Effects of concurrent cognitive task on pre-landing muscle response latency during stepping down activity in older adults with and without a history of falls

Wai Nam Tsang, Ken Y T Lee, Siu Ngor Fu

Research output: Journal article publicationJournal articleAcademic researchpeer-review

4 Citations (Scopus)


Purpose. To investigate the co-contraction of ankle muscles in older subjects with and without a history of falls during a stepping down activity, and whether the co-contraction was disrupted by a concurrent cognitive task. Method. Ten fallers and 9 non-fallers (mean age = 72.0 ± 5.0 and 72.1 ± 7.3 years, respectively) were recruited. Electromyography (EMG) of the tibialis anterior (TA) and medial gastrocnemius (MG) was recorded during stepping down with and without a concurrent cognitive task. Co-contraction was investigated using the time between the EMG onset and the foot touching a force-platform, termed the pre-landing muscle response latency. Results. The fallers showed longer pre-landing muscle response latencies in the TA compared with non-fallers (141.1 ± 58.1 ms and 110.9 ± 68.2 ms, respectively). With a concurrent cognitive task, the pre-landing muscle response latencies in the TA were shortened in fallers significantly more than in non-fallers (44.4% and 15.5%, respectively). No significant difference in MG activation was found between 2 groups in the stepping down activity with and without cognitive task. Conclusions. Subjects with history of falls exhibit a greater shortening in the pre-landing muscle response latency than non-fallers when distracted during stepping down. Disruption of their co-contraction in ankle joint might precipitate such older adults to fall.
Original languageEnglish
Pages (from-to)1116-1122
Number of pages7
JournalDisability and Rehabilitation
Issue number15
Publication statusPublished - 22 Sep 2008


  • Co-contraction
  • Compensation strategy
  • Dual tasks
  • Fallers

ASJC Scopus subject areas

  • Rehabilitation
  • Health Professions(all)

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