title: Analysis of swimming performance in FINA World Cup long-distance open water races.
abstract: BACKGROUND
  Age and peak performance in ultra-endurance athletes have been mainly investigated in long-distance runners and triathletes, but not for long-distance swimmers. The present study investigated the age and swimming performance of elite ultra-distance swimmers competing in the 5-, 10- and 25-km Fédération Internationale de Natation (FINA) World Cup swimming events.
  
  
  METHODS
  The associations of age and swimming speed in elite male and female swimmers competing in World Cup events of 5-, 10- and 25-km events from 2000 to 2012 were analysed using single and multi-level regression analyses.
  
  
  RESULTS
  During the studied period, the swimming speed of the annual top ten women decreased significantly from 4.94 ± 0.20 to 4.77 ± 0.09 km/h in 5 km and from 4.60 ± 0.04 to 4.44 ± 0.08 km/h in 25 km, while it significantly increased from 4.57 ± 0.01 to 5.75 ± 0.01 km/h in 10 km. For the annual top ten men, peak swimming speed decreased significantly from 5.42 ± 0.04 to 5.39 ± 0.02 km/h in 5 km, while it remained unchanged at 5.03 ± 0.32 km/h in 10 km and at 4.94 ± 0.35 km/h in 25 km. The age of peak swimming speed for the annual top ten women remained stable at 22.5 ± 1.2 years in 5 km, at 23.4 ± 0.9 years in 10 km and at 23.8 ± 0.9 years in 25 km. For the annual top ten men, the age of peak swimming speed increased from 23.7 ± 2.8 to 28.0 ± 5.1 years in 10 km but remained stable at 24.8 ± 1.0 years in 5 km and at 27.2 ± 1.1 years in 25 km.
  
  
  CONCLUSIONS
  Female long-distance swimmers competing in FINA World Cup races between 2000 and 2012 improved in 10 km but impaired in 5 and 25 km, whereas men only impaired in 5 km. The age of peak performance was younger in women (approximately 23 years) compared to men (about 25-27 years).
authors.forename: Matthias Alexander
authors.initials: MA
authors.lastname: Zingg
authors.forename: Christoph Alexander
authors.initials: CA
authors.lastname: Rüst
authors.forename: Thomas
authors.initials: T
authors.lastname: Rosemann
authors.forename: Romuald
authors.initials: R
authors.lastname: Lepers
authors.affiliation: Facharzt FMH für Allgemeinmedizin, Gesundheitszentrum St, Gallen, Vadianstrasse 26, St, Gallen, 9001 Switzerland. beat.knechtle@hispeed.ch.
authors.forename: Beat
authors.initials: B
authors.lastname: Knechtle