title: Effect of unilateral knee extensor fatigue on force and balance of the contralateral limb.
abstract: OBJECTIVE
  Fatigue in one limb can decrease force production in the homologous muscle as well as other muscles of the non-fatigued limb affecting balance. The objective of the study was to examine the effect of unilateral knee extensor fatigue on the non-fatigued limb's standing balance, muscle force and activation.
  
  
  METHODS
  Sixteen healthy male subjects performed pre-fatigue balance trials, warm-up exercises, maximum voluntary isometric contractions, a knee extensors fatigue protocol, and post-fatigue balance trials. The fatigue protocol consisted of sets of 15 consecutive isometric contractions of 16 s each with 4 s recovery between repetitions, which were performed at 30% peak force for the dominant knee extensor muscles. Additional sets of contractions continued until a 50% decrease in MVIC knee extensor force was observed. Pre- and post-fatigue balance assessment consisted of transition from double to single leg standing and also single leg standing trials, which were performed bilaterally and in randomized order.
  
  
  RESULTS
  The peak force and F100 were significantly decreased by 44.8% (ES = 2.54) and 39.9% (ES = 0.59), respectively, for the fatigued limb post-fatigue. There were no significant changes in the non-fatigued limb's muscle force, activation, muscle onset timing or postural stability parameters.
  
  
  CONCLUSIONS
  While the lack of change in non-fatigued limb force production is in agreement with some of the previous literature in this area, the lack of effect on postural measures directly contradicts earlier work. It is hypothesized that discrepancies in the duration and the intensity of the fatigue protocol may have accounted for this discrepancy.
authors.affiliation: School of Human Kinetics and Recreation, Memorial University of Newfoundland, St. John's, NL, A1C 5S7, Canada.
authors.forename: Shruti
authors.initials: S
authors.lastname: Arora
authors.affiliation: School of Human Kinetics and Recreation, Memorial University of Newfoundland, St. John's, NL, A1C 5S7, Canada.
authors.forename: Shawn
authors.initials: S
authors.lastname: Budden
authors.affiliation: School of Human Kinetics and Recreation, Memorial University of Newfoundland, St. John's, NL, A1C 5S7, Canada.
authors.forename: Jeannette M
authors.initials: JM
authors.lastname: Byrne
authors.affiliation: School of Human Kinetics and Recreation, Memorial University of Newfoundland, St. John's, NL, A1C 5S7, Canada. dbehm@mun.ca.
authors.forename: David G
authors.initials: DG
authors.lastname: Behm
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D006801:Humans; D007537:Isometric Contraction; D007717:Knee / Q000502:physiology*; D008297:Male; D018763:Muscle Fatigue; D018482:Muscle, Skeletal / Q000502:physiology*; D004856:Postural Balance
keywords: Crossover fatigue; Electromyography; Equilibrium; Isometric; Stability; Strength