Compare the effects of cognitive task on older community fallers and non-fallers in stepping down activity

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Compare the effects of cognitive task on older community fallers and non-fallers in stepping down activity

 

Author: Lee, Yin-tak
Title: Compare the effects of cognitive task on older community fallers and non-fallers in stepping down activity
Degree: M.Sc.
Year: 2006
Subject: Hong Kong Polytechnic University -- Dissertations
Falls (Accidents) in old age -- Prevention
Exercise for older people
Department: Dept. of Rehabilitation Sciences
Pages: xi, 56 leaves : col. ill. ; 30 cm.
InnoPac Record: http://library.polyu.edu.hk/record=b1968137
URI: http://theses.lib.polyu.edu.hk/handle/200/5451
Abstract: Recent studies have shown that older adults employ a strategy of elevated muscles pre-activity (pre-landing muscle activity) of lower limb in stepping down when compared with that of young people. The possible reason of the strategy is to stiffen the lower limb joints for better postural stability so as to compensate the deterioration of neuromuscular control due to aging. However, whether there is a different between older fallers and non-fallers, and whether a concurrent cognitive task would affect the pre-landing muscle activity are unknown. The aims of this study were to determine whether there was a difference of pre-landing muscle activities between older fallers and non-fallers, and whether a concurrent cognitive task would affect the pre-landing muscle response latencies. In this study, 10 older subjects with history of falls (mean age = 72.0 ± 5.0 years) and 9 non-fallers serving as control (mean age = 72.1 ± 7.3 years) were recruited. Pre-landing muscle response latencies of tibialis anterior (TA) and medial gastrocnemius (MG) were recorded using EMG on stepping down alone (single task) and stepping down with a concurrent cognitive activity (dual tasks). Subjects underwent concurrent cognitive task through naming of vegetables and fruits before the starting of downward stepping.
Our result demonstrated that fallers showed a trend of longer pre-landing muscle response latency of TA muscles during stepping down when compared with non-fallers (141.1 ± 58.1 ms and 110.9 ± 68.2 ms, respectively; P= 0.3 12). When a concurrent cognitive task was added during downward stepping, the pre-landing muscle response latencies at the TA muscles were significantly shortened in the fallers than non-fallers (44.4% and 15.6% decreased, respectively; P = 0.033). This study shows that fallers exhibited a larger disturbance in the pre-landing muscle response latencies than non-fallers during stepping down when they underwent the dual-task paradigm. This may affect their compensation strategy of stiffen up of ankle joint as commonly adopted by older adults and causes falls.

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