Will the age of peak ultra-marathon performance increase with increasing race duration?

Background Recent studies found that the athlete's age of the best ultra-marathon performance was higher than the athlete's age of the best marathon performance and it seemed that the athlete's age of peak ultra-marathon performance increased in distance-limited races with rising distance.Methods We investigated the athlete's age of peak ultra-marathon performance in the fastest finishers in time-limited ultra-marathons from 6 hrs to 10 d. Running performance and athlete's age of the fastest women and men competing in 6 hrs, 12 hrs, 24 hrs, 48 hrs, 72 hrs, 144 hrs (6 d) and 240 hrs (10 d) were analysed for races held between 1975 and 2012 using analysis of variance and multi-level regression analysis.Results The athlete's ages of the ten fastest women ever in 6 hrs, 12 hrs, 24 hrs, 48 hrs, 72 hrs, 6 d and 10 d were 41 ± 9, 41 ± 6, 42 ± 5, 46 ± 5, 44 ± 6, 42 ± 4, and 37 ± 4 yrs, respectively. The athlete's age of the ten fastest women was different between 48 hrs and 10 d. For men, the athlete's ages were 35 ± 6, 37 ± 9, 39 ± 8, 44 ± 7, 48 ± 3, 48 ± 8 and 48 ± 6 yrs, respectively. The athlete's age of the ten fastest men in 6 hrs and 12 hrs was lower than the athlete's age of the ten fastest men in 72 hrs, 6 d and 10 d, respectively.Conclusion The athlete's age of peak ultra-marathon performance did not increase with rising race duration in the best ultra-marathoners. For the fastest women ever in time-limited races, the athlete's age was lowest in 10 d (~37 yrs) and highest in 48 hrs (~46 yrs). For men, the athlete's age of the fastest ever in 6 hrs (~35 yrs) and 12 hrs (~37 yrs) was lower than the athlete's age of the ten fastest in 72 hrs (~48 yrs), 6 d (~48 yrs) and 10 d (~48 yrs). The differences in the athlete's age of peak performance between female and male ultra-marathoners for the different race durations need further investigations.