I don't know much about track and field, but I found this article interesting, excerpt:
Today 64 percent of track and field world records have stood since 1993. One world record, the women’s 1,500 meters, hasn’t been broken since 1980. When Berthelot published his study last year in the online journal PLoS One, he made the simple but bold argument that athletic performance had peaked. On the whole, Berthelot said, the pinnacle of athletic achievement was achieved around 1988. We’ve been watching a virtual stasis ever since.
It seems unlikely to me that we have reached a true peak, rather a temporary plateau with slower-than-average growth, until the next breakthrough in training, technique, genetic manipulation, or whatever. Does that sound familiar?