title: Interaction between force production and cognitive performance in humans.
abstract: OBJECTIVE
  A dual task paradigm was used to examine the effects of the generation of force on cognitive performance.
  
  
  METHODS
  Subjects (n=22) were asked to respond to auditory stimuli with their left middle or index finger and concurrently maintain a sub-maximal contraction with their right index finger at one of two different force levels. The contraction was maintained for approximately 12s and the target force level was alternated between 30 and 60% of the maximal force. Force production was the primary task of interest; performance of the (secondary) choice reaction time task (reaction times and accuracy) was used as an index of the amount of interference between the two tasks.
  
  
  RESULTS
  All subjects were capable of performing the force tasks adequately. Significant interference was observed between the level of force production and cognitive performance. At the higher force level, subjects performed the cognitive task more slowly and less accurately compared to the lower force level.
  
  
  CONCLUSIONS
  Our results show that the execution of high-effort motor behaviour interacts with cognitive task performance. However, comparison with the data obtained during fatiguing contractions in a previous study [Lorist MM, Kernell D, Meijman TF, Zijdewind I. Motor fatigue and cognitive task performance in humans. J Physiol 2002;545:313-319.] showed that the interference was stronger during fatiguing contractions than during the present high-effort motor behaviour.
  
  
  CONCLUSIONS
  The results suggest that force-related factors can explain part of the fatigue-related interference between force production and cognitive performance. This result could have consequences for interpreting cognitive deficits observed in patients suffering from motor dysfunction.
authors.affiliation: Department of Medical Physiology, University Medical Center Groningen, A. Deusinglaan 1, P.O. Box 196, 9700 AD Groningen, The Netherlands. i.zijdewind@med.rug.nl
authors.forename: Inge
authors.initials: I
authors.lastname: Zijdewind
authors.forename: Hiske
authors.initials: H
authors.lastname: van Duinen
authors.forename: Ronald
authors.initials: R
authors.lastname: Zielman
authors.forename: Monicque M
authors.initials: MM
authors.lastname: Lorist
mesh_terms: D000161:Acoustic Stimulation / Q000379:methods; D000328:Adult; D000704:Analysis of Variance; D002755:Choice Behavior / Q000502:physiology; D003071:Cognition / Q000502:physiology*; D004576:Electromyography / Q000379:methods; D005260:Female; D005385:Fingers / Q000294:innervation; D018737:Hand Strength / Q000502:physiology*; D006801:Humans; D008297:Male; D011597:Psychomotor Performance / Q000502:physiology*; D011930:Reaction Time / Q000502:physiology; D013647:Task Performance and Analysis; D013997:Time Factors