Cognitive load affects lower limb force-time relations during voluntary rapid stepping in healthy old and young adults

J Gerontol A Biol Sci Med Sci. 2010 Apr;65(4):400-6. doi: 10.1093/gerona/glp185. Epub 2009 Nov 25.


Background: Quick step execution may prevent falls when balance is lost; adding a concurrent task delays this function. We investigate whether push-off force-time relations during the execution of rapid voluntary stepping is affected by a secondary task in older and young adults.

Methods: Nineteen healthy older adults and 12 young adults performed rapid voluntary stepping under single- and dual-task conditions. Peak power, peak force, and time to peak force during preparatory and swing phases of stepping were extracted from center of pressure and ground reaction force data.

Results: For dual-task condition compared with single-task condition, older adults show a longer time to reach peak force during the preparation and swing phases compared with young adults (approximately 25% vs approximately 10%, respectively). Peak power and peak force were not affected by a concurrent attention-demanding task.

Conclusion: Older adults have difficulty allocating sufficient attention for fast muscle recruitment when concurrently challenged by an attention-demanding task.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Accidental Falls*
  • Adult
  • Aged
  • Aged, 80 and over
  • Aging / physiology*
  • Attention / physiology
  • Cognition / physiology*
  • Gait / physiology*
  • Humans
  • Postural Balance / physiology*
  • Reaction Time