title: Variability of competitive performance of elite athletes: a systematic review.
abstract: BACKGROUND
  Estimates of the variability that athletes show from competition to competition provide information about the relative contributions of environmental and other factors affecting competitive performance. Smallest and other important thresholds for assessing changes in performance in competitions and field or laboratory tests can also be derived from estimates of variability.
  
  
  OBJECTIVE
  To systematically review estimates of within-athlete variability of competitive performance in various sports.
  
  
  METHODS
  We searched SPORTDiscus and Google Scholar for studies providing estimates of within-athlete variability between competitions. Estimates are reported here as coefficients of variation (CV) only for the best athletes. Some studies also combined within-athlete variability with between-athlete differences into a measure of predictability expressed as an intraclass correlation coefficient, reported here for the full field of competition.
  
  
  RESULTS
  Skeleton and 1,000-m speed-skating times have the lowest within-athlete variability (CV of 0.15% and 0.4%, respectively), apparently because of the effect of the initial phase of the race on race dynamics. Times in sprint and endurance sports also have relatively low variability (0.6-1.4%), reflecting the predominant contribution of mean power output to performance. The power-velocity relationship tends to make CV for time smaller in sports performed against water or wind resistance, but this effect is offset by variability in the effects of wind and water on individual athletes. Sports requiring explosive power in a single effort, such as field events and weightlifting, have larger CVs for their performance measures (1.4-3.3%), likely reflecting substantial contributions of skill. Sports with the greatest within-athlete variability (~50%) were those with subjective scores (e.g. surfing). Predictability correlations ranged from 0.17 (half-pipe snowboarding) to 0.93 (cross-country skiing). There was little difference in variability or predictability between men and women. Application of power-velocity and power-duration relationships allows transformation of the estimates of within-athlete variability of competitive performance into thresholds for smallest and other important changes in performance in laboratory and field tests of power output.
  
  
  CONCLUSIONS
  Understanding the contributions of race dynamics, power output, environment, skill, and subjective scoring to the variability of athletic performance should help identify and evaluate strategies for performance enhancement.
authors.affiliation: High Performance Sport New Zealand, 17 Antares Place, Mairangi Bay, 0632, Auckland, New Zealand, rita.malcata@hpsnz.org.nz.
authors.forename: Rita M
authors.initials: RM
authors.lastname: Malcata
authors.forename: Will G
authors.initials: WG
authors.lastname: Hopkins
mesh_terms: D056352:Athletes; D054874:Athletic Performance / Q000502:physiology*; D003163:Competitive Behavior / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D015203:Reproducibility of Results; D013177:Sports
references.citation: Sports Med. 2001;31(3):211-34
references.pmid: 11286357
references.citation: Med Sci Sports Exerc. 2009 Jan;41(1):3-13
references.pmid: 19092709
references.citation: Int J Sports Physiol Perform. 2014 Jan;9(1):5-11
references.pmid: 23799826
references.citation: J Strength Cond Res. 2004 Aug;18(3):650-3
references.pmid: 15320651
references.citation: Sports Biomech. 2007 May;6(2):224-43
references.pmid: 17892098
references.citation: Med Sci Sports Exerc. 1999 Mar;31(3):472-85
references.pmid: 10188754
references.citation: J Sports Sci. 2009 Feb 15;27(4):367-72
references.pmid: 19235005
references.citation: J Sports Sci. 2004 Apr;22(4):339-45
references.pmid: 15161107
references.citation: Sports Med. 2000 Jul;30(1):1-15
references.pmid: 10907753
references.citation: J Sports Sci. 2004 Jul;22(7):613-20
references.pmid: 15370491
references.citation: Int J Sports Physiol Perform. 2010 Jun;5(2):165-76
references.pmid: 20625189
references.citation: Int J Sports Physiol Perform. 2010 Jun;5(2):210-7
references.pmid: 20625193
references.citation: J Strength Cond Res. 2010 Jan;24(1):135-9
references.pmid: 19644407
references.citation: Med Sci Sports Exerc. 2011 Nov;43(11):2155-60
references.pmid: 21502896
references.citation: Med Sci Sports Exerc. 2005 Apr;37(4):696-701
references.pmid: 15809572
references.citation: J Sports Sci. 2009 Mar;27(5):535-9
references.pmid: 19219736
references.citation: J Strength Cond Res. 2006 Aug;20(3):579-83
references.pmid: 16937971