Investigating the relationship among conscious motor processing, attentional focus and walking performance by older adults

Abstract

Shifting attention towards movement mechanics or greater internal awareness of movement (i.e., reinvestment or an internal attentional focus) may result in compromised motor performance through the disruption of movement automaticity. However, it has yet to be determined how this specifically leads to behavioral disturbance of locomotion that correlates with the risk of falling in aging population. This thesis aimed to address how reinvestment – manipulated by attentional focus – affects walking performance in terms of gait stability and neuromuscular efficiency in older adults. Concurrently, this thesis also examined a prospective maneuver (i.e., an external attentional focus) that could potentially modulate the effect of reinvestment, which in turn encourages the potential to reduce the possibility of future falls.

Five studies are presented in this thesis to investigate the relationship among conscious motor processing, attentional focus and walking performance in older adults. In the first study (Chapter Two), poorer gait stability and greater body sway were demonstrated when an internal attentional focus instruction was given compared to external attentional focus or control conditions among community-dwelling older adults. In the second study (Chapter Three), it was further shown that an internal attentional focus instruction induced conservative gait adaptations (indicative of increased fall-risk) in older adults with low trait reinvestment propensity compared to a control condition. Neuromuscular efficiency during walking was investigated among older adults in relation to fall risk in the third study (Chapter Four). Higher lower limb muscle co-contractions (indicative of reduced movement efficiency) were observed in older fallers when given an internal attentional focus instruction compared to an external attentional focus condition. Subsequently, to justify the assumption that there are changes in cognitive effort/involvement of conscious control that presumably links with performance in previous studies, the fourth and fifth studies (Chapters Five and Six) aimed at quantitatively measuring the degree of real-time conscious motor processing among different attentional focus conditions during different walking tasks in older adults. The fourth study demonstrated a lack of significant changes among control, internal and external attentional focus conditions in a simple, level-ground walking task. The fifth study, a modification of the fourth one, then illustrated an increased real-time conscious motor processing in a more challenging walking task (i.e., walking on foam surface) compared to the level-ground walking task. Furthermore, an external attentional focus instruction was shown to reduce conscious involvement of motor processing in conjunction with increasing movement ‘fluency’ (i.e., faster gait) under the challenging walking task.

In conclusion, this thesis presented evidence that shows an internal attentional focus compromises gait performance in community-dwelling older adults during a level-ground walking task. On the contrary, an external attentional focus manipulation appears to improve gait performance through reducing conscious involvement during a challenging walking task among older adults. While the current findings practically suggest that healthcare practitioners might exercise caution when applying internal focus instructions to patients in clinical rehabilitation settings, they provide encouragement for the advocacy of external focus instructions in planning rehabilitation gait training that prepares older adults for overcoming movement challenges during gait in daily life.