title: Variability of competitive performance of distance runners.
abstract: OBJECTIVE
  The typical variation in an athlete's performance from race to race sets a benchmark for assessing the utility of performance tests and the magnitude of factors affecting medal prospects. We report here the typical variation in competitive performance of endurance runners.
  
  
  METHODS
  Repeated-measures analysis of log-transformed official race times provided the typical within-athlete variation in performance as coefficients of variation (CV). The types of race were cross-country runs (4 races over 9 wk), summer road runs (5 races over 4 wk), winter road runs (4 races over 9 wk), half marathons (3 races over 13 wk and 2 races over 22 wk), and marathons (2 races over 22 wk).
  
  
  RESULTS
  Typical variation of times for the fastest quartile of male runners was 1.2-1.9% in the cross-country and road runs, 2.7% and 4.2% in half marathons, and 2.6% in marathons. Times for the slower half of runners in most events were more variable than those of the faster half (ratio of slower/faster CV, 1.0-2.3). Times of younger adult runners were more variable than times of older runners (ratio of younger/older CV, 1.1-1.8). Times of male runners were generally more variable than those of female runners (ratio of male/female CV, 0.9-1.7).
  
  
  CONCLUSIONS
  Tests of endurance power suitable for assessing the smallest worthwhile changes in running performance for top runners need CV < or = 2.5% and < or = 1.5% for tests simulating half or full marathons and shorter running races, respectively. Most of the differences in variability of race times between types of race, ability groups, age groups, and sexes probably arise from differences in competitive experience and attitude toward competing.
authors.affiliation: Department of Physiology and School of Physical Education, University of Otago, Dunedin, New Zealand. will.hopkins@otago.ac.nz
authors.forename: W G
authors.initials: WG
authors.lastname: Hopkins
authors.forename: D J
authors.initials: DJ
authors.lastname: Hewson
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D001290:Attitude; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010807:Physical Endurance / Q000502:physiology*; D011237:Predictive Value of Tests; D012420:Running / Q000502:physiology*; D012737:Sex Factors; D013177:Sports; D013647:Task Performance and Analysis