title: Impact of weather on marathon-running performance.
abstract: Marathon running performance slows in warm weather conditions, but the quantitative impact of weather has not been established.
  
  
  OBJECTIVE
  To quantify the impact of weather on marathon performance for different populations of runners.
  
  
  METHODS
  Marathon results and weather data were obtained for the Boston, New York, Twin Cities, Grandma's, Richmond, Hartford, and Vancouver Marathons for 36, 29, 24, 23, 6, 12, and 10 yr, respectively. The race results were broken into quartiles based on the wet-bulb globe temperature (Q1 5.1-10 degrees C, Q2 10.1-15 degrees C, Q3 15.1-20 degrees C, and Q4 20.1-25 degrees C). Analysis of the top three male and female finishers as well as the 25th-, 50th-, 100th-, and 300th-place finishers were compared with the course record and then contrasted with weather.
  
  
  RESULTS
  Marathon performances of top males were slower than the course record by 1.7 +/- 1.5, 2.5 +/- 2.1, 3.3 +/- 2.0, and 4.5 +/- 2.3% (mean +/- SD) for Q1-Q4, respectively. Differences between Q4 and Q1, Q2, and between Q3, and Q1 were statistically different (P < 0.05). The top women followed a similar trend (Q1 3.2 +/- 4.9, Q2 3.2 +/- 2.9, Q3 3.8 +/- 3.2, and Q4 5.4 +/- 4.1% (mean +/- SD)), but the differences among quartiles were not statistically significant. The 25th-, 50th-, 100th-, and 300th-place finishers slowed more than faster runners as WBGT increased. For all runners, equivalence testing around a 1% indifference threshold suggests potentially important changes among quartiles independently of statistical significance.
  
  
  CONCLUSIONS
  There is a progressive slowing of marathon performance as the WBGT increases from 5 to 25 degrees C. This seems true for men and women of wide ranging abilities, but performance is more negatively affected for slower populations of runners.
authors.affiliation: U.S. Army Research Institute of Environmental Medicine, Natick, MA 01760, USA. Matthew.Ely@na.amedd.army.mil
authors.forename: Matthew R
authors.initials: MR
authors.lastname: Ely
authors.forename: Samuel N
authors.initials: SN
authors.lastname: Cheuvront
authors.forename: William O
authors.initials: WO
authors.lastname: Roberts
authors.forename: Scott J
authors.initials: SJ
authors.lastname: Montain
mesh_terms: D000328:Adult; D003080:Cold Temperature; D005260:Female; D006358:Hot Temperature; D006801:Humans; D008297:Male; D010807:Physical Endurance / Q000502:physiology*; D010809:Physical Fitness / Q000502:physiology*; D011446:Prospective Studies; D012420:Running / Q000502:physiology*; D012737:Sex Factors; D013696:Temperature; D013997:Time Factors; D014887:Weather