title: Postural control as a function of time-of-day: influence of a prior strenuous running exercise or demanding sustained-attention task.
abstract: BACKGROUND
  The current experiment investigated the impact of two potential confounding variables on the postural balance in young participants: the induced-experimental activity prior to the static postural measurements and the well-documented time-of-day effects. We mainly hypothesized that an exhaustive exercise and a high attention-demanding task should result in alterations of postural control.
  
  
  METHODS
  Ten participants performed three experimental sessions (differentiated by the activity - none, cognitive or physical - prior of the assessment of postural stability), separated by one day at least. Each session included postural balance assessments around 8 a.m., 12.00 p.m. and 5 p.m. ± 30 min. The physical and cognitive activities were performed only before the 12 o'clock assessment. The postural tests consisted of four conditions of quiet stance: stance on a firm surface with eyes open; stance on a firm surface with eyes closed; stance on a foam surface with eyes open and stance on a foam surface with eyes closed. Postural performance was assessed by various center of pressure (COP) parameters.
  
  
  RESULTS
  Overall, the COP findings indicated activity-related postural impairment, with an increase in body sway in the most difficult conditions (with foam surface), especially when postural measurements are recorded just after the running exercise (physical session) or the psychomotor vigilance test (cognitive session).
  
  
  CONCLUSIONS
  Even if no specific influence of time-of-day on static postural control is demonstrated, our results clearly suggest that the activities prior to balance tests could be a potential confounding variable to be taken into account and controlled when assessing clinical postural balance.
authors: University of Nantes, Laboratory Motricité, Interactions, Performance (EA 4334), F-44000, Nantes, France. thibault.deschamps@univ-nantes.fr
authors: Thibault
authors: T
authors: Deschamps
authors: Justine
authors: J
authors: Magnard
authors: Christophe
authors: C
authors: Cornu
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001143:Arousal / Q000502:physiology; D001288:Attention / Q000502:physiology*; D001696:Biomechanical Phenomena; D002940:Circadian Rhythm / Q000502:physiology*; D003071:Cognition / Q000502:physiology; D003627:Data Interpretation, Statistical; D005260:Female; D006801:Humans; D008297:Male; D004856:Postural Balance / Q000502:physiology*; D011597:Psychomotor Performance / Q000502:physiology; D011930:Reaction Time / Q000502:physiology; D012420:Running / Q000502:physiology*; D055815:Young Adult