjects repeated the task with their training leg to test retention, then with their untrained leg to test interlimb transfer. Trials without visual feedback were also collected on both days. Results indicated that older adults had reduced ability to learn the task, and also exhibited lower retention and inter-limb transfer. However, these differences were dependent on visual feedback as the groups performed similarly when feedback was removed. The findings provide novel evidence indicating that ageing impairs learning, retention, and transfer of motor skills in the lower-extremity during walking, which may have implications for gait therapy after stroke and other geriatric conditions.

Keywords: Adaptation; Ageing; Consolidation; Elderly; Functional task.

Figure 1:

(A) Schematic of the experimental protocol. Target-match trials indicate training blocks where participants performed a foot-trajectory tracking task while receiving visual feedback, and no vision trials indicate blocks in which participants performed the tracking task without any visual feedback. Pre and Post refers to the initial and final training blocks. Following each block, subjects were given approximately one minute of rest. (B) Schematic of the experimental variables and statistical comparisons used to test age-related differences in motor learning, retention, and interlimb transfer. The left column indicates the blocks that were used as covariates in the analyses and the right column indicates the blocks that were compared between the groups.

Figure 2:

(A) Schematic showing the setup used for the continuous skill learning task during walking. (B) Schematic depicting construction of the target template. (C) Schematic showing the computation of tracking error (shaded region).

Figure 3:

Mean tracking error in older and young adults for each target-matching (TM) block on (A) Day 1 with the training leg (Tr₁), (B) Day 2 with the training leg (Tr₂), and (C) Day 2 with the transfer leg (Tf). Error bars represent the standard error of the mean.

Figure 4:

Improvements in tracking error during the various components of learning and interlimb transfer in older and young adults. Bars represent the marginal means of the change in tracking error and error bars represent standard error of the mean. Positive values indicate a reduction in tracking error. Asterisks indicate a significant difference between older and young adults (p < 0.05).

Figure 5:

Mean tracking error in the training (Tr) and transfer (Tf) legs during no visual feedback (NV) trials in older and young adults. Breaks in the x-axis indicate that there was a change in the day or the leg that was performing the task. Error bars represent the standard error of the mean.