Table 2. Coefficients and function fit for the asymptotic limit prediction. Event Eastward Crew transatlantic Westward Solo transatlantic Streif down-hill Speed ski record Hour cyling record IHPVA Oxford–Cambridge Vasaloppet Elfstedentocht Ironmann Hawaı¨ Channel crossing Hour cyling record ICU Date for asymptote achievement b 2084 2107 2058 2043 2086 2020 2022 2045 2003 2051 2026 CI 2050–2134 2050–2206 2045–2072 2021–2077 2057–2126 1990–2107 1994–2096 2027–2065 2000–2006 2017–2109 1984–2134 84.7 155.8 108.7 1.39 91.94 973.1 12998 6.45 482.2 399.4 49.80 CI 70.2–98.7 66–246 106–110 1.36–1.43 88.3–95.5 957–989 6.40–6.50 480–483 325–460 49.4–51.2 12650–13357 Sport Performance Evolution b 34.53 23.89 49.89 41.07 38.45 45.05 47.84 46.33 68.31 42.76 70.89 b9 84.77 77.71 97.56 97.73 94.35 99.40 98.95 99.03 99.64 91.41 99.79 Year calculated for achieving 99.95% of the asymptote with confidence interval (CI); b is the asymptotic limit; b is the progression range from the beginning of the event expressed as a percentage of the predicted asymptotic limit; b9 is the level of the actual BP expressed as a percentage of the asymptotic limit. Asymptotic limits b expressed in seconds for Oxford–Cambridge, Vasaloppet, Streif and speed ski record (for 100 meters); in minutes for the Hawaii Ironman and channel crossing; in hours for the Eastward, Westward transatlantic records and Elfstedentocht; in kilometres for the hour cycling records. doi:10.1371/journal.pone.0003653.t002 boats, which largely increased boat speed in order to limit technology influence and too expensive materials [4]. Anti-doping policies are elaborated to restrain pharmacological impacts within health perspectives [25] but technological advances are accepted within sport rules and identity (e.g. minimum weights for each class boat in rowing; Vasaloppet performed in classic style; Channel crossing with swim suits and hat without thermal protection or buoyancy capabilities) [4,7,15]. Conversely, the speed ski record, one of the fastest non motorized sport on land, seems to have reached its limits after 70 years of technological improvements under major environmental constraints (e.g. air penetration coefficient, snow quality, slope). Thus, if international federations, pushed by public demand and media coverage, want to develop sport on a pure performance basis with the fascination of newly established records, their need for technology will constantly increase. Swimming is the recent demonstration of such evolution with the introduction of swimming suits in 1998 and of second generation models in 2008 that allow for a 1 to 2% increase in speed [26]. However, close future and popularity of these sport monuments depend more on their history, identity and scenery than on continuous performance increase. The present study suggests: i) the universality of the piecewise exponential model to describe the evolution of very short (1,4s) to very long sport performances (400 hours), six orders of magnitude References 1. Berthelot G, Thibault V, Tafflet M, Escolano S, El Helou N, et al. (2008) The citius end: world records progression announces the completion of a brief ultra- physiological quest. PloS One 3: e1552. 2. Nevill AM, Whyte GP (2005) Are there limits to running World Records? Med Sci Sports Exerc 37: 1785–1788. 3. Smith DJ (2003) A framework for understanding the training process leading to elite performance. Sports Med 33: 1103–1126. 4. The international rowing federation website. Available: http://www.worldrow- ing.com. 5. The Oxford Cambridge Boat Race website. Available: http://www.theboatrace. org. 6. Wikipedia free encyclopedia website. Available: http://en.wikipedia.org. 7. The Vasaloppet website. Available: http://www.vasaloppet.se. 8. Elfstedentocht website. 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