World records in many athletic events are peaking - and will not be broken unless athletes take drugs, say researchers.
The study, "Are there limits to running world records?", suggests faster times may prove elusive.
The current women's 1500m record may never be broken, said Professor Alan Nevill, without fundamental changes to the genetic structure of human beings.
Prof Nevill says many running records are "already nearing their limits".
The paper, co-written by Professor Nevill at the University of Wolverhampton and Professor Greg Whyte from the English Institute of Sports, challenges previous scientific research that there was no limit to human performance and that women would eventually run as fast as men.
Professors Nevill and Whyte re-interpreted data of previous performances and concluded that records set to
plateau .
"For the first time we have identified that there could be a limit to performance and that world records will not continue to rise," said Professor Nevill of the University of Wolverhampton.
"Many of the established men and women's middle and long distance running records are already nearing their limits.
"The results, of course, assume that athletes in the future do not benefit from scientific engineering or drug use."
Professor Nevill told the BBC he did not envisage the current women's record for the 1500m - held by Qu Yunxia of China - ever being broken.
This was one of the races won by Kelly Holmes at last year's Athens Olympics in a time of 3:57.90, well below Qu Yunxia's 3:50.46 set in Beijing in 1993.
But Professor Nevill stressed that the public would never lose interest in athletics, even if new records were no longer set.

(Agencies)许多体育项目的世界记录已经达到了顶峰，并且不会再被打破，除非运动运服用违禁药物，研究人员说。
一篇题为《赛跑世界记录是否有极限》的论文指出，跑得更快似乎不太可能。
阿兰·内维尔教授说，如果不改变人类的基因结构，目前女子1500米跑的世界记录也许很难被打破。
内维尔教授说许多赛跑世界记录“已逼近极限”。
英国胡弗汉普顿大学的内维尔教授和英国体育学院的葛雷格·怀特教授合作撰写了这篇论文，对之前的某些科学研究提出异议，那些研究认为人类的能力没有极限，而且女性终将跑得和男性一样快。
内维尔和怀特教授重新解释了以前的比赛成绩数据，并得出这样的结论：世界记录开始趋于稳定。
“我们第一次认识到人类的能力是有极限的，世界记录不会一直向上攀升，”胡弗汉普顿大学的内维尔教授说。
“现有的许多男子和女子中长跑世界记录已经接近极限了。”
“当然，这一结论的前提是将来运动员不会通过科学指导或服用药物来提高成绩。”
内维尔教授告诉英国国际广播公司说他无法设想目前由中国选手曲云霞保持的女子1500米世界记录有一天会被打破。
在去年的雅典奥运会上，英国选手凯莉o霍尔姆斯以3分57秒90的成绩获得了该项目的金牌，但这一成绩远远落后于曲云霞1993年在北京创造的3分50秒46的世界记录。
但是，内维尔教授强调说，即使没有新的世界记录诞生，人们也绝不会对田径运动失去兴趣。