title: Alternative countermovement-jump analysis to quantify acute neuromuscular fatigue.
abstract: OBJECTIVE
  To examine the reliability and magnitude of change after fatiguing exercise in the countermovement-jump (CMJ) test and determine its suitability for the assessment of fatigue-induced changes in neuromuscular (NM) function. A secondary aim was to examine the usefulness of a set of alternative CMJ variables (CMJ-ALT) related to CMJ mechanics.
  
  
  METHODS
  Eleven male college-level team-sport athletes performed 6 CMJ trials on 6 occasions. A total of 22 variables, 16 typical (CMJ-TYP) and 6 CMJ-ALT, were examined. CMJ reproducibility (coefficient of variation; CV) was examined on participants' first 3 visits. The next 3 visits (at 0, 24, and 72 h postexercise) followed a fatiguing high-intensity intermittent-exercise running protocol. Meaningful differences in CMJ performance were examined through effect sizes (ES) and comparisons to interday CV.
  
  
  RESULTS
  Most CMJ variables exhibited intraday (n = 20) and interday (n = 21) CVs of <10%. ESs ranging from trivial to moderate were observed in 18 variables at 0 h (immediately postfatigue). Mean power, peak velocity, flight time, force at zero velocity, and area under the force-velocity trace showed changes greater than the CV in most individuals. At 24 h, most variables displayed trends toward a return to baseline. At 72 h, small increases were observed in time-related CMJ variables, with mean changes also greater than the CV.
  
  
  CONCLUSIONS
  The CMJ test appears a suitable athlete-monitoring method for NM-fatigue detection. However, the current approach (ie, CMJ-TYP) may overlook a number of key fatigue-related changes, and so practitioners are advised to also adopt variables that reflect the NM strategy used.
authors.affiliation: School of Exercise Science, Physical and Health Education, University of Victoria, Victoria, BC, Canada.
authors.forename: Rob
authors.initials: R
authors.lastname: Gathercole
authors.forename: Ben
authors.initials: B
authors.lastname: Sporer
authors.forename: Trent
authors.initials: T
authors.lastname: Stellingwerff
authors.forename: Gord
authors.initials: G
authors.lastname: Sleivert
mesh_terms: D000328:Adult; D001696:Biomechanical Phenomena; D005080:Exercise Test / Q000379:methods*; D006801:Humans; D008297:Male; D018763:Muscle Fatigue / Q000502:physiology*; D009469:Neuromuscular Junction / Q000502:physiology*; D059385:Plyometric Exercise; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013177:Sports / Q000502:physiology*; D055815:Young Adult